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2020 GeoPRISMS NSF Awards All GeoPRISMS NSF Awards are available on the GeoPRISMS website A series of NSF-funded cross-disciplinary workshops will take place in 2021 and 2022 to help achieve GeoPRISMS synthesis and integration, and identify future opportunities while keeping the community engaged beyond the GeoPRISMS Program. These workshops will focus on cross-cutting themes identified by the GeoPRISMS Community at the 2019 Theoretical and Experimental Institute and workshops at the 2019 AGU Fall Meeting. For more information about the workshops, please contact the Principal Investigators. NSF Award 2025668 Plate boundary structure and deformation workshop Helen Janiszewski ([email protected]) NSF Award 2025625 GeoPRISMS synthesis workshop: Volatiles from source to surface Madison Myers ([email protected]) NSF Award 2025606 Cascade21: A workshop to catalyze and synthesize understanding of the role of magmatism in an archetype continental arc Adam Kent ([email protected]) NSF Award 2025105 GeoPRISMS synthesis workshop: The geological fingerprints of slow earthquakes David Schmidt ([email protected]) NSF Award 2025254 Synthesizing emerging results and identifying future research in an early-stage, magma-poor rift: A workshop in the southern East Africa Rift System Donna Shillington ([email protected]), James Gaherty NSF Award 2025577 GeoPRISMS synthesis workshop: Extensional processes across tectonic settings and time scales Dennis Harry ([email protected]) NSF Award 2025195 Cooperative Institute for Dynamic Earth Research: Fluid and magma transport at plate boundaries Bruce Buffett ([email protected]), Barbara Romanowicz, Michael Manga 51Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Photo by S. Penniston-DorlandScience Reviews Photo by H. MarschallUnraveling subduction zone processes: Photo by I. BoianjuEvidence from exhumed rocks Photo by C. RoweSarah Penniston-Dorland (University of Maryland ) and Christie Rowe (McGill University) Introduction Subduction zones are a major source of seismic and volcanic hazard, the site of recycling of crustal material and volatiles, and the creation of new crust that ultimately forms continents. Exhumed rocks, returned to the surface of the earth by uplift and erosion, offer the only opportunity for direct observations of the architecture, deformation mechanisms, mineralogy, and chemistry of the subduction plate interface at depths greater than drilling can reach (Moore et al., 2007). To date, ocean drilling has sampled shallow décollements and splay faults in both creeping margins (Saffer et al., 2018) and the rupture zones of great earthquakes about 1-3 km below the ocean floor (Chester et al., 2013; Tobin et al., 2019). The constraints of sample size and lack of local structural context in drill cores can be restricting, and the technological limits of drilling make it impossible to sample the depths where locking, healing and creeping behaviors are controlled or where metamorphic reactions and fluid-mineral elemental exchanges start to significantly modify the composition and structure of rocks. These rocks display the incredible complexity, diversity and richness of mechanical and chemical processes at work in subduction thrust systems and represent the key resource for understanding locking and earthquake cycles, fluid cycling, episodic tremor and slip, flux of elements from slabs to forearcs and to arc magma systems, and other processes of interest at depths greater than the limits of drilling. 52 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

From 2000-2012, MARGINS supported several field-based studies seismic, geodetic, and geochemical studies of sediments, rocks and of exhumed subduction rocks. More recently (2010-present), fluids from trenches, forearcs and arc volcanoes). Looking ahead, GeoPRISMS has been supportive of the community of scientists we also identify some areas of opportunity for future research. It will studying exhumed rocks through research grants, support of be important to determine how we can better integrate data from workshops focused on exhumed rocks, and web support for rocks exhumed from fossil subduction systems with observations of initiatives like the ExTerra Field Institute and Research Endeavor modern subduction zones to better understand the processes that project (E-FIRE). E-FIRE has involved a group of students, post- generate dangerous volcanic eruptions and megathrust earthquakes. docs and faculty from nine different U.S. institutions investigating exhumed rocks through Field Institutes in the Western Alps in Metamorphic conditions and timing of processes active collaboration with European scientists. The samples collected at the plate interface through E-FIRE are integrated into a shared collection that will also be made available to the public upon request. Since only a few of Linking exhumed rocks to particular depths, temperature conditions, these types of studies have been explicitly funded by MARGINS/ or slip behaviors in active subduction zones forms the basis for GeoPRISMS grants, this contribution covers a broader range of applying insights from studies of exhumed rocks back to modern studies and describes recent insights from research investigating settings. Exhumed rocks were a key component in the understanding subduction-related rocks. of subduction zones and the new paradigm of plate tectonics in the A common goal in studies of exhumed subduction-related rocks late 1960s-early 1970s. The mineral assemblages of blueschist and is connecting the record of processes in the rocks to the record eclogite were found to be consistent with relatively cold temperatures of processes occurring in active subduction zones. Sibson (1989) for a given pressure (high pressure/temperature, written as high and Moore et al. (2007) laid out the argument for comparing P/T) and this fact, along with their field relationships, led to the studying exhumed rocks to geophysical observations of active recognition that these were rocks exhumed from fossil subduction margins to understand controls on locking and rupture within zones (Ernst 1970, 1971).The identification of paired metamorphic the seismogenic zone (approx. 150-350°C: Hyndman et al., 1997). belts in which exhumed rocks containing these high P/T assemblages Connections between geologic observations and active systems can were found in regional-scale belts parallel to rocks containing low be made, for example, through seismology and geophysical surveys P/T assemblages led to the understanding of a relatively cold plate (Abers, 2005; Moore et al., 2007), magnetotelluric and geodetic subducting underneath a relatively hot volcanic arc (Miyashiro, observations, and the chemistry of arc volcanic rocks (Bebout, 2007; 1973). These studies and many others confirmed that the conditions Marschall and Schumacher, 2012). Interpreting the metamorphic within a subduction zone were relatively cold, but just how cold is mineral assemblages, deformation fabrics, and structural and still an outstanding question. This issue is critical as it is central to chemical tracers of fluids in exhumed rocks therefore requires a understanding the thermal structure of the plate interface, which broad understanding of how and why these features form under controls the rheological behavior of materials, release of volatiles, high-pressure/low-temperature and variable stress states in active and the cycling of elements during subduction metamorphism. subduction zones. Estimates of the thermal structure of the plate interface comes from Contextualizing field exposures, particularly those for deeper rocks, prograde paths and peak P-T conditions of exhumed metamorphic in terms of modern plate boundaries can present a significant rocks record temperatures that are on average 200-300°C hotter than challenge. One important caveat is that only a fraction of subducted geodynamic models of the thermal structure of modern subduction rocks is returned to the surface with the record of subduction- zones (see Fig. 1 for comparison, Penniston-Dorland et al., 2015; related structures and metamorphism intact and this sampling may van Keken et al., 2011, 2018). This discrepancy is an active area of be non-random, creating a biased sample (van Keken et al., 2018). debate and ongoing research. Geophysical observations of active subduction zones typically Classically, evaluation of P-T conditions has relied on equilibrium reveal variations on the km-scale or greater while observations of thermodynamics.This methodology relies on the underlying exhumed rocks can be made at much smaller scales, down to the assumption of equilibrium among minerals in rocks, which can be submicron-scale. Observations of processes at active subduction problematic due to reaction kinetics. Care must also be taken in this margins are limited to the temporal scale of human observations type of analysis to avoid overprints acquired on the exhumation path. (hundreds of years) while geochronological methods permit Recent advances in methods have allowed researchers to overcome accessing timescales on the order of millions of years of subduction some of these barriers. Advances in bulk-rock thermodynamic history. Understanding sample context and being able to properly modeling include using thin section scale X-ray maps to properly correlate processes observed in the rock record with processes in determine the effective bulk composition of a rock (Lanari et al., active subduction systems is especially important. 2014; Lanari and Engi, 2017). Methods for fractionating garnet In this contribution, we describe recent themes of research on from the bulk rock chemistry (Dragovic et al., 2012) allow for exhumed subduction-related rocks that relate to the goals of greater accuracy in modeling. Recent developments in trace- GeoPRISMS and MARGINS, highlighting studies that make element thermometry (such as that based on Zr-in-rutile,Tomkins connections to our observations from active subduction zones (e.g. et al., 2007) require analysis of only a single phase, removing some of the concerns about equilibrium among multiple phases. Elastic thermobarometry using Raman spectroscopy (e.g., quartz in garnet; 53Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Angel et al., 2017a, b), relying on the elastic properties of minerals, estimate. Past workers have used compaction-depth curves derived allow petrologists to explore P-T conditions recorded by rocks from oil industry empirical data (Moore and Allwardt, 1980) and unhindered by assumptions of equilibrium. fluid inclusion barometry, although this records fluid pressure rather At shallow depths within subduction systems where temperatures than lithostatic stress (Vrolijk, 1987). Pressure and/or temperature are lower than ~300-350°C, mineral growth is sluggish and not at estimates can be gained from the appearance of indicator minerals equilibrium. Subduction-related metamorphism can be difficult (e.g., lawsonite or jadeite in greywackes of the Franciscan Complex; to distinguish from seafloor metasomatism and/or ridge-crest Maruyama et al., 1985). metamorphism of oceanic crust. Peak temperatures can be estimated using fluid inclusion thermometry (Vrolijk et al., 1988, Hashimoto Fluids and geochemical cycling et al. 2014), clay maturity (Kawamura et al., 2011; Fukuchi et al., 2014), thermal maturity of organic molecules (Savage et al., 2014), Subduction zones are sites of extensive chemical and physical opal diagenesis (Spinelli et al., 2006), and vitrinite reflectance exchange between Earth’s surface and the mantle. Fluid release from (Underwood, 1989, Sakaguchi et al., 2011). Pressure, often used as subducting slabs may influence seismicity and is associated with the a proxy for depth, is more difficult than temperature to precisely generation of the magmas that feed arc volcanic eruptions. Mass transfer associated with subduction includes cycling of volatiles Figure 1. Comparison of P-T estimates from such as H2O and CO2 between Earth’s surface and deep mantle exhumed rocks and P-T estimates from (see this issue Fischer et al. p. 40). This cycling affects the CO2 geodynamic models. Geothermal gradients of content of Earth’s atmosphere and directly impacts Earth’s climate 5° C to 20° C/km are indicated with thin black and affects Earth’s habitability (Stewart et al., 2019). These volatile lines. Thick light gray lines show boundaries for elements also affect the rheological behavior of deep materials both blueschist (lower) and eclogite (upper) facies within the subduction system and deeper in the mantle. Studies of metamorphism. Colored diamonds are peak P-T exhumed rocks contribute to our understanding of both geochemical estimates from exhumed rocks, different colors cycling (what is returned to the surface and what continues into the correspond to geographic location of data and red mantle) and chemistry of subduction-related fluids and the nature line and shaded red field represent the average of fluid flow. Fluid release by prograde mineral reactions has also and 2 standard deviation spread of those estimates been invoked to explain many plate boundary-scale phenomena, (see Penniston-Dorland et al., 2015). Thick blue line including the existence of double Wadati-Benioff zones (Iyer et al., and shaded blue field are median and spread of 2012), and the strengthening of the slab pull force due to density P-T paths from geodynamic models and P-T paths increase with eclogitization (e.g. Spence, 1987). for Tohoku and Cascadia are shown as thin blue lines (van Keken et al., 2011). Fluid release during subduction occurs first at shallow depths due to compaction and mechanical expulsion of fluids in the first ~3-7 km Exhumed rock record & model predictions of burial (Jarrard, 2003, Saffer and Tobin, 2011). Pore fluid release by compaction may be channelized with deeper-sourced fluids along 4.0 the plate boundary fault and forearc structures, modulating pore pressure conditions in those faults which affect seismic activity and PD15 2σ forearc temperature structure (Kastner et al. 2014). Breakdown of PD15 mean clays and biogenic opal, along with hydrocarbon maturation, liberate significant volumes of fluid and dissolved minerals (Saffer and vK11 all Tobin, 2011). Sheeted vein sets of zeolites and calcite at temperatures ~60-100° C, transitioning to calcite-quartz above 125-150° C, have 3.0 vK11 median been interpreted to record advection of connate and metamorphic Pressure (GPa) 10 °C/km fluids from deeper in the subducting plate (Fig 2a; Meneghini and Moore, 2007; Yamaguchi et al., 2012). Advecting fluids contribute Tohoku to solution creep which forms anisotropic foliations and contributes to fault healing through cementation and veining (Rowe et al., 2011; 5 °C/km Fagereng and den Hartog, 2017). Cascadia Further release at greater depths occurs due to prograde dehydration 2.0 20 °C/km and decarbonation reactions (Hacker 2008). Some elements which Eclogite are mobile at P-T conditions of subduction metamorphism have been defined as tracers of contributions from subducting slabs in lavas 1.0 Blueschist erupting from modern volcanic arcs (Elliott, 2003) (see summaries in Bebout, 2007; 2014; Bebout and Penniston-Dorland, 2016). 0.0 200 400 600 800 0 Temperature (°C) 54 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

A BC 1.5 cm D 5cm E Mélange Garnet amphibolite matrice Reaction rind Figure 2. Images of subduction-related exhumed rocks illustrating features of fluid-rock interaction. A) Tensile veins formed by diagenetic fluid release and fracture of deforming sediments, Sitkinak Formation, AK (Moore and Allwardt, 1980). B) Layered schist with unaltered rock on the left and rock altered by infiltrating fluid which dissolved calcite on the right, Syros, Greece (Ague and Nicolescu, 2014). C) Vein in blueschist rock with eclogite reaction selvage formed due to interaction with externally-derived fluid over timescales of months, Pouébo eclogite mélange, New Caledonia (Taetz et al., 2018). D) Reaction rind surrounding garnet amphibolite block formed in part due to reaction with fluid infiltrating through mélange matrix, Catalina Schist, CA (Penniston- Dorland et al., 2014); e) Mafic block surrounded by finer-grained mélange matrix metasomatized by infiltrating fluids, Catalina Schist, CA (Bebout and Barton, 2002). Photo credit: A) C. Rowe, B) J.J. Ague, C) T. John, D) A.J. Kaufman, E) S. Penniston-Dorland. Enrichments in these slab tracers, including large ion lithophile sediments, in altered basaltic ocean crust and possibly also as a elements such as Ba, Rb, Cs and K in addition to U, Th and Pb constituent of oceanic mantle altered by serpentinization along faults found in arc volcanic rocks are reflected in enrichments of these in the outer rise of subduction trenches (Dasgupta and Hirschmann, same elements observed in exhumed metamorphic rocks (e.g., 2010; Kelemen and Manning, 2015). There is considerable debate Bebout, 2007; 2014) in features such as veins, reaction rinds (Figs. about the amount of subducted carbon that is released due to 2C, 2D) and mélange zones (Fig. 2E) that are associated with metamorphic degassing and returned to Earth’s surface and the fluid-rock interaction. These features are a record of channelized amount stored in the mantle (Piccoli et al. 2016; Scambelluri et al., fluid flow released during prograde devolatilization reactions. The 2016; Stewart et al., 2019; Menzel et al., 2020). Recent work has shed geochemistry of mélange zones reflects mass transport by fluids but light on two major mechanisms of carbon release during subduction: also chemical changes due to mechanical mixing processes that lead decarbonation reactions involving silicates, and congruent carbonate to an unusual hybridized rock chemistry that is in many ways similar dissolution (Fig. 2B; Frezzotti et al., 2011; Ague and Nicolescu, to that of arc volcanic rocks (Marschall and Schumacher, 2012; 2014). The latter mechanism may be more efficient at releasing a Nielsen and Marschall, 2017). The relative role of devolatilization greater proportion of subducted carbonate compared to the former reactions, partial melting at depth, or diapiric rise of hybridized - a clearer picture of the fluxes of carbon produced by these two rocks followed by shallower partial melting in driving the transfer mechanisms in subduction systems is needed in order to constrain of the slab ‘signature’ to arc magmas is an area of ongoing research. the amount of carbon returned to Earth’s surface. While the cycling of H2O in subduction zones has received Arc volcano magmas are oxidized relative to other mantle- considerable attention, recent efforts have turned towards derived magmas (Kelley and Cottrell, 2009). This oxidation has constraining the cycling of other volatile elements, including carbon been postulated to be produced due to the release of oxidized (see this issue Fischer et al. p. 40 for further discussion). Carbon is fluids from the subducting slab. Release of oxidized fluids during transported into the mantle during subduction bound in oceanic prograde metamorphism would result in a decrease in fO2 of the 55Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

subducting slab over time. There is evidence for such a decrease In addition, recent work (Plümper et al., 2017) provides evidence that in fO2 in metamorphic rocks during prograde subduction (e.g., small, micron-scale channelization of fluid produced by dehydration Gerrits et al., 2019), consistent with such fluids contributing to the reactions developed in metamorphosed serpentinites because of elevated oxidation state of the subarc mantle and ultimately to the chemical heterogeneities in the rocks. These heterogeneities resulted oxidation of subduction zone magmas. Some candidates for these in differential development of reaction porosity, which acts to focus oxidizing species include sulfate and carbonate. Components such fluids as they are released. This small-scale process is thought to lead as sulfur are likely to be lost during prograde subduction (Evans to larger-scale channelization of fluid escape through veins that are et al., 2014; Walters et al., 2020), and fluids containing sulfate and observed in many subduction-related terranes without requiring other oxidized species (e.g., carbonate) have the potential to affect fluid overpressure. Advances in geochronology have allowed geochemical cycling of other chemical constituents as well. Evidence geologists to be able to determine timescales of processes that are from metamorphosed serpentinites of the Western Alps suggests longer than those observed in active subduction systems. Dating of that the release of sulfate- or chlorine-rich fluids contributed to the different growth zones in garnets show that prograde fluid release loss of Fe and Zn from the rocks during prograde metamorphism that formed garnets occurred in short pulses associated with heating (Debret et al., 2014; 2016; Pons et al., 2016). Other possibilities for in events that lasted less than 1 Myr (Dragovic et al., 2012; 2015). oxidation of the subarc mantle wedge include reactions involving Other studies focused on fluid flow pathways have used diffusion H+ dissolved in the aqueous fluid (Iacovino et al., 2020) or oxidation speedometry to infer the duration of fluid-rock interactions. These of the mantle wedge due to interaction with ascending melt that is studies have revealed even shorter timescales representing the progressively oxidized due to H2 loss to orthopyroxene during melt duration of fluid flow on the order of days to thousands of years ascent (Tollan and Hermann, 2019). (Fig. 2C; Penniston-Dorland et al., 2010; John et al., 2012; Taetz et al., 2018). These short-duration fluid release events have been linked The mechanisms by which the fluids escape from the relatively to seismic and non-seismic slip phenomena at the plate interface low-permeability high-pressure rocks in which they are generated (Taetz et al., 2018). are not well understood (Ague, 2007; Zack and John, 2007). Seismic velocity models of subduction zones are sensitive to fluid content in Deformation and rheology the subducting slab (Bloch et al., 2018) and along the plate boundary (Audet and Schaeffer, 2018). The locations of episodic tremor and slip Field studies of exhumed faults allow direct observation at the scales are correlated with low P-wave velocity zones interpreted to indicate which control plate boundary strength. Deformation is mainly high fluid content (Shiina et al., 2013; Audet and Schaeffer, 2018), studied at the crystal lattice or grain scale, far below the scale of which correspond with model predictions of the loci of metamorphic resolution for observing processes at active tectonic plate boundaries dehydration (Rondenay et al., 2008; van Keken et al., 2012). Fluid such as interface coupling, earthquake mechanics, transient slip/ production has been associated with tremor and slip observed in creep, fluid flow events, and steady-state creep. Numerical and active subduction zones at depths up to ~50 km, including slow geodetic models yield surface displacement fields associated with slip events and non-volcanic tremor (Fagereng and Diener, 2011; plate boundary deformation, most commonly using rate-and-state Cruz-Atienza et al., 2018). Exhumed rocks provide clues related to friction with elastic plates, and viscoelastic and/or viscous plates and fluid production, including the nature of the release of metamorphic upper asthenosphere (Gerya, 2011, Gao and Wang, 2017). In most fluids, the paths that fluids take once released, and the duration cases, these models prescribe simplified rheological properties to a of fluid flow. Many studies focus on the role of fluid overpressure geometrically abstracted plate boundary architecture. Exhumed rock in brittle fracturing of rocks resulting in fluid flow through these studies can bridge the gap by identifying the scales of importance, the fractures, producing veins (Fig 2a; Compton et al., 2017; Tarling et minerals and the structures responsible for regional deformation and al., 2019; Nishiyama et al., 2020). enabling selection of the most appropriate rheologic models (Moore et al., 2007; Wang et al. 2012, Agard et al., 2018, Bilek and Lay, 2018). Figure 3. Evidence of mixed-mode deformation in exhumed subduction faults. a) Flattening boudinage of sand layer and scaly shale, fabric folded (~125°C, 2-4 km depth, Sitkalidak Island, AK); b) Boudinage of thin sand layers, sharp faults cutting along lower edge of thick sand layer in scaly black shale matrix (~250°C, 12-14 km depth, Pasagshak Point, AK); c) “Snowball” sandstone boudins reveal granular flow as disturbance of bedding-scale sedimentary structures with rounding of rock fragments, Pasagshak Point (Rowe et al., 2011); d) Eclogite with extensional veins boudinaged in garnet blueschist matrix, illustrating competency contrast, Kini Beach, Syros, Greece (Kotowski and Behr 2019); e) Pseudotachylyte cross cuts fragmented sandstone boudins in argillite matrix (Ujiie et al., 2007); f) Crack-seal veins in a record 10s micron-scale increments of slip and opening consistent with low frequency earthquake scaling (~300°C, Crystalls Beach mélange, Fagereng et al. 2010); g) Boudinaged metabasalt and meta chert in metapelite matrix, boudin-normal quartz veins, (~600°C, Damara Belt, Fagereng et al. 2014). Photos a-c) C. Rowe, d) A. Kotowski, e) K. Ujiie, f-g) Å. Fagereng. 56 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

AB C DE G F 57Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Tectonic underplating may preserve subduction plate boundary At higher temperatures (≥300°C), dissolution-precipitation creep is fault surfaces, enabling observation of local structural architecture more efficient (Gratier et al., 1999; Stöckhert et al., 1999) and crystal in field studies of faults from 15 km depth (Kato et al., 2004, plastic deformation becomes prevalent in some minerals, leading Kimura et al., 2012, Rowe et al., 2013, Agard et al., 2016; Regalla to more crystalline textures with interlocking grain boundaries, et al., 2018), but often, especially for deeper examples, reactivation lower permeability rock with deformation fabrics which are more and retrogression during exhumation and the development of consistently aligned with shear and flattening plane orientations exhumation-related structures overprint original geometries and (Figs. 3D-G). The deformation behavior of most minerals in kinematic indicators (Ring and Brandon, 1994, Tembayashi et al., greenschist-blueschist-eclogite metabasites is not well known from 1996, Mihalynuk et al., 2004). Field and microstructural studies experiments, but the appearance of crystallographic preferred of exhumed plate boundary faults reveal the action of multiple orientations demonstrates the prevalence of dislocation creep, deformation mechanisms in complex geometric arrangements, most sometimes in addition to solution creep, predicting bulk viscous (as of which are poorly understood in terms of their rheology, and both opposed to frictional) behavior (Fig. 3; Kim et al., 2012; Kotowski mechanisms and rheology change dramatically with depth in the and Behr, 2019, also see Wheeler, 1992). The combined action of subduction zone. Snapshots of structural complexities in exhumed multiple grain-scale deformation mechanisms contributes to more faults show that changes in material properties during deformation distributed strain, forming increasingly penetrative foliations (Behr affect strain localization, fluid pressure and fluid distribution, and and Platt, 2013; Angiboust et al., 2015; Kotowski and Behr, 2019). trade-offs between deformation mechanisms, which all impact strength and rheology of the plate boundary. Observations of The introduction of serpentinite from the subducting plate through deformation mechanisms, scale and geometry of deforming zones, faulting of the oceanic crust (Polonia et al., 2017) or from mantle and changes in localization with time can directly contribute to hydration of the upper plate, can have dramatic effect on the plate models of subduction plate boundary processes which more closely boundary strength. Serpentinites are frictionally very weak and approximate the relevant characteristics of the natural system. deform viscously at low shear stresses compared to other rock Studies of drill core from accretionary wedges (for the shallowest types at the same conditions (Hirth and Guillot, 2013). The near examples) and exhumed rocks and faults from subduction zones disappearance of earthquake hypocenters in the plate boundary provide insight into the mechanisms and architecture of the plate at depths below the upper plate Moho has been attributed to the boundary zone, and their evolution with depth. Discrete faults probable low shear stress and tendency to creep in serpentinite accommodating localized slip develop very shallowly (Rowe et al., (Hyndman et al., 1997, Peacock and Hyndman, 1999). 2013), synchronous with distributed granular flow in subducting sediments which is prevalent in the uppermost few kilometers (Figs. The spectrum of slip rates in subduction zones has been the focus 3A, C; Fagereng et al., 2019), and may take up a significant component of considerable research during the GeoPRISMS decade (Peng of shear strain while facilitating consolidation, contributing to the and Gomberg, 2010, Araki et al., 2017). Field observations of formation of scaly fabrics in clay-rich sediments (Figs. 3A, B; Karig, exhumed faults have contributed phenomenological models of how 1990, Vannucchi et al., 2003, Vannucchi, 2019). The rheology of deformation at different slip speeds is accommodated, whether on granular deformation is difficult to describe (Chaudhuri et al. 2012), discrete faults or through volumetric strain, and over what scales. but strong feedbacks between shear strength and pore fluid pressure (Xing et al., 2019) are reflected in correlations between deformation Sharp through-going faults experience transient temperature events and pressure transients measured in borehole observatories spikes during earthquakes which are preserved in many forms. (Davis et al. 2011; 2013, Araki et al., 2017). Dissolution-precipitation One spectacular example is pseudotachylytes (Fig. 3E, Ikesawa begins to modify the mineralogy and fabrics in subducting sediments et al. 2003, Austrheim and Andersen, 2004; Kitamura et al., 2005, very soon after burial (Moore et al., 1986; Vannucchi, 2019). Rowe et al., 2005, Andersen and Austrheim, 2006, Ujiie et al., 2007). At depths of ~5-10 km, subducting sediments begin to lithify Pseudotachylytes are rarely identified due to post-seismic alteration and subduction thrusts begin to lock and generate earthquakes and deformation (Kirkpatrick and Rowe, 2013; Phillips et al., 2019), (Fagereng, 2011, Almeida et al., 2018). In the plate boundary, but new methods for are expanding the possibilities of detecting mixed-mode deformation becomes prevalent and tectonic mélanges heat spikes caused by past seismic slip, including organic molecule form, with stiffer lithologies forming blocks within a finer grained, thermal maturity (Savage et al., 2014, Rabinowitz et al., 2020), fluid phyllosilicate-rich matrix (Fisher and Byrne, 1987; Byrne 1982, inclusion stretching (Ujiie et al. 2008), and clay metamorphism Kimura et al., 2012). At temperatures below ~350°C, most structural (Kameda et al., 2011). Brittle deformation is also evident in rocks fabrics are attributable to the action of more than one deformation exhumed from deeper within the subduction system. For example, mechanism acting in concert (Figs. 3A-C; e.g., dissolution- eclogite facies breccias have been linked to transient, periodic precipitation and both localized and distributed frictional sliding, intermediate-depth (80  km) rupture and associated fluid flow granular flow, and tensile fracturing; Rowe et al. 2011; Wassmann (Angiboust et al., 2012; Hertgen et al., 2017; Locatelli et al., 2018; and Stöckhert, 2013; Ujiie and Kimura, 2014; Fagereng and den Broadwell et al., 2019). Hartog, 2017). 58 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

In addition to evidence for past earthquakes, exhumed plate Understanding the effects of fluid-rock interaction (e.g. Miller et al., boundary faults and shear zones record evidence for mixed brittle- 2002) and structural modification during exhumation will elucidate ductile behavior that may correspond to geophysical observations the mechanisms of exhumation of subducted rocks which are critical of creep or slip transients such as episodic tremor and slip, across a to connecting them to the records of active subduction. variety of depth and temperature conditions. The ubiquity of these patterns suggests that diverse micromechanical processes may result Heading into the future in similar plate boundary behavior (Kirkpatrick et al., submitted). The mixed brittle-ductile behavior is recorded by block-in-matrix The many outstanding questions described above can be addressed fabrics with anastomosing fault systems. These geometries originate through future studies of exhumed rocks. Information about in shallowly subducted sediments when disruption of stratigraphic important earth processes can also be gained by exploring differences layers is driven by contrasts in strength and permeability: coarser between observations and modeling of active subduction zones and grained sandstones and volcanic rock experience consolidation, observations and modeling based on outcrop data. Areas of active cementation, fracturing and draining, while phyllosilicate-rich debate include questions of how the thermal structure of subduction layers of shale and altered basalt develop strong foliations which zones has changed over time (van Hunen and Moyen, 2012; Brown accommodate viscous creep (Fig. 3; Moore and Saffer, 2001, and Johnson, 2019; Palin et al., 2020) and how this change might affect Phillips et al., 2020). Block-in-matrix fabrics may also arise through the comparison between exhumed rocks and observations of active progressive, structurally controlled dehydration of blueschist to subduction. Another actively investigated question is whether the eclogite, or metamorphism of mixed lithologies which produce a process of exhumation itself impacts the rock record of subduction dramatic strength contrast (Hayman and Lavier, 2014, Behr et al., - through preferential return of samples or through exhumation- 2018, Kotowski and Behr, 2019). Vein patterns may record high related modification of subduction conditions (Penniston-Dorland and fluctuating pore pressure (Ujiie et al. 2018, Fagereng et al., et al., 2015; van Keken et al., 2018; Agard et al., 2018). Advances in 2018, Tarling et al., 2019) on short timescales (Fisher and Brantley, geochronology are revealing processes and timing of subduction 1992; 2014), which has been linked to tremor and slip in modern initiation (Mulcahy et al., 2018) and retrogression/exhumation subduction zones (Audet and Schaffer 2018). Studies of exhumed (Mulcahy et al. 2009; Bröcker et al., 2013). Shear stress on the plate faults have revealed the details of many processes, but outstanding interface at depth influences slip and creep, but we have few tools questions remain, such as how strain and stress are transferred from for interrogating shear or differential stress. It has been suggested deeper creeping zones to the seismogenic zone, how structures that mineral equilibria may be affected by differential stress, which control fluid flow and pore pressure, and how to characterize plate is not presently accounted for in pseudosection modeling but could boundary rheology and on what scales. potentially be leveraged as a paleopiezometer (Wheeler, 2018). Integrated structural and petrologic studies extend our capacity for Exhumation unraveling the deformational and metamorphic history (Pollok et al., 2008). In most subduction complexes, the mechanisms and pathways Many subduction complexes are well-known in the literature of exhumation of subducted oceanic crust are poorly known and (e.g., the Franciscan Complex in California, and Shimanto Belt this represents a growth opportunity for future studies. Models in Japan) but others have barely been explored (e.g., the Damara for exhumation include 1) underplating and exhumation due to Southern Zone in Namibia; Meneghini et al., 2014, and Gariep Belt extensional uplift and erosion (Platt, 1975; 1986), 2) return flow of in South Africa; Frimmel et al., 1996) and represent the possibility material along the plate boundary interface returning fragments of of using analog fossil subduction zones to understand individual metamorphosed oceanic slab to the trench (Cloos, 1982), and 3) modern plate boundaries. Future research should strive to better buoyancy-driven diapiric rise of high pressure blocks entrained in integrate data from rocks exhumed from fossil subduction systems serpentinite or mélange matrix (Takasu, 1989; Platt, 1993; Marschall with observations of active subduction, as these rocks provide and Schumacher, 2012). Evaluation of the exhumed rock record the perspective of longer timescales and shorter lengthscales suggests that exhumation occurs in short-lived episodes at varying inaccessible to methods of observing modern subduction systems. times during the life of a subduction zone (Agard et al., 2009, Guillot Collaborative training initiatives such as the E-FIRE project are a et al., 2009, Husson et al., 2009). Estimates for rates of exhumation great way to prepare future generations to work together to achieve vary but are typically less than plate velocities (Agard et al., 2009; these goals under the umbrella of interdisciplinary communities 2018) and few oceanic crustal rocks are recovered from depths >80 such as GeoPRISMS. km (Plunder et al., 2015). Recent advances in geochronology such as (U-Th)/He dating of magnetite (Cooperdock and Stockli, 2016), Acknowledgements Lu-Hf dating of lawsonite (Mulcahy et al., 2009), and Ar/Ar dating on various minerals (Rutte et al., 2020) allow geologists to determine The authors acknowledge helpful comments from Kayleigh Harvey, the timing of exhumation-related processes such as serpentinization Christiana Hoff, Will Hoover, Alissa Kotowski, James Kirkpatrick, and retrograde metamorphism. Peter van Keken. Previously unpublished photos were generously ■provided by Jay Ague, Åke Fagereng, Timm John, Jay Kaufman, Alissa Kotowski, and Kohtaro Ujiie. 59Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

References Abers, G.A. (2005). Seismic low-velocity layer at the top of subducting Bloch, W., T. John, J. Kummerow, P. Salazar, O.S. Krüger, S.A. Shapiro slabs: observations, predictions, and systematics. Phys Earth Planet (2018). Watching dehydration: Seismic indication for transient Inter, 149, 7-29 fluid pathways in the oceanic mantle of the subducting Nazca slab. Geochem Geophys, 19, doi.org/10.1029/2018GC007703 Agard, P., P. Yamato, L. Jolivet, E. Burov (2009). Exhumation of oceanic blueschists and eclogites in subduction zones: Timing and Broadwell, K.S., M. Locatelli, A. Verlaguet, P. Agard, M.J. Caddick (2019). mechanisms. Earth Sci Rev, 92, 1-2, 53-79 Transient and periodic brittle deformation of eclogites during intermediate-depth subduction. Earth Planet Sci Lett, 521, 91-102 Agard, P., P. Yamato, M. Soret, C. Prigent, S. Guillot, A. Plunder, B. Dubacq, A. Chauvet, P. Monié (2016). Plate interface rheological Bröcker, M., S. Baldwin, R. Arkudas (2013). The geological significance of switches during subduction infancy: Control on slab penetration and 40Ar/39Ar and Rb-Sr white mica ages from Syros and Sifnos, Greece: metamorphic sole formation. Earth Planet Sci Lett, 451, 208-220 A record of continuous (re)crystallization during exhumation? J Metamorph Geol, 31, 6, 629-646 Agard, P., A. Plunder, S. Angiboust, G. Bonnet, J. Ruh (2018). The subduction plate interface: Rock record and mechanical coupling Brown, M., T. Johnson (2019). MSA Presidential Address: Metamorphism (from long to short timescales). Lithos, 320-321, 537-566 and the evolution of subduction on Earth. Amer Miner, 104, 1065- 1082 Ague, J.J. (2007). Models of permeability contrasts in subduction zone mélange: Implications for gradients in fluid fluxes, Syros and Tinos Brown, K.M., M.D. Tryon, H.R. DeShon, L.M. Dorman, S.Y. Schwartz (2005). Islands, Greece. Chem Geol, 239, 3-4, 217-227 Correlated transient fluid pulsing and seismic tremor in the Costa Rica subduction zone. Earth Planet Sci Lett, 238, 189-203 Ague, J.J., S. Nicolescu (2014). Carbon dioxide released from subduction zones by fluid-mediated reactions. Nat Geosci, 7, 355-360 Byrne, T. (1982). Structural evolution of coherent terranes in the Ghost Rocks Formation, Kodiak Island, Alaska. Geol Soc London, Spec Pub, Almeida, R., E.O. Lindsey, K. Bradley, J. Hubbard, R. Mallick, E.M. Hill 10, 1, 229-242 (2018). Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on Chaudhuri, P., V. Mansard, A. Colin, L. Bocquet (2012). Dynamical flow near-trench coupling. Geophys Res Lett, 45, 4754-4763 arrest in confined gravity driven flows of soft jammed particles. Phys Rev Lett, 109, 3, 036001 Andersen, T.B., H. Austrheim (2006). Fossil earthquakes recorded by pseudotachylytes in mantle peridotite from the Alpine subduction Chester, F.M., J. Mori, N. Eguchi, S. Toczko, and the Expedition 343/343T complex of Corsica. Earth Planet Sci Lett, 242, 1-2, 58-72 Scientists (2013). Proc. IODP, 343/343T: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/​ Angel, R.J., M. Alvaro, R. Miletich, F. Nestola (2017a). A simple and iodp.proc.343343T.2013 generalised P-T-V Eos for structural phase transitions, implemented in EosFit and applied to quartz. Contrib Mineral Petrol, 172, 29- Cloos, M. (1982). Flow mélanges: Numerical modeling and geologic constraints on their origin in the Franciscan subduction complex, Angel, R.J., M.L. Mazzuchelli, M. Alvaro, F. Nestola (2017b). EosFit-Pinc: A California. Geol Soc Am Bull, 93, 4, 330-345 simple GUI for host-inclusion elastic thermobarometry. Amer Miner, 102, 1957-1960 Compton, K.E., J.D. Kirkpatrick, G.J. Holk (2017). Cyclical shear fracture and viscous flow during transitional ductile-brittle deformation in Angiboust, S., P. Agard, P. Yamato, H. Raimbourg (2012). Eclogite the Saddlebag Lake Shear Zone, California. Tectonophysics, 708, 1-14 breccias in a subducted ophiolite: A record of intermediate-depth earthquakes? Geology, 40, 707-710 Cooperdock, E.H.G., D.F. Stockli (2016). Unraveling alteration histories in serpentinites and associated ultramafic rocks with magnetite (U- Angiboust, S., J. Kirsch, O. Oncken, J. Glodny, P. Monié, E. Rybacki (2015). Th)/He geochronology. Geology, 44, 967-970 Probing the transition between seismically coupled and decoupled segments along an ancient subduction interface. Geochem Geophys, Cruz-Atienza, V.M., C. Villafuerte, H.S. Bhat (2018). Rapid tremor 16, 6, doi:10.1002/2015GC005776 migration and pore-pressure waves in subduction zones. Nat Communi, 9, 2900 Araki, E., D.M. Saffer, A.J. Kopf, L.M. Wallace, T. Kimura, Y. Machida, S. Ide, E. Davis, and the IODP Expedition 365 Shipboard Scientists Dasgupta, R., M.M. Hirschmann (2010). The deep carbon cycle and (2017). Recurring and triggered slow-slip events near the trench at melting in Earth’s interior. Earth Planet Sci Lett, 298, 1-13 the Nankai Trough subduction megathrust. Science 356, 6343, 1157- 1160 Davis, E., M. Heesemann, K. Wang (2011). Evidence for episodic aseismic slip across the subduction seismogenic zone off Costa Rica: CORK Audet, P., A.J. Schaeffer (2018). Fluid pressure and shear zone development borehole pressure observations at the subduction prism toe. Earth over the locked to slow slip region in Cascadia. Science Advances, 4, Planet Sci Lett, 306, 3-4, 299-305 3, doi: 10.1126/sciadv.aar2982 Davis, E., M. Kinoshita, K. Becker, K. Wang, Y. Asano, Y. Ito (2013). Episodic Austrheim, H., T.B. Andersen (2004). Pseudotachylytes from Corsica: deformation and inferred slow slip at the Nankai subduction Fossil earthquakes from a subduction complex. Terra Nova, 16, 4 zone during the first decade of CORK borehole pressure and VLFE monitoring. Earth Planet Sci Lett, 368, 110-118 Bebout, G.E., M.D. Barton (2002). Tectonic and metasomatic mixing in a high-T subduction zone melange - insights into the geochemical Debret, B., M. Andreani, M. Muñoz, N. Bolfan-Casanova, J. Carlut, C. evolution of the slab-mantle interface. Chem Geol, 187, 79-106 Nicollet, S. Schwartz, N. Trcera (2014). Evolution of Fe redox state in serpentine during subduction. Earth Planet Sci Lett, 400, 206-218 Bebout, G.E. (2007). Metamorphic chemical geodynamics of subduction zones. Earth Planet Sci Lett, 260, 373-393 Debret, B., M.-A. Millet, M.-L. Pons, P. Bouilhol, E. Inglis, H. Williams (2016). Isotopic evidence for iron mobility during subduction. Bebout, G.E. (2014). Chemical and isotopic cycling in subduction zones. In Geology, 44, 215-218 Treatise on Geochemistry 2nd edition, Elsevier, 4, 703-747 Dragovic, B., L.M. Samanta, E.F. Baxter, J. Selverstone (2012). Using garnet Bebout, G.E. S.C. Penniston-Dorland (2016). Fluid and mass transfer at to constrain the duration and rate of water-releasing metamorphic subduction interfaces – the field metamorphic record. Lithos, 240- reactions during subduction: An example from Sifnos, Greece. Chem 243, 228-258 Geol, 314-317, 9-22 Behr, W.M., J.P. Platt (2013). Rheological evolution of a Mediterranean Dragovic, B., E.F. Baxter, M.J. Caddick (2015). Pulsed dehydration subduction complex. J Struct Geol, 54, 136-155 and garnet growth during subduction revealed by zoned garnet geochronology and thermodynamic modeling, Sifnos, Greece. Earth Behr, W.M., A.J. Kotowski, K.T. Ashley (2018). Dehydration-induced Planet Sci Lett, 413, 111-122 rheological heterogeneity and the deep tremor source in warm subduction zones. Geology, 46, 5, 475-478 Elliott, T. (2003). Tracers of the slab. In: Inside the subduction factory, Geophysical Monograph 138, American Geophysical Union. 23-45 Bilek, S.L., T. Lay (2018). Subduction zone megathrust earthquakes. Geosphere, 14, 4, doi:10.1130/GES01608.1 60 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

Ernst, W.G. (1970). Tectonic contact between the Franciscan Mélange and of the Mt. Emilius klippe, Western Alps). Tectonophysics, 706-707, the Great Valley Sequence - Crustal expression of a Late Mesozoic 1-13 Benioff Zone. J Geophys Res, 75, 886-901 Hirth, G., S. Guillot (2013). Rheology and tectonic significance of serpentinite. Elements, 9, 2, 107-113 Ernst, W.G. (1971). Do mineral parageneses reflect unusually high- Husson, L., J.-P. Brun, P. Yamato, C. Faccenna (2009). Episodic slab rollback pressure conditions of Franciscan metamorphism? Amer J Sci, 270, fosters exhumation of HP-UHP rocks. Geophys J Int, 179, 3, 1292- 81-108 1300 Hyndman, R.D., M. Yamano, D.A. Oleskevich (1997). The seismogenic Evans, K.A., A.G. Tompkins, J. Cliff, M.L. Florentini (2014). Insights into zone of subduction thrust faults. The Island Arc, 6, 244-260 subduction zone sulfur recycling from isotopic analysis of eclogite- Iacovino, K., M.R. Guild, C.B. Till (2020). Aqueous fluids are effective hosted sulfides. Chem Geol 365, 1-19 oxidizing agents of the mantle in subduction zones. Contrib Mineral Petrol, 175, 36 Fagereng, Å., F. Remitti, R.H. Sibson (2010). Shear veins observed within Ikesawa, E., A. Sakaguchi, G. Kimura (2003). Pseudotachylyte from an anisotropic fabric at high angles to the maximum compressive ancient accretionary complex: Evidence for melt generation during stress. Nat Geosci, 3, 482-485 seismic slip along a master décollement. Geology, 31, 7, 637–640 Iyer, K., L.H. Rüpke, J. Phipps Morgan, I. Gervemeyer (2012). Controls of Fagereng, Å. (2011). Geology of the seismogenic subduction thrust faulting and reaction kinetics on serpentinization and double Benioff interface. Geol Soc of London Spec Pub, 359, 1, 55-76 zones. Geochem Geophys, 13, 9 Jarrard, R.D. (2003). Subduction fluxes of water, carbon dioxide, chlorine Fagereng, Å., J.F.A. Diener (2011). Non-volcanic tremor and discontinuous and potassium. Geochem Geophys, 4, 5 slab dehydration. Geophys Res Lett, 38, 5 John, T., N. Gussone, Y.Y. Podladchikov, G.E. Bebout, R. Dohmen, R. Halama, R. Klemd, T. Magna, H.-M. Seitz (2012). Volcanic arcs fed Fagereng, Å., G.W.B. Hillary, J.F.A. Diener (2014). Brittle-viscous by rapid pulsed fluid flow through subducting slabs. Nat Geosci, 5, deformation, slow slip, and tremor. Geophys Res Lett, 41, 4159-4167 489-492 Kameda, J., K. Ujiie, A. Yamaguchi, G. Kimura (2011). Smectite to chlorite Fagereng, Å., S.A.M. Den Hartog (2017). Subduction megathrust creep conversion by frictional heating along a subduction thrust. Earth governed by pressure solution and frictional viscous flow. Nat Planet Sci Lett, 305, 1-2, 161-170 Geosci, 10, 1, 51-57 Karig, D.E. (1990). Experimental and observational constraints on the mechanica behavior in the toes of accretionary prisms. Geol Soc of Fagereng, Å., J.F.A. Diener, F. Meneghini, C. Harris (2018). Quartz vein London Spec Pub, 54, 383-398, doi:10.1144/GSL.SP.1990.054.01.35 formation by local dehydration embrittlement along the deep, Kastner, M., E.A. Solomon, R.N. Harris, M.E. Torres (2014). Fluid origins, tremorgenic subduction interface. Geology, 46, 1, 67-70 thermal regimes, and fluid and solute fluxes in the forearc of subduction zones. In Developments in Marine Geology, 7, 671-733 Fagereng, Å., et al. and the IODP Expedition 372/375 Scientists (2019). Kato, A., A. Sakaguchi, S. Yoshida, H. Yamaguchi, Y. Kaneda (2004). Mixed deformation styles observed on a shallow subduction thrust, Permeability structure around an ancient exhumed subduction-zone Hikurangi margin, New Zealand. Geology, 47, 9, 872-876 fault. Geophys Res Lett, 31, L06602, doi:10.1029/2003GL019183 Kawamura, K., Y. Ogawa, H. Hara, R. Anma, Y. Dilek, S. Kawakami, S. Fisher, D.M., T. Byrne (1987). Structural evolution of underthrusted Chinyonobu, H. Mukoyoshi, S. Hirano, I. Motoyama (2011). Rapid sediments, Kodiak Islands, Alaska. Tectonics, 6, 6, 775-793 exhumation of subducted sediments along an out-of-sequence thrust in the modern eastern Nankai accretionary prism. In: Ogawa, Y., Fisher, D.M., S.L. Brantley (1992). Models of quartz overgrowth and Anma, R., Dilek, Y. (eds) Accretionary Prisms and Convergent Margin vein formation: Deformation and episodic fluid flow in an ancient Tectonics in the Northwest Pacific Basin. Modern Approaches in subduction zone. J Geophys Res, 97, B13 20043-20061 Solid Earth Sciences, 8, Springer, Dordrecht, 215-227 Kelemen, P.B., C.E. Manning (2015). Reevaluating carbon fluxes in Fisher, D.M., S.L. Brantley (2014). The role of silica redistribution in the subduction zones, what goes down, mostly comes up. Proceedings evolution of slip instabilities along subduction interfaces: Constraints of the National Academy of Sciences, doi:10.1073/pnas.1507889112 from the Kodiak accretionary complex, Alaska. J Struct Geol, 69, 395- Kelley, K.A., E. Cottrell (2009). Water and the oxidation state of subduction 414 zone magmas. Science, 325, 605–607 Kim, D., I. Katayama, K. Michibayashi, T. Tsujimori (2012). Rheological Frezzotti, M.L., J. Selverstone, Z.D. Sharp, R. Compagnoni (2011). contrast between glaucophane and lawsonite in naturally deformed Carbonate dissolution during subduction revealed by diamond- blueschist from Diablo Range, California. Island Arc, 22, 1, 63-73 bearing rocks from the Alps. Nat Geosci, 4, 703-706 Kimura, G., A. Yamaguchi, M. Hojo, Y. Kitamura, J. Kameda, K. Ujiie, Y. Hamada, M. Hamahashi, S. Hina (2012). Tectonic mélange as fault Frimmel, H.E., C.J.H. Hartnady, F. Koller (1996). Geochemistry and tectonic rock of subduction plate boundary. Tectonophysics, 568, 25-38 setting of magmatic units in the Pan-African Gariep Belt, Namibia. Kirkpatrick, J.D., D. Shelly, Å. Fagereng submitted. Geologic constraints Chem Geol, 130, 1-2 101-121 on the mechanisms of slow earthquakes. Nat Rev: Earth and Environment Fukuchi, R., K. Fujimoto, J. Kameda, M. Hamahashi, A. Yamaguchi, G. Kirkpatrick, J.D., C.D. Rowe (2013). Disappearing ink: How Kimura, Y. Hamada, Y. Hashimoto, Y. Kitamura, S. Saito (2014). pseudotachylytes are lost from the rock record. J Struct Geol Changes in illite crystallinity within an ancient tectonic boundary Kitamura, Y., et al. (2005). Mélange and its seismogenic roof décollement: thrust caused by thermal, mechanical, and hydrothermal effects: an a plate boundary fault rock in the subduction zone – An example example from the Nobeoka Thrust, southwest Japan. Earth, Planets from the Shimanto Belt, Japan. Tectonics. 24, 5, 1–15 and Space, 66, 116 Kotowski, A.J., W.M. Behr (2019). Length scales and types of heterogeneities along the deep subduction interface: Insights from Gao, X., K. Wang (2018). Rheological separation of the megathrust exhumed rocks on Syros Island, Greece. Geosphere, 15, 4, 1038-1065 seismogenic zone and episodic tremor and slip. Nature, 543, 416- Lanari, P., O. Vidal, V. De Andrade, B. Dubacq, E. Lewin, E.G. 419 Grosch, S. Schwartz (2014). XMapTools: A MATLAB©-based program for electron microprobe X-ray image processing and Gerrits, A.R., E.C. Inglis, B. Dragovic, P.G. Starr, E.F. Baxter, K.W. Burton geothermobarometry. Comput and Geosci, 62, 227-240 (2019). Release of oxidizing fluids in subduction zones recorded by Lanari, P., M. Engi (2017). Bulk composition effects on metamorphic iron isotope zonation in garnet. Nat Geosci, 12, 1029-1033 mineral assemblages. Rev Mineral Geochem, 83, 55-102 Gerya, T. (2011). Future directions in subduction modeling. J Geodyn, 52, 5, 344-378 Gratier, J.-P., F. Renard, P. Labaume (1999). How pressure solution creep and fracturing processes interact in the upper crust to make it behave in both a brittle and viscous manner. J Struct Geol, 21, 1189-1197 Guillot, S., K. Hattori, P. Agard, S. Schwartz, O. Vidal (2009). Exhumation processes in oceanic and continental subduction contexts: A review. In: Lallemand, S., and Funiciello, F., eds, Subduction Zone Geodynamics, Springer-Verlag Berlin Heidelberg Hacker, B (2008). H2O subduction beyond arcs. Geochem Geophys, 9, 3 Hashimoto, Y., N. Yamano (2014). Geological evidence for shallow ductile- brittle transition zones along subduction interfaces: Example from the Shimanto Belt, SW Japan. Earth, Planets and Space, 66, 141 Hayman, N.W., L.L. Lavier (2014). The geologic record of deep episodic tremor and slip. Geology, 42, 3, 195-198 Hertgen, S., P. Yamato, L.F.G. Morales, S. Angiboust (2017). Evidence for brittle deformation events at eclogite-facies P-T conditions (example 61Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Locatelli, M., A. Verlaguet, P. Agard, L. Federico, S. Angiboust (2018). Penniston-Dorland, S.C., M.J. Kohn, C.E. Manning (2015). The global range Intermediate-depth brecciation along the subduction plate interface of subduction zone thermal structures from exhumed blueschists (Monviso eclogite, W. Alps). Lithos, 320-321, 378-402 and eclogites: Rocks are hotter than models. Earth Planet Sci Lett, 428, 243-254 Marschall, H.R., J.C. Schumacher (2012). Arc magmas sourced from melange diapirs in subduction zones. Nat Geosci, 5, 862-867 Platt, J.P. (1975). Metamorphic and deformational processes in the Franciscan Complex, California: Some insights from the Catalina Maruyama, S., J.G. Liou, Y. Sasakura (1985). Low-temperature Schist terrane. Geol Soc Am Bull, 86, 1337-1347 recrystallization of Franciscan greywackes from Pacheco Pass, California. Mineral Mag, 49, 352, 345-355 Platt, J.P. (1986). Dynamics of orogenic wedges and the uplift of high- pressure metamorphic rocks. Geol Soc Am Bull, 97, 1037-1053 Meneghini, F., J.C. Moore (2007). Deformation and hydrofracture in a subduction thrust at seismogenic depths: The Rodeo Cove thrust Platt, J.P. (1993). Exhumation of high pressure rocks: A review of concepts zone, Marin Headlands, California. Geol Soc of America Bulletin, and processes. Terra nova, 5, 119-133 119, 1/2, 174-183 Phillips, N.J., C.D. Rowe, K. Ujiie (2019). For how long are pseudotachylytes Meneghini, F., A. Kisters, I. Buick, Å. Fagereng (2014). Fingerprints of late strong? Rapid alteration of basalt-hosted pseudotachylytes from a Neoproterozoic ridge subducting in the Pan-African Damara belt, shallow subduction complex. Earth Planet Sci Lett, 518, 108-115 Namibia. Geology, 42, 10, 903-906 Phillips, N.J., G. Motohashi, K. Ujiie, C.D. Rowe (2020). Evidence of Menzel, M.D., C.J. Garrido, V. López Sánchez-Vizcaíno (2020). Fluid- localized failure along altered basaltic blocks in tectonic mélange at mediated carbon release from serpentinite-hosted carbonates the updip limit of the seismogenic zone: Implications for the shallow during dehydration of antigorite-serpentinite in subduction zones. slow earthquake source. Geochem Geophys, 21, e2019GC08839 Earth Planet Sci Lett, 531, 115964 Piccoli, F., A. Vitale Brovarone, O. Beyssac, I. Martinez, J.J. Ague, C. Mihalynuk, M.G., P. Erdmer, E.D. Ghent, F. Cordey, D.A. Archibald, R.M. Chaduteau (2016). Carbonation by fluid-rock interactions at high- Friedman, R. M., G.G. Johnson (2004). Coherent French Range pressure conditions: Implications for carbon cycling in subduction blueschist: Subduction to exhumation in <2.5 MY? Geol Soc of zones. Earth Planet Sci Lett, 445, 146-159 America Bulletin, 116, 7-8, 910-922 Plümper, O., T. John, Y.Y. Podladchikov, J.C. Vrijmoed (2017). Fluid escape Miller, J.A., I.S. Buick, I. Cartwright, A. Barnicoat (2002). Fluid processes from subduction zones controlled by channel-forming reactive during the exhumation of high-P metamorphic belts. Mineral Mag, porosity. Nat Geosci, 10, 150-156 66, 1, 93-119 Pollok, K., G.E. Lloyd, H. Austrheim, A. Putnis (2008). Complex replacement Miyashiro, A. (1973). Paired and unpaired metamorphic belts. patterns in garnets from Bergen Arcs eclogites: A combined EBSD Tectonophysics and analytical TEM study. Geochemistry 68, 2, 177-191 Moore, J.C., A. Allwardt (1980). Progressive deformation of a Tertiary Polonia, A., et al. (2017). Lower plate serpentinite diapirism in the trench slope, Kodiak Islands, Alaska. J Geophys Res, 85, B9, 4741- Calabrian Arc subduction complex. Nat Communi, 8, 2172 4756 Pons, M.-L., B. Debret, P. Bouilhol, A. Delacour, H. Williams (2016). Zinc Moore, J.C., S. Roeske, N. Lundberg, J. Schoonmaker, D.S. Cowan, E. isotope evidence for sulfate-rich fluid transfer across subduction Gonzales, S.E. Lucas (1986). Scaly fabrics from Deep Sea Drilling zones. Nat Communi, DOI: 10.1038/ncomms13794 Project cores from forearcs. In: Moore, J. C. (ed) Structural Fabrics in Deep Sea Drilling Project Cores from Forearcs. Geol Soc of America Plunder, A., P. Agard, C. Chopin, A. Pourteau, A.I. Okay (2015). Accretion, Memoir, 166, 55-74 underplating and exhumation along a subduction interface: From subduction initiation to continental subduction (Tavşanli zone, W. Moore, J.C., D. Saffer (2001). Updip limit of the seismogenic zone beneath Turkey). Lithos, 226, 233-254 the accretionary prism of southwest Japan: An effect of diagenetic to low-grade metamorphic processes and increasing effective stress. Rabinowitz, H.S., H.M. Savage, P.J. Polissar, C.D. Rowe, J.D. Kirkpatrick Geology, 29, 2, 183-186 (2020). Earthquake slip surfaces identified by biomarker thermal maturity within the 2011 Tohoku-Oki earthquake fault zone. Nat Moore, J.C., C. Rowe, F. Meneghini (2007). How accretionary prisms Communi, 11, 1, 1-9 elucidate seismogenesis in subduction zones. In: Dixon, T. H. and Moore, J. C., eds., The Seismogenic Zone of Subduction Thrust Faults. Regalla, C.A., C.D. Rowe, N. Harrichhausen, M.S. Tarling, J. Singh (2018). Columbia University Press, 288-315 Styles of underplating in the Marin Headlands terrane, Franciscan complex, California. In: Geology and Tectonics of Subduction Zones: Mulcahy, S., R.L. King, J.D. Vervoort (2009). Lawsonite Lu-Hf geochronology: A Tribute to Gaku Kimura. Geol Soc of Spec Paper, 534, 155-173 A new geochronometer for subduction zone processes. Geology, 37, 11, 987-990 Ring, U., M.T. Brandon (1994). Kinematic data for the Coast Range fault and implications for exhumation of the Franciscan subduction Mulcahy, S., J. Starnes, H.W. Day, M.A. Coble, J.D. Vervoort (2018). Early complex. Geology, 22, 8, 735-738 onset of Franciscan subduction. Tectonics, 37, 1194-1209 Rondenay, S., G.A. Abers, P.E. van Keken (2008). Seismic imaging of Nielsen, S.G., H.R. Marschall (2017). Geochemical evidence for mélange subduction zone metamorphism. Geology, 36, 4, 275-278 melting in global arcs. Science Advances, 3:e1602402 Rowe, C.D., J.C. Moore, F. Meneghini, A.W. McKiernan (2005). Large- Nishiyama, N., H. Sumino, K. Ujiie (2020). Fluid overpressure in subduction scale pseudotachylytes and fluidized cataclasites from an ancient plate boundary caused by mantle-derived fluids. Earth Planet Sci subduction thrust fault. Geology, 33, 12, 937–940 Lett, 538, 116199 Rowe, C.D., F. Meneghini, J.C. Moore (2011). Textural record of the seismic Palin, R.M., M. Santosh, W. Cao, S. Li, D. Hernandez-Uribe, A.J. Parsons cycle: Strain-rate variation in an ancient subduction thrust. Geol Soc, (2020). Secular metamorphic change and the onset of plate London, Spec Pub, 359, 77-95 tectonics. Earth-Science Reviews Rowe, C.D., J.C. Moore, F. Remitti, and the IODP Expedition 343/343T Peacock, S.M., R.D. Hyndman (1999). Hydrous minerals in the mantle Scientists (2013). The thickness of subduction plate boundary faults wedge and the maximum depth of subduction thrust earthquakes. from the seafloor into the seismogenic zone. Geology, 41, 991-994 Geophys Res Lett, 26, 16, 2517-2520 Rutte, D., J. Garber, A.R.C. Kylander-Clark, P.R. Renne (2020). An Peng, Z., J. Gomberg (2010). An integrated perspective of the continuum exhumation pulse from the nascent Franciscan subduction zone between earthquakes and slow-slip phenomena. Nat Geosci, 3, 599- (California, USA). Tectonics, 39, 10 607 Saffer, D.M., H.J. Tobin (2011). Hydrogeology and the mechanics of Penniston-Dorland, S.C., S.S. Sorensen, R.D. Ash, S.V. Khadke (2010). subduction zone forearcs: Fluid flow and pore pressure. Ann Rev Lithium isotopes as a tracer of fluids in a subduction zone mélange: Earth Planet Sci, 39, 157-186 Franciscan Complex, CA. Earth Planet Sci Lett, 292, 181-190, doi:10.1016/j.epsl.2010.01.034 Saffer, D.M., L.M. Wallace, K. Petronotis, and the Expedition 375 Scientists (2018). Expedition 375 Preliminary Report: Hikurangi Subduction Penniston-Dorland, S.C., J.K. Gorman, G.E. Bebout, P.M. Piccoli, R.J. Walker Margin Coring and Observatories. International Ocean Discovery (2014) Reaction rind formation in the Catalina Schist: Deciphering Program. doi.org/​10.14379/i​odp.pr.375.2018 a history of mechanical mixing and metasomatic alteration, Chem Geol, 384, 47-61 Sakaguchi, A., et al. (2011). Seismic slip propagation to the update end of plate boundary subduction interface faults: Vitrinite reflectance 62 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

geothermometry on Integrated Ocean Drilling Program NanTroSEIZE 111-114 cores. Geology, 39, 4, 395-398 Ujiie, K., G. Kimura (2014). Earthquake faulting in subduction zones: Savage, H.M., P.J. Polissar, R. Sheppard, C.D. Rowe, E.E. Brodsky (2014). Biomarkers heat up during earthquakes: New evidence of seismic Insights from fault rocks in accretionary prisms. Progress in Earth slip in the rock record. Geology, 42, 2, 99-102 and Planetary Science, 1, 1, 7 Scambelluri, M., G.E. Bebout, D. Belmonte, M. Gilio, N. Campomenosi, Ujiie, K., H. Saishu, Å. Fagereng (2018). An explanation of episodic tremor N. Collins, L. Crispini (2016). Carbonation of subduction-zone and slow slip constrained by crack-seal veins and viscous shear in serpentinite (high-pressure ophicarbonate; Ligurian Western Alps) subduction mélange. Geophys Res Lett, 45, 11, 5371-5379 and implications for deep carbon cycling. Earth Planet Sci Lett, 441, Underwood, M.B. (1989). Temporal changes in geothermal gradient, 155-166 Franciscan subduction complex, Northern California. J Geophys Res, Shiina, T., J. Nakajima, T. Matsuzawa (2013). Seismic evidence for high 94, B3, 3111-3125 pore pressures in the oceanic crust. Implications for fluid-related van Hunen, J., J.-F. Moyen (2012). Archean subduction: fact or fiction? embrittlement. Geophys Res Lett, 40, 2006-2010 Ann Rev Earth Planet Sci, 40, 195-219 Sibson, R. (1989). Earthquake faulting as a structural process. J Struct van Keken, P.E., B.R. Hacker, E.M. Syracuse, G.A. Abers (2011). Subduction Geol, 11, 1-2, 1-14 factory: 4. Depth-dependent flux of H2O from subducting slabs Spence, W. (1987). Slab pull and the seismotectonics of subducting worldwide. J Geophys Res, 116, B01401 lithosphere. Rev Geoph, 25, 1, 55-69 van Keken, P.E., S. Kita, J. Nakajima (2012). Thermal structure and Spinelli, G.A., D.M. Saffer, M.B. Underwood (2006). Hydrogeologic intermediate-depth seismicity in the Tohoku-Hokkaido subduction responses to three-dimensional temperature variability, zones. Solid Earth, 3, 355–364 Costa Rica subduction margin. J Geophys Res, 111, B04403, van Keken, P.E., I. Wada, G.A. Abers, B.R. Hacker, K. Wang (2018). doi:10.1029/2004JB003436 Mafic high-pressure rocks are preferentially exhumed from warm Stewart, E.M., J.J. Ague, J.M. Ferry, C.M. Schiffries, R.-B. Tao, T.T. Isson, subduction settings. Geochem Geophys, 19, 2934-2961, doi N.J. Planavsky (2019). Carbonation and decarbonation reactions: 10.1029/2018GC007624 Implications for planetary habitability. Amer Miner, 104, 1369-1380 Vannucchi, P., A. Maltman, G. Bettelli, B. Clennell (2003). On the nature of Stöckhert, B., M. Wachmann, M. Küster, S. Bimmermann (1999). Low scaly fabric and scaly clay. J Struct Geol, 25, 5, 673-688 effective viscosity during high pressure metamorphism due to Vannucchi, P (2019). Scaly fabric and slip within fault zones. Geosphere, dissolution precipitation creep: The record of HP-LT metamorphic 15, 2, 342-356 carbonates and siliciclastic rocks from Crete. Tectonophysics, 303, Vrolijk, P. (1987). Tectonically driven fluid flow in the Kodiak accretionary 299-319 complex, Alaska. Geology, 15, 5, 466-469 Taetz, S., T. John, M. Bröcker, C. Spandler, A. Stracke (2018). Fast intraslab Vrolijk, P., G. Myers, J.C. Moore (1998). Warm fluid migration along fluid-flow events linked to pulses of high pore fluid pressure at the tectonic melanges in the Kodiak Accretionary Complex, Alaska. J subducted plate interface. Earth Planet Sci Lett, 482, 33-43 Geophys Res, 93, B9, 10313-10324 Takasu, A. (1989). P-T histories of peridotite and amphibolite tectonic Walters, J.B., A.M. Cruz-Uribe, H.R. Marschall (2020). Sulfur loss from blocks in the Sanbagawa metamorphic belt, Japan. In Daly, J.S., Cliff, subducted and altered oceanic crust and implications for mantle R.A., Yardley, B.W.D. (eds), Evolution of Metamorphic Belts, Geol Soc oxidation. Geochem Pers Lett, 13, 36-41 Spec Pub, 43, 553-538 Wang, K., Y. Hu, J. He, (2012). Deformation cycles of subduction Tarling, M.S., S.A.F. Smith, J.M. Scott (2019). Fluid overpressure from earthquakes in a viscoelastic Earth. Nature, 484, 327-332 chemical reactions in serpentinite within the source region of deep Wassmann, S., B. Stöckhert (2013). Rheology of the plate interface -- episodic tremor. Nat Geosci, 12, 1034-1042 Dissolution precipitation creep in high pressure metamorphic rocks. Tembayashi, M., S. Maruyama, J.G. Liou (1996). Thermobaric structure of Tectonophysics, 608, 1-29 the Franciscan Complex in the Pacheco Pass region, Diablo Range, Wheeler, J. (1992). Importance of pressure solution and coble creep in California. The J Geol, 104, 5, 617-636 the deformation of polymineralic rocks. J Geophys Res, 97, B4, 4579- Tobin, H., et al. and the Expedition 358 Scientists (2019). Expedition 4586 358 Preliminary Report: NanTroSEIZE Plate Boundary Deep Riser Wheeler, J. (2018). The effects of stress on reactions in the Earth: 4: Nankai Seismogenic/Slow Slip Megathrust. International Ocean Sometimes rather mean, usually normal, always important. J Discovery Program. doi.org/​10.14379/i​odp.pr.358.2019 Metamorph Geol, 36, 4, 439-461 Tollan, P., J. Hermann (2019). Arc magmas oxidized by water dissociation Xing, T., W. Zhu, M. French, B. Belzer (2019). Stabilizing effect of high pore and hydrogen incorporation in orthopyroxene, Nat Geosci, 12, 667- fluid pressure on slip behaviors of gouge-bearing faults. J Geophys 671 Res, 124, 9, 9526-9545 Tomkins, H.S., R. Powell, D.J. Ellis (2007). The pressure dependence of the Yamaguchi, A., K. Ujiie, S. Nakai, G. Kimura, (2012). Sources and zirconium-in-rutile thermometer. J Metamorph Geol, 25, 703-713 physicochemical characteristics of fluids along a subduction-zone Ujiie, K., H. Yamaguchi, A. Sakaguchi, S. Toh (2007). Pseudotachylytes in an megathrust: A geochemical approach using syn-tectonic mineral ancient accretionary complex and implications for melt lubrication veins in the Mugi mélange, Shimanto accretionary complex. during subduction zone earthquakes. J Struct Geol, 29, 4, 599–613 Geochem Geophys, 13, 7, doi:10.1029/2012GC004137 Ujiie, K., A. Yamaguchi, S. Taguchi (2008). Stretching of fluid inclusions in Zack T., J. John (2007). An evaluation of reactive fluid flow and trace calcite as an indicator of frictional heating on faults. Geology, 36, 2, element mobility in subducting slabs. Chem Geol, 239, 199-216 63Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Science Reviews Under the volcano: Tracing the path of eruptible arc magmas Daniel Rasmussen (National Museum of Natural History, Smithsonian Institution) and Megan Newcombe (University of Maryland) As you read this article, there are 40-50 volcanoes erupting BAROMETERS CHRONOMETERS (www.volcano.si.edu). These eruptions have profound implications for hazards (Cameron et al. 2018; Roman (1) Jd in clinopyroxene MohoMid crustal Pre-eruptivestaging B (1) H in olivine and Cashman 2018; Power et al. 2020), formation and evolution (2) MI entrapment A of crust (Cai et al. 2015; Morris et al. 2019), climate and volatile (3) MI equil. Minutes to hours cycling (Kelemen and Manning 2015; Aiuppa et al. 2019; Fischer tinitial et al. 2019), and ore deposits (Zajacz et al. 2010; Wilkinson 2013; Blundy et al. 2015), and they enable Earth Scientists to peer deep H2O tquench into Earth (Turner et al. 2016; Till et al. 2019). Understanding the volcanic process is of fundamental importance, and the study of AB the architecture of crustal magmatic systems is key to achieving Distance from rim this goal. Magmatic plumbing systems may be understood, in part, from investigation of magma storage depth, which relates closely to storage (2) Mg in plagioclase eruptibility (Moran et al. 2011; Degruyter and Huber 2014; Huber et al. 2019), crustal structure (Janiszewski et al. 2013; Crosbie et al. Days to years 2019), and magmatic differentiation (Zimmer et al. 2010; Husen et al. 2016). Because many magmatic systems are thought to be dynamic AB MgO tinitial in nature, determining the timescales of magmatic processes is also tquench crucial to understanding magmatic plumbing systems. Deep crustal storage B AB A Distance from rim Mg# (3) Fe-Mg in cpx Months to decades tinitial tquench In the decade since the inception of GeoPRISMS, we have AB significantly improved our understanding of the depths and rates Distance from rim of magmatic processes occurring in the crust. Large-scale research platforms have enabled data collection at an unprecedented level Figure 1. Combined chronometry and barometry approach to of detail, and have facilitated collaborations across disciplines understanding magmatic plumbing systems. and institutions. One prime example is the joint GeoPRISMS and EarthScope iMUSH experiment (Hansen et al. 2016; Kiser et al. Improved microanalytical techniques now enable the high-precision 2016; Kiser et al. 2019; Ulberg et al. 2020). Another is the set of 2015 analysis of major, volatile, and trace elements at the micron scale (Le field campaigns in the Aleutians, which brought together scientists Voyer et al. 2014; Lloyd et al. 2014; Saunders et al. 2014; Ubide et from GeoPRISMS, the Alaska Volcano Observatory, and the Deep al. 2015). Crystal clocks, which are geochemical tools based on the Carbon Observatory. Concurrent with large-scale community principle of diffusion, have come of age, and are increasingly used for experiments have been advancements in methods of data collection determining rates of magmatic processes over timescales of minutes and analysis. Novel seismic experiments have been conducted, such to thousands of years (Rosen 2016), and our geobarometric tools as the deployment of large geophone arrays (Hansen and Schmandt have been honed (Fig. 1; Neave and Putirka 2017; Rasmussen et al. 2015; Glasgow et al. 2018), and we are now able to perform full- 2020). The growing body of observations using such techniques in waveform inversions of infrasonic data with topography, thereby the study of experimental and natural systems has been codified by enabling estimates of volume flow rate (Kim et al. 2015; Fee et al. recent reviews (Bergantz et al. 2015; Cashman et al. 2017). Together, 2017b). The development of Multi-component Gas Analyzer System we are now able to peer into magmatic plumbing systems and place (MultiGAS) instruments enables the measurement of different gas magmas in both time and space. In this article we highlight a few species simultaneously, ushering in a new era for studies of magmatic of the areas of significant progress from GeoPRISMS and related systems (Aiuppa et al. 2005; Shinohara 2005). research, and we identify areas for future work. We focus on arc magmatism, as arcs are where most subaerial volcanism occurs. 64 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

What is the rate of mantle-derived al. 2014; Mironov et al. 2015; Moore et al. 2015; Wallace et al. 2015; magma production at arcs? Rasmussen et al. 2020), increasing depth estimates by up to a factor of two (Rasmussen et al., 2020). Finally, multi-disciplinary studies The supply of mantle-derived magma ultimately drives volcanic of magma depth, perhaps the best means for progress, are becoming eruptions (Poland et al. 2012; Sides et al. 2014) and controls crustal increasingly prevalent (Aiuppa et al. 2010; Rasmussen et al. 2018b; production at arcs (Vogt et al. 2012; Till et al. 2019). Quantification DeGrandpre and Le Mével 2019; Werner et al. 2020). of the rate of magma supply from the mantle to the base of the crust The first stage of crustal transport of mantle-derived melts may requires estimations of erupted and intruded magma volumes, and be storage in lower crustal processing zones, referred to as MASH rates of crustal erosion. These parameters are notoriously difficult (Melting, Assimilation, Storage, and Homogenization; Hildreth to estimate, but much progress has been made via the study of and Moorbath 1988) or hot zones (Annen et al. 2006). Here exposed crustal sections (DeBari and Greene 2011; Kay et al. 2019; magmas may undergo an initial phase of differentiation. Typically, Morris et al. 2019), lower-crustal xenoliths (Rudnick and Goldstein such regions are envisioned to occur in the lower crust because 1990; Yogodzinski and Kelemen 2007) and from seismic surveys elevated temperatures make them more easily maintained over long (Shillington et al. 2004; Janiszewski et al. 2013; Shillington et al. timescales (Annen et al., 2006) and geochemical evidence may point 2013). Radiometric dating can be combined with estimates of crustal to the lower crust (Hildreth and Moorbath, 1988). In recent years, composition and structure to estimate time-averaged magma supply this model has been expanded. Differentiation is often considered rates (Jicha et al. 2006; Jicha and Jagoutz 2015; Ducea et al. 2017). to occur at various depths in the crustal column (Putirka 2017), and Alternatively, time-averaged magma supply rates can be estimated by magmatic systems that seamlessly span much of the length of the pairing measurements of SO2 fluxes from volcanoes with estimates crust have been proposed (Cashman et al., 2017). However, evidence of primary magma sulfur concentrations derived from analyses of exists that underscores the importance of lower crustal storage in primitive melt inclusions (Werner et al. 2020). Estimates of magma some locations. Evidence is strong in areas of thick crust, such as supply rates can then be combined with estimates of extruded magma central Chile (Hildreth and Moorbath, 1988) and Taupo (Rocco et volumes (Werner et al. 2017) to calculate the ratio of intruded to al. 2019). Additional evidence comes from studying exposed arc extruded magma volume; e.g., Werner et al. (2020) use this approach crustal sections, such as the Famatinian, Kohistan, and Talkeetna to estimate an intrusive to extruded magma volume ratio of 13:1 at arcs (DeBari and Greene 2011; Walker Jr et al. 2015). As seismic and Mt. Cleveland, Alaska. electromagnetic techniques improve, it is now possible to see through upper- and mid-crustal magma bodies into the lower crust and find What controls the rate of magma production at subduction evidence for deep zones of melt collection. Slow seismic and/or zones? The age, temperature, incoming plate velocity, slab dip, and conductive anomalies, consistent with regions of melt accumulation, hydration state of the slab are all considered to be important factors have been found at several locations, such as Mount St. Helens (Syracuse and Abers 2006; van Keken et al. 2011). The spatio- (Kiser et al. 2016; Bedrosian et al. 2018), Puna Plateau (Delph et al. temporal variability in magma supply rates and primitive melt 2017), and Cleveland volcano (Janiszewski et al. 2020). While our compositions may manifest as along-arc volcanic variability. ability to identify such regions has grown, questions remain about However, the relative importance of mantle versus crustal control the prevalence of such lower crustal processing zones, particularly of along-arc volcanic variability remains a frontier problem in in regions of relatively thin crust, such as island-arc settings. subduction zone science (Till et al. 2019). The vast majority of magma storage regions identified with geophysical and geochemical techniques are in the mid to upper Where is magma stored and processed in the crust? crust. A key area of recent focus has been studying magma storage regions below caldera systems. These systems tend to Prior to their eruption at the surface, mantle-derived magmas be characterized by shallow magma storage (<5 km below the must travel through crustal plumbing systems. In the last surface); examples include Okmok (Hart et al. 2018; Miller decade, our ability to identify and characterize such regions has et al. 2018), Taupo (Harmon et al. 2019), Fisher (Mann and grown substantially. Geodetic methods have seen significant Freymueller 2003), and Masaya (Stephens and Wauthier 2018). advancements, particularly in data collection (Ebmeier et al. 2019) However, exceptions to shallow storage exist (DeGrandpre et al. and computational techniques (Anantrasirichai et al. 2019; Reath et 2017; Jiang et al. 2018; Gottsmann et al. 2020). Another area of al. 2019; Sun et al. 2019). New satellite technology, exemplified by focus has been understanding how magmatic plumbing systems Sentinel-1 and satellite constellations, offers improved coverage and evolve during the lead-up to eruption, demonstrating their repeat intervals, enabling large-scale studies of volcanoes (Ebmeier dynamic nature (Kahl et al. 2015; Rasmussen et al. 2018b; Ruth et al. 2013; Pritchard et al. 2018). New seismic methods have been et al. 2018; Albert et al. 2019). Effort has gone into compiling developed, including shear-wave splitting analysis (Roman and large databases of magma storage depth estimates (Chaussard Gardine 2013) and novel receiver function techniques (Janiszewski and Amelung 2014), which most commonly identify storage et al. 2020). Electrical conductivity methods have seen significant regions between 2 and 8 km depth (Fig. 2; Rasmussen et al., 2019). advancements (Laumonier et al. 2017). Geochemical tools for studying magma depth have also improved substantially. Perhaps the greatest advancement has been in the field of melt inclusions, with new methods to account for vapor bubble growth (Hartley et 65Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

A0 Fs Sg n = 23 B 0 Sh (shallow) 5 5 Ok Sg 10 Depth (km) Fs 15 (deep) Cl Mk 10 Wd WatAerksaturation 15 n = 97 20 1 2 3 4 5 6 7 8 200 10 20 30 H2O (wt.%) Count Figure 2. Comparison of magma storage depth and magmatic water content (Rasmussen et al., 2019). A) Scatterplot showing the relationship between magma storage depth and magmatic water content for arc volcanoes with good constraints on both (n = 23). The colored symbols indicate data for volcanoes in the central-eastern Aleutians, a GeoPRISMS focus site, volcanoes and black/gray markers show data for other arc volcanoes. Magma storage depths are estimates derived from geophysical approaches, compiled by Rasmussen et al. (2019). Some volcanoes have multiple regions of storage that have been identified, and in those cases, the storage region that occurs on the water saturation curve is shown with a dark- colored marker and the other is shown with a light-colored marker. Magmatic water contents are the maximum water contents measured in melt inclusions from each volcano. The water saturation curve was calculated using VolatileCalc (Newman and Lowenstern 2002), and pressure was converted to depth using the crustal density model in Rasmussen et al. (2020). These results indicate a sweet spot for the storage of arc magmas between 2 and 8 km depth. The positive correlation between magma storage depth and magmatic water content, and the close association of both with the water saturation curve, are consistent with water as a primary control of magma storage depth (Rasmussen et al., 2019). The central- eastern volcanoes include Fisher (Fs), Shishaldin (Sh), Okmok (Ok), Seguam (Sg), Cleveland (Cl), Makushin (Mk), and Westdahl (Wd). B) Histogram of magma storage depths compiled for arcs globally (n = 97). Magma storage depths in less evolved (basalt-andesite) systems The basic principle of these tools is that chemical or physical are closely linked to magmatic water content, consistent with perturbations to a magmatic system may result in disequilibrium magmatic water content influencing magma storage depth (Fig. 2; between the phases (e.g., melt, crystals) and initiate diffusion. Upon Zellmer et al. 2016; Rasmussen et al. 2019). Despite recent progress, eruption, partially equilibrated crystals and melt erupt, freezing several questions remain. The most significant progress will come their chemical compositions in place. The extent of elibration can be from multidisciplinary studies, which often lead to improved determined by measuring the chemical composition, and through understanding of not only depth but also process. diffusion modeling, the time between the initial perturbation and the Over the last several years, there has been a paradigm shift in our eruption can be determined. Often, this tool is used in conjunction understanding of magmatic plumbing systems. Gone are images of with constraints from geophysics (Kahl et al., 2015; Rasmussen et singular melt-rich pools in the mid- to upper-crust. Evidence for al., 2018), geobarometry (Rasmussen et al., 2018; Ruth et al., 2018), magma storage in crystal-rich mush zones is ubiquitous (Bachmann and radiometric age dating (Cooper and Kent, 2014). and Bergantz 2008; Marsh 2015), and such reservoirs are exemplified in some volcanoes in GeoPRISMS focus areas e.g., (Grant et al. It is likely that primitive magmas erupted at the surface are biased 2019). Now, magmatic systems are commonly viewed with trans- towards shorter crustal transit times than more evolved magmas. crustal perspective in which mantle-derived magmas are processed Such magmas are commonly erupted at monogenetic cinder cones in vertically extensive, low-melt fraction mush networks (Cashman (Ruscitto et al. 2010; Salas et al. 2017; Rasmussen et al. 2018a; Pitcher et al. 2017). At some volcanoes, deep crustal seismicity has been and Kent 2019; Walowski et al. 2019). Thermo-chemical modeling linked to volcanic activity, demonstrating connectivity of magmatic has been used to argue that the preservation of high-forsterite plumbing systems (Power et al. 2004; Nichols et al. 2011). olivine in basaltic magma requires rapid transport through the crust (Ruprecht and Plank, 2013), which may facilitate eruptions of high- How long does it take for magma to transit the crust? forsterite olivines at cinder cones (Ruscitto et al. 2010; Salas et al. 2017; Walowski et al. 2019). Indeed, heightened seismicity occurs A long-standing challenge has been determining the time required over timescales of weeks to years before eruptions of monogenetic for magma to transit the crust. Recent advancements, particularly in cones, consistent with results from crystal clocks, suggesting the field of geochemistry, enable us to address this question. In the relatively short crustal residence times for these magmas (Albert et last decade, improved analytical methods and experimental data have al. 2016). Magmas that feed monogenetic cones in the Cascades are unlocked the potential of crystal clocks, or diffusion chronometers a current topic of study (Couperthwaite et al., 2020). (Costa and Morgan 2011; Costa et al. 2020). 66 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

Relatively primitive magmas are also be erupted from some longer- What are the timescales of lived edifices (Andrys et al. 2018). Short crustal transit times have volcanic unrest and eruption? also been found at these locations. Recent applications of diffusion chronometry to the crystal cargo of primitive magmas have Volcanic eruptions are often preceded by signs of unrest (Newhall et addressed this question: Ni zonation patterns found in the cores of al. 2017) such as increased seismicity (Roman et al. 2006; Passarelli mantle-equilibrated olivine from Volcán Irazú in Costa Rica indicate and Brodsky 2012), edifice inflation (Wnuk and Wauthier 2017; mantle-derived melts can transit the crust in timescales of months Pritchard et al. 2018), and changes in the composition and/or flux to years (Ruprecht and Plank 2013), and even faster timescales of of volatile emissions (de Moor et al. 2016). In an ideal world, these days have been found for the transit of magma from the Moho to the signals of unrest could be used to predict the timing and size of surface at Iceland (Mutch et al. 2019). Such timescales are similar to volcanic eruptions; however, there are many challenges to this those of unrest and eruption (Passarelli and Brodsky, 2012), raising approach: Some volcanoes erupt with little-to-no warning (Fee et the possibility that magma supplied from the mantle can directly feed al. 2017a), while other volcanoes exhibit signs of unrest that are not eruptions in some cases. We note that such short timescales (days followed by an eruption (Moran et al. 2011; Werner et al. 2011). to years) commonly determined for mafic systems may not tell the Additionally, the timescale of volcanic unrest preceding an eruption complete story. There is evidence that the residence time for crystals varies from volcano to volcano (Passarelli and Brodsky 2012), and mobilized in basaltic eruptions may be significantly longer than the (in some cases) from eruption to eruption at the same edifice (Roult mobilization timescales (de Maisonneuve et al. 2016). et al. 2012). With the compilation of large databases that document Evolved magmas erupted at long-lived edifices are likely subjected to geophysical and geochemical records of volcanic unrest (Newhall much longer periods of stalling and processing. Combined studies of et al. 2017), and the development of machine-learning techniques absolute crystal ages, determined radiometrically, and relative crystal for automating the interpretation of such datasets (Malfante et al. ages, determined with diffusion-based approaches, indicate that 2018), we are poised to make great progress in our understanding of crystal storage at long-repose interval volcanoes can last thousands the processes and timescales of magmatic processes that occurring to tens of thousands of years, but temperatures are above the solidus during the run-up to volcanic eruptions. A fundamental challenge for only a small fraction of this time (Cooper and Kent 2014). At is that the number of well-monitored eruptions we have is relatively Taupo Volcanic Center, plagioclase crystallization ages are similar to small and the monitoring record is restricted to only the most recent maximum ages implied by diffusion chronometers, consistent with eruptions. Petrologic approaches open up the possibility of studying relatively long-term storage under warmer conditions (Schlieder et geochemical signals of volcanic unrest throughout the entire rock al. 2019). An alternative tool for understanding storage timescales, record, thereby massively expanding the geographical and temporal which is also based on chemical diffusion, is the analysis of melt range of eruptions that can be studied. The extension of such studies inclusion morphology, which has been used to suggest timescales to present-day eruptions at well-monitored volcanoes allows for of tens to hundreds of years for the final assembly of large silicic a powerful interdisciplinary approach that combines geophysical magma bodies (Pamukcu et al., 2015). A relationship between ‘foresight’ with a mechanistic, petrologic context. magma composition and storage timescales is supported by the observation that volcanoes that erupt intermediate to evolved magma One of the key areas of interest in the last several years has been the compositions generally have longer periods of repose than volcanoes identification and study of magma recharge events (i.e., influxes of erupting relatively primitive magmas (Passarelli and Brodsky, 2012). new magma to a shallow magma storage region), which are thought to be common eruption triggers (Martin et al. 2008). Figure 3. Summary of crustal transport timescales. Crystal residence1 minute Iraz‘u Mantle replenishment 1 hour Iceland 10-4 10-3 10-2 1 day 1 month Eruption run-up 1 year Petrologic Seismic 10 ky Ma c Felsic Intermediate Ma c Felsic Intermediate E usive Magma ascent Explosive Eruption duration 10-1 100 101 102 103 104 105 106 107 108 Time (days) 67Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

104 Repose time (days) 103 1 year 102 101 1 hour 100 1 hour Basalt Basalt 10-1 Bas. And. Bas. And. 10-2 Andesite Andesite Dacite Dacite Rhyolite Rhyolite 10-3 101 102 103 104 105 106 107 108 109 Repose time (days) Figure 4. Run-up vs. repose. Modified after Passarelli and Brodsky (2012). The crystal clocks described above have been adapted for the study Another application of short-timescale diffusion chronometry is the of relatively short-timescale processes such as magma recharge; e.g., use of MgO zonation in olivine-hosted melt inclusions to determine Lynn et al. (2018) demonstrated that zonation of Li in olivine may syneruptive cooling rates (Newcombe et al. 2014; Saper and Stolper record magma recharge events that precede eruption by hours to 2020; Newcombe et al. 2020). When paired with the magma days. Fe-Mg zonation in olivine (Lynn et al. 2017; Rasmussen et al. decompression chronometers described above, this technique can 2018b) can preserve evidence of multiple magma recharge events. be used to constrain syneruptive pressure-temperature-time paths When combined with the geophysical record of volcanic unrest, the of mafic magmas; results of this approach suggest that rapidly- petrologic record of magma recharge can provide a posteriori context ascending gas-bearing magmas experience slower cooling during that may aid the interpretation of future geophysical monitoring ascent and eruption than slowly-ascending magmas (Newcombe signals (Rasmussen et al. 2018b). Interdisciplinary studies that et al. 2020). Conduit models indicate that temperature changes of combine geophysical and geochemical records of volcanic unrest are magma during syneruptive ascent exert a strong influence on ascent vitally important for improving the accuracy of eruption forecasting. dynamics and eruptive style (Gonnermann and Manga 2007; La Additionally, we lack a general understanding of what controls the Spina et al. 2015). Future efforts to integrate the petrologic record duration of run-up. Passarelli and Brodsky (2012) demonstrate that of conduit conditions into fluid dynamical models of magma ascent there is a broad correlation between run-up and repose (Fig. 4), yet and eruption will be required to advance our understanding of the the reason for this correlation remains puzzling. controls on eruptive style. Advancements in geospeedometers tuned to operate on even shorter timescales of seconds to hours have opened the door for research into Looking forward syn-eruptive processes. Decompression-driven ascent of magma in volcanic conduits is accompanied by exsolution of volatile species This article has followed the journey of mantle-derived melts from such as water and carbon dioxide (Fig. 5A), and the imprint of this their generation to eruption. Understanding this journey, and magma degassing is preserved as volatile concentration gradients its importance for controlling the life cycles of volcanoes across in quenched silicate melt and crystals (Fig.  5C). Modeling of the globe, is widely recognized as one of the grand challenges of syn-eruptive volatile diffusion during magma decompression volcano science (e.g., Volcanic Eruptions and Their Repose, Unrest, supports a relationship between decompression rate and eruptive Precursors, and Timing “ERUPT” report of the National Academies, style in basaltic systems, with rapidly decompressing magmas 2017). The GeoPRISMS community has studied every aspect of exhibiting higher mass eruption rates and vice versa (Chen et al. this journey, revealing a great deal about the nature of magma 2013; Lloyd et al. 2014; Ferguson et al. 2016; Barth et al. 2019; storage regions and the timescales of magma migration through the Newcombe et al. 2020). In rhyolitic systems, similar techniques crust. The insights gleaned from GeoPRISMS work and the strong have been used to study the onset and evolution of caldera-forming interdisciplinary community that we have forged will serve us well eruptions (Myers et al. 2016; Myers et al. 2018). ■as we build new initiatives to answer the many remaining mysteries of volcanology. 68 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

A H2O in melt (wt%) B Time (min) C Seguam-ol1 00 24 00 100 SIMS data 200 200 along ‘a’ 174 min 400 30 116 min 200 87 min Pressure (MPa) 20 Pressure (MPa) 10 Water (ppm) 400 0 -1000 0 1000 Radial distance (μm) Figure 5. Application of the water-in-olivine magma decompression chronometer to an olivine phenocryst from Seguam volcano (Vona et al. 2011; Shea and Hammer 2013; La Spina et al. 2015). A) Basaltic magma containing ~4 wt% water degasses during magma ascent and decompression. Colored circles correspond to model snapshots plotted in C. B) The water-in-olivine assumes a constant magma decompression rate (dP/dt), which is varied in order to find the best fit to measured water concentration gradients in olivine phenocrysts. C) Water concentration data measured along the crystallographic ‘a’ direction of a Seguam olivine phenocryst (black circles) is well matched by the model curve (in red) with a constant decompression rate of 0.035 MPa/s. Blue curves represent snapshots of the modeled decompression history indicated by the colored circles in A and B. References Aiuppa A., A. Bertagnini, N. Métrich, R. Moretti, A. Di Muro, M. Liuzzo, Crustal inheritance and a top-down control on arc magmatism at G. Tamburello (2010). A model of degassing for Stromboli volcano. Mount St Helens. Nat Geosci, 11, 11, 865-870 Earth Planet Sci Lett, 295, 1-2, 195-204 Bergantz G., J. Schleicher, A. Burgisser (2015). Open-system dynamics and mixing in magma mushes. Nat Geosci, 8, 10, 793-796 Aiuppa A., C. Federico, G. Giudice, S. Gurrieri (2005). Chemical mapping Blundy J., J. Mavrogenes B. Tattitch, S. Sparks, A. Gilmer (2015). Generation of a fumarolic field: La Fossa Crater, Vulcano Island (Aeolian Islands, of porphyry copper deposits by gas–brine reaction in volcanic arcs. Italy). Geophys Res Lett, 32, 13, doi:10.1029/2005gl023207 Nat Geosci, 8, 3, 235-240 Cai Y., M. Rioux, P.B. Kelemen, S.L. Goldstein, L. Bolge, A.R. Kylander- Aiuppa A., T.P. Fischer, T. Plank, P. Bani (2019). CO2 flux emissions from Clark (2015). Distinctly different parental magmas for calc-alkaline the Earth’s most actively degassing volcanoes, 2005–2015. Scientific plutons and tholeiitic lavas in the central and eastern Aleutian arc. Reports, 9, 1, 5442, doi:10.1038/s41598-019-41901-y Earth Planet Sci Lett, 431, 119-126 Cameron C.E., S.G. Prejean, M.L. Coombs, K.L. Wallace, J.A. Power, D.C. Albert H., F. Costa, A. Di Muro, J. Herrin, N. Métrich, E. Deloule (2019). Roman (2018). Alaska Volcano Observatory Alert and Forecasting Magma interactions, crystal mush formation, timescales, and unrest Timeliness: 1989–2017. Frontiers in Earth Science, 6, 86, doi:10.3389/ during caldera collapse and lateral eruption at ocean island basaltic feart.2018.00086 volcanoes (Piton de la Fournaise, La Réunion). Earth Planet Sci Lett, Cashman K.V., R.S.J. Sparks, J.D. Blundy (2017). Vertically extensive and 515, 187-199 unstable magmatic systems: A unified view of igneous processes. Science, 355, 6331, eaag3055 Albert H., F. Costa, J. Martí (2016). Years to weeks of seismic unrest and Chaussard E., F. Amelung (2014). Regional controls on magma ascent and magmatic intrusions precede monogenetic eruptions. Geology, 44, storage in volcanic arcs. Geochem Geophys, 15, 4, 1407-1418 3, 211-214 Chen Y., A. Provost, P. Schiano, N. Cluzel (2013). Magma ascent rate and initial water concentration inferred from diffusive water loss from Anantrasirichai N., J. Biggs, F. Albino, D. Bull (2019). A deep learning olivine-hosted melt inclusions. Contrib Mineral Petrol, 165, 3, 525- approach to detecting volcano deformation from satellite imagery 541, doi:10.1007/s00410-012-0821-x using synthetic datasets. Remote Sensing of Environment, 230, Cooper K.M., A.J. Kent (2014). Rapid remobilization of magmatic crystals 111179 kept in cold storage. Nature, 506, 7489, 480-483 Couperthwaite F., A. Kent, P. Wallace, C. Till (2020). An initial evaluation Andrys J., K.A. Kelley, E. Cottrell, M.L. Coombs (2018). Volatile contents of olivine diffusion timescales from monogenetic-style volcanoes in of western Aleutian magmas and their relationship to slab thermal the Oregon High Cascades. In: AGU 2020 Fall Meeting structure. In: AGU Fall Meeting Abstracts Costa F., D. Morgan (2011). Time constraints from chemical equilibration in magmatic crystals. Timescales of magmatic processes: from core Annen C., J. Blundy, R. Sparks (2006). The genesis of intermediate and to atmosphere. Wiley, Chichester, 125-159 silicic magmas in deep crustal hot zones. J Petrol, 47, 3, 505-539 Costa F., T. Shea, T. Ubide (2020). Diffusion chronometry and the timescales Bachmann O., G. Bergantz (2008). The magma reservoirs that feed supereruptions. Elements, 4, 1, 17-21 Barth A., M.E. Newcombe, T. Plank, H. Gonnermann, S. Hajimirza, G.J. Soto, A. Saballos, E. Hauri (2019). Magma decompression rate correlates with explosivity at basaltic volcanoes - Constraints from water diffusion in olivine. J Volcanol Geotherm Res, 387 Bedrosian P.A, J.R. Peacock, E. Bowles-Martinez, A. Schultz, G.J. Hill (2018). 69Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

of magmatic processes. Nat Rev Earth & Environment,1-14 earthquake flat and Rotoiti subsurface relationship (Taupo Volcanic Crosbie K.J., G.A. Abers, M.E. Mann, H.A. Janiszewski, K.C. Creager, C.W. Zone, New Zealand): A cryptic connection at depth? AGU Fall Meeting 2019, abstract V51F-0121 Ulberg, S.C. Moran (2019). Shear Velocity Structure From Ambient Hansen S., B. Schmandt, A. Levander, E. Kiser, J. Vidale, G. Abers, K. Noise and Teleseismic Surface Wave Tomography in the Cascades Creager (2016). Seismic evidence for a cold serpentinized mantle Around Mount St. Helens. J Geophys Res: Solid Earth, 124, 8, 8358- wedge beneath Mount St Helens. Nature Communi, 7, 1, 1-6 8375, doi:10.1029/2019jb017836 Hansen S.M., B. Schmandt (2015). Automated detection and location of de Maisonneuve C.B., F. Costa, C. Huber, P. Vonlanthen, O. Bachmann, microseismicity at Mount St. Helens with a large-N geophone array. M.A. Dungan (2016). How do olivines record magmatic events? Geophys Res Lett, 42, 18, 7390-7397, doi:10.1002/2015gl064848 Insights from major and trace element zoning. Contrib Mineral Harmon L.J., G.A. Gualda, D. Gravley, C.D. Deering (2019) Oscillating Petrol, 171, 6, 56 Storage: The conditions and sequence of magma storage and de Moor J.M., A. Aiuppa, J. Pacheco, G. Avard, C. Kern, M. Liuzzo, M. eruption through the Protracted Whakamaru Supereruption, Taupo Martínez, G. Giudice, T.P. Fischer (2016). Short-period volcanic Volcanic Zone, New Zealand. AGUFM 2019:V14A-02 gas precursors to phreatic eruptions: Insights from Poás Volcano, Hart L., N.L. Bennington, F. Lanza, S.W. Roecker, M.M. Haney, C.H. Thurber, Costa Rica. Earth Planet Sci Lett, 442, 218-227, doi.org/10.1016/j. K. Key (2018). High resolution imaging of the P-and S-wave velocity epsl.2016.02.056 structure at Okmok Volcano, Alaska. In: AGU Fall Meeting Abstracts DeBari S.M., A.R. Greene (2011). Vertical stratification of composition, Hartley M.E., J. Maclennan, M. Edmonds, T. Thordarson (2014). density, and inferred magmatic processes in exposed arc crustal Reconstructing the deep CO2 degassing behaviour of large sections. In: Arc-continent collision. Springer, 121-144 basaltic fissure eruptions. Earth Planet Sci Lett, 393, 120-131, doi. DeGrandpre K., H. Le Mével (2019). Finite element, multiphysics eruption org/10.1016/j.epsl.2014.02.031 model: Okmok 2008 eruption characterized from InSAR, GPS, Hildreth W., S. Moorbath (1988). Crustal contributions to arc magmatism seismic, and petrologic constraints. AGU Fall Meeting 2019, abstract in the Andes of central Chile. Contrib Mineral Petrol, 98, 4, 455-489 G31A-06 Huber C., M. Townsend, W. Degruyter, O. Bachmann (2019). Optimal DeGrandpre K., T. Wang, Z. Lu, J.T. Freymueller (2017). Episodic inflation depth of subvolcanic magma chamber growth controlled by volatiles and complex surface deformation of Akutan volcano, Alaska revealed and crust rheology. Nat Geosci, 12, 9, 762-768, doi:10.1038/s41561- from GPS time-series. J Volcanol Geotherm Res, 347, 337-359 019-0415-6 Degruyter W., C. Huber (2014). A model for eruption frequency of upper Husen A., R.R. Almeev, F. Holtz (2016). The effect of H2O and pressure crustal silicic magma chambers. Earth Planet Sci Lett, 403, 117-130 on multiple saturation and liquid lines of descent in basalt from the Delph J.R., K.M. Ward, G. Zandt, M.N. Ducea, S.L. Beck (2017). Imaging Shatsky Rise. J Petrol, 57, 2, 309-344 a magma plumbing system from MASH zone to magma reservoir. Janiszewski H.A., G.A. Abers, D.J. Shillington, J.A. Calkins (2013). Crustal Earth Planet Sci Lett, 457, 313-324 structure along the Aleutian island arc: New insights from receiver Ducea M.N., G.W. Bergantz, J.L. Crowley, J. Otamendi (2017). Ultrafast functions constrained by active-source data. Geochem Geophys, 14, magmatic buildup and diversification to produce continental crust 8, 2977-2992, doi:10.1002/ggge.20211 during subduction. Geology, 45, 3, 235-238 Janiszewski H.A., L.S. Wagner, D.C. Roman (2020). Aseismic mid-crustal Ebmeier S., J. Biggs, T. Mather, F. Amelung (2013). On the lack of InSAR magma reservoir at Cleveland Volcano imaged through novel observations of magmatic deformation at Central American receiver function analyses. Scientific Reports, 10, 1, 1-9 volcanoes. J Geophys Res: Solid Earth, 118, 5, 2571-2585 Jiang C., B. Schmandt, J. Farrell, F.-C. Lin, K.M. Ward (2018). Seismically Ebmeier S., J. Biggs, M. Poland, M. Pritchard, S. Zoffoli, M. Furtney, K. anisotropic magma reservoirs underlying silicic calderas. Geology, Reath (2019). Satellite geodesy for volcano monitoring in the 46, 8, 727-730 Sentinel-1 and SAR constellation era. In: IGARSS 2019-2019 IEEE Jicha B.R., O. Jagoutz (2015). Magma production rates for intraoceanic International Geoscience and Remote Sensing Symposium. IEEE, arcs. Elements, 11, 2, 105-111 5465-5467 Jicha B.R., D.W. Scholl, B.S. Singer, G.M. Yogodzinski, S.M. Kay (2006). Fee D., M.M. Haney, R.S. Matoza, A.R. Van Eaton, P. Cervelli, D.J. Revised age of Aleutian Island Arc formation implies high rate of Schneider, A.M. Iezzi (2017a). Volcanic tremor and plume height magma production. Geology, 34, 8, 661-664 hysteresis from Pavlof Volcano, Alaska. Science, 355, 6320, 45-48, Kahl M., S. Chakraborty, M. Pompilio, F. Costa (2015) Constraints on the doi:10.1126/science.aah6108 nature and evolution of the magma plumbing system of Mt. Etna Fee D., P. Izbekov, K. Kim, A. Yokoo, T. Lopez, F. Prata, R. Kazahaya, H. volcano (1991–2008) from a combined thermodynamic and kinetic Nakamichi, M.M. Iguchi (2017b). Eruption mass estimation using modelling of the compositional record of minerals. J Petrol, 56, 10, infrasound waveform inversion and ash and gas measurements: 2025-2068 Evaluation at Sakurajima Volcano, Japan. Earth Planet Sci Lett, 480, Kay S.M., B.R. Jicha, G.L. Citron, R.W. Kay, A.K. Tibbetts, T.A. Rivera 42-52 (2019). The calc-alkaline Hidden Bay and Kagalaska plutons and the Ferguson D.J., H.M. Gonnermann, P. Ruprecht, T. Plank, E.H. Hauri, B.F. construction of the central Aleutian oceanic arc crust. J Petrol, 60, Houghton, D.A. Swanson (2016). Magma decompression rates 2, 393-439 during explosive eruptions of Kīlauea volcano, Hawaii, recorded by Kelemen P.B., C.E. Manning (2015). Reevaluating carbon fluxes in melt embayments. Bull Volcanol, 78, 10, 71 subduction zones, what goes down, mostly comes up. Proceedings Fischer T.P., S. Arellano, S. Carn, A. Aiuppa, B. Galle, P. Allard, T. Lopez, of the National Academy of Sciences, 112, 30, E3997-E4006 H. Shinohara, P. Kelly, C. Werner, C. Cardellini, G. Chiodini (2019). Kim K., D. Fee, A. Yokoo, J.M. Lees (2015). Acoustic source inversion to The emissions of CO2 and other volatiles from the world’s subaerial estimate volume flux from volcanic explosions. Geophys Res Lett, 42, volcanoes. Scientific Reports, 9, 1, 18716, doi:10.1038/s41598-019- 13, 5243-5249 54682-1 Kiser E., A. Levander, C. Zelt, B. Schmandt, S. Hansen (2019). Upper Glasgow M.E., B. Schmandt, S.M. Hansen (2018). Upper crustal low- crustal structure and magmatism in Southwest Washington: frequency seismicity at Mount St. Helens detected with a dense Vp, Vs, and Vp/Vs results from the iMUSH active-source seismic geophone array. J Volcanol Geotherm Res, 358, 329-341, doi. experiment. J Geophys Res: Solid Earth, 124, 7, 7067-7080, org/10.1016/j.jvolgeores.2018.06.006 doi:10.1029/2018jb016203 Gonnermann H.M., M. Manga (2007). The fluid mechanics inside Kiser E., I. Palomeras, A. Levander, C. Zelt, S. Harder, B. Schmandt, S. a volcano. Annual Review of Fluid Mechanics, 39, 1, 321-356, Hansen, K. Creager, C. Ulberg (2016). Magma reservoirs from the doi:10.1146/annurev.fluid.39.050905.110207 upper crust to the Moho inferred from high-resolution Vp and Vs Gottsmann J., J. Biggs, R. Lloyd, Y. Biranhu, E. Lewi (2020). Ductility and models beneath Mount St. Helens, Washington State, USA. Geology, compressibility accommodate high magma flux beneath a silicic 44, 6, 411-414 continental rift caldera: Insights from Corbetti caldera (Ethiopia). La Spina G., M. Burton, M. de' Michieli Vitturi (2015). Temperature Geochem Geophys, 21, 4 evolution during magma ascent in basaltic effusive eruptions: A Grant E., K.M. Cooper, A. Kent, C.D. Deering, D. Gravley (2019). The 70 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

numerical application to Stromboli volcano. Earth Planet Sci Lett, doi:10.1007/s00410-014-1030-6 426, 89-100, doi.org/10.1016/j.epsl.2015.06.015 Newcombe M.E., T. Plank, P.D. Asimow, A. Barth, E. Hauri (2020). Water- Laumonier M., F. Gaillard, D. Muir, J. Blundy, M. Unsworth (2017). Giant magmatic water reservoirs at mid-crustal depth inferred from in-olivine magma ascent chronometry: Every crystal is a clock. J electrical conductivity and the growth of the continental crust. Earth Volcanol Geotherm Res Planet Sci Lett, 457, 173-180 Newcombe M.E., T. Plank, Y. Zhang, M. Holycross, A. Barth, A.S. Lloyd, Le Voyer M., P.D. Asimow, J.L. Mosenfelder, Y. Guan, P.J. Wallace, P. Schiano, D.J. Ferguson, E. Hauri (2020). Magma Pressure-Temperature-time E.M. Stolper, J.M. Eiler (2014). Zonation of H2O and F concentrations paths during mafic explosive eruptions. Frontiers in Earth Science, around melt inclusions in olivines. J Petrol, doi:10.1093/petrology/ doi.org/10.3389/feart.2020.531911 egu003 Newhall C.G., F. Costa, A. Ratdomopurbo, D.Y. Venezky, C. Widiwijayanti, Lloyd A.S., P. Ruprecht, E.H. Hauri, W. Rose, H.M. Gonnermann, N.T.Z. Win, K. Tan, E. Fajiculay (2017). WOVOdat – An online, growing T. Plank (2014). NanoSIMS results from olivine-hosted melt library of worldwide volcanic unrest. J Volcanol Geotherm Res, 345, embayments: Magma ascent rate during explosive basaltic 184-199, doi.org/10.1016/j.jvolgeores.2017.08.003 eruptions. J Volcanol Geotherm Res, 283, 0, 1-18, doi.org/10.1016/j. Nichols M.L., S.D. Malone, S.C. Moran, W.A. Thelen, J.E. Vidale jvolgeores.2014.06.002 (2011). Deep long-period earthquakes beneath Washington and Lynn K.J., M.O. Garcia, T. Shea, F. Costa, D.A. Swanson (2017). Timescales Oregon volcanoes. J Volcanol Geotherm Res, 200 3, 116-128, doi. of mixing and storage for Keanakāko‘i Tephra magmas (1500–1820 org/10.1016/j.jvolgeores.2010.12.005 C.E.), Kīlauea Volcano, Hawai‘i. Contrib Mineral Petrol, 172, 9, 76. Passarelli L., E.E. Brodsky (2012). The correlation between run-up and doi:10.1007/s00410-017-1395-4 repose times of volcanic eruptions. Geophys J Int, 188, 3, 1025-1045 Lynn K.J., T. Shea, M.O. Garcia, F. Costa, M.D. Norman (2018). Lithium Pamucku et al., 2015 diffusion in olivine records magmatic priming of explosive basaltic Pitcher B.W., A.J. Kent (2019). Statistics and segmentation: Using Big eruptions. Earth Planet Sci Lett 500, 127-135, doi.org/10.1016/j. Data to assess Cascades Arc compositional variability. Geochim epsl.2018.08.002 Cosmochim Acta, 265, 443-467 Malfante M., M. Dalla Mura, J.-P. Métaxian, J.I. Mars, O. Macedo, A. Inza Poland M.P., A. Miklius, A. Jeff Sutton, C.R. Thornber (2012). A mantle- (2018). Machine learning for volcano-seismic signals: Challenges driven surge in magma supply to Kīlauea Volcano during 2003–2007. and perspectives. IEEE Signal Processing Magazine, 35, 2, 20-30 Nat Geosci, 5, 4, 295-300. doi:10.1038/ngeo1426 Mann D., J. Freymueller (2003). Volcanic and tectonic deformation on Power J., S. Stihler, R. White, S. Moran (2004). Observations of deep long- Unimak Island in the Aleutian Arc, Alaska. J Geophys Res: Solid Earth, period (DLP) seismic events beneath Aleutian arc volcanoes; 1989– 108, B2 2002. J Volcanol Geotherm Res, 138, 3-4, 243-266 Marsh B.D. (2015). Magma chambers. In: The encyclopedia of volcanoes. Power J.A., et al. (2020). Goals and development of the Alaska Volcano Elsevier, 185-201 Observatory Seismic Network and application to forecasting and Martin V.M., D.J. Morgan, D.A. Jerram, M.J. Caddick, D.J. Prior, J.P. Davidson detecting volcanic eruptions. Seismol Res Lett, 91, 2A, 647-659, (2008) Bang! Month-scale eruption triggering at Santorini Volcano. doi:10.1785/0220190216 Science, 321, 5893, 1178-1178, doi:10.1126/science.1159584 Pritchard M., J. Biggs, C. Wauthier, E. Sansosti, D.W. Arnold, F. Delgado, Miller D.J., N.L. Bennington, P. Bedrosian, M.M. Haney, K. Key, C.H. S. Ebmeier, S. Henderson, K. Stephens, C. Cooper (2018). Towards Thurber (2018). Constraining magma storage at Okmok Volcano via coordinated regional multi-satellite InSAR volcano observations: joint interpretation of the local velocity and resistivity structure. In: results from the Latin America pilot project. J Appl Volcanol, 7, 1, 5 AGU Fall Meeting Abstracts Putirka K.D. (2017). Down the crater: where magmas are stored and why Mironov N., M. Portnyagin, R. Botcharnikov, A. Gurenko, K. Hoernle, they erupt. Elements, 13, 1, 11-16 F. Holtz (2015). Quantification of the CO2 budget and H2O–CO2 Rasmussen D.J., T.A. Plank, D.C. Roman (2019). Magmatic water content systematics in subduction-zone magmas through the experimental controls magma storage depth. AGU Fall Meeting 2019, abstract hydration of melt inclusions in olivine at high H2O pressure. Earth V21A-06 Planet Sci Lett, 425,1-11 Rasmussen D.J., T.A. Plank, D.C. Roman, E. Hauri, H.A. Janiszewski, E. Lev, Moore L.R., E. Gazel, R. Tuohy, A.S. Lloyd, R. Esposito, M. Steele-MacInnis, K.P. Nicolaysen, P.E. Izbekov (2018a). How Slab Depth is Reflected in E.H. Hauri, P.J. Wallace, T. Plank, R.J. Bodnar (2015). Bubbles matter: Aleutian Arc Magmas. In: AGU Fall Meeting Abstracts An assessment of the contribution of vapor bubbles to melt inclusion Rasmussen D.J., T.A. Plank, D.C. Roman, J.A. Power, R.J. Bodnar, E.H. Hauri volatile budgets. Amer Miner, 100, 4, 806-823, doi:10.2138/am- (2018b). When does eruption run-up begin? Multidisciplinary insight 2015-5036 from the 1999 eruption of Shishaldin volcano. Earth Planet Sci Lett, Moran S.C., C. Newhall, D.C. Roman (2011). Failed magmatic eruptions: 486, 1-14 late-stage cessation of magma ascent. Bull Volcanol, 73, 2, 115-122 Rasmussen D.J., T.A. Plank, P.J. Wallace, M.E. Newcombe, J.B. Lowenstern Morris R.A., S.M. DeBari, C. Busby, S. Medynski, B.R. Jicha (2019). Building (2020). Vapor bubble growth in olivine-hosted melt inclusions. Amer arc crust: Plutonic to volcanic connections in an extensional oceanic Miner arc, the Southern Alisitos Arc, Baja California. J Petrol 60, 6, 1195- Reath K., M. Pritchard, J. Biggs, B. Andrews, S. Ebmeier, M. Bagnardi, T. 1228, doi:10.1093/petrology/egz029 Girona, P. Lundgren, T. Lopez, M. Poland (2019). Using conceptual Mutch E.J., J. Maclennan, O. Shorttle, M. Edmonds, J.F. Rudge (2019). models to relate multi‐parameter satellite data to sub‐surface Rapid transcrustal magma movement under Iceland. Nat Geosci, 12, volcanic processes in Latin America. Geochem Geophys 7, 569-574 Rocco N., A.J. Kent, K.M. Cooper, C.D. Deering, D. Gravley (2019). Myers M.L., P.J. Wallace, C.J. Wilson, J.M. Watkins, Y. Liu (2018). Ascent Investigating Crustal and Mantle Contributions using Pb and Sr rates of rhyolitic magma at the onset of three caldera-forming Isotopes in Okataina and Taupo Volcanic Centers, Taupo Volcanic eruptions. Min Soc Am, 103, 6, 952-965, doi.org/10.2138/am-2018- Zone, New Zealand. AGU Fall Meeting 2019. abstract V51H-0137 6225 Roman D., J. Neuberg, R. Luckett (2006). Assessing the likelihood of Myers M.L., P.J. Wallace, C.J.N. Wilson, B.K. Morter, E.J. Swallow (2016). volcanic eruption through analysis of volcanotectonic earthquake Prolonged ascent and episodic venting of discrete magma batches at fault–plane solutions. Earth Planet Sci Lett, 248, 1-2, 244-252 the onset of the Huckleberry Ridge supereruption, Yellowstone. Earth Roman D.C., K.V. Cashman (2018). Top-down precursory volcanic Planet Sci Lett, 451, 285-297, doi.org/10.1016/j.epsl.2016.07.023 seismicity: Implications for ‘stealth’magma ascent and long-term Neave D.A., K.D. Putirka (2017). A new clinopyroxene-liquid barometer, eruption forecasting. Frontiers in Earth Science, 6, 124 and implications for magma storage pressures under Icelandic rift Roman D.C., M.D. Gardine (2013). Seismological evidence for long-term zones. Amer Miner, 102, 4, 777-794 and rapidly accelerating magma pressurization preceding the 2009 Newcombe M.E., A. Fabbrizio, Y. Zhang, C. Ma, M. Le Voyer, Y. Guan, eruption of Redoubt Volcano, Alaska. Earth Planet Sci Lett, 371, 226- J.M. Eiler, A.E. Saal, E.M. Stolper (2014). Chemical zonation in 234 olivine-hosted melt inclusions. Contrib Mineral Petrol, 168, 1, 1-26, Rosen J. (2016). Crystal clocks. Science, 354, 6314, 822-825, DOI: 10.1126/ science.354.6314.822 71Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Roult G., A. Peltier, B. Taisne, T. Staudacher, V. Ferrazzini, A. Di Muro Ulberg C.W., K.C. Creager, S.C. Moran, G.A. Abers, W.A. Thelen, A. (2012). A new comprehensive classification of the Piton de la Levander, E. Kiser, B. Schmandt, S.M. Hansen, R.S. Crosson (2020). Fournaise activity spanning the 1985–2010 period. Search and Local source Vp and Vs tomography in the Mount St. Helens region analysis of short-term precursors from a broad-band seismological with the iMUSH broadband array. Geochem Geophys station. J Volcanol Geotherm Res, 241, 78-104 van Keken P.E., B.R. Hacker, E.M. Syracuse, G.A. Abers (2011). Subduction Rudnick R.L., S.L. Goldstein (1990). The Pb isotopic compositions of lower factory: 4. Depth‐dependent flux of H2O from subducting slabs crustal xenoliths and the evolution of lower crustal Pb. Earth Planet worldwide. J Geophys Res: Solid Earth, 116, B1 Sci Lett, 98, 2, 192-207 Vogt K., T.V. Gerya, A. Castro (2012). Crustal growth at active continental Ruprecht P., T. Plank (2013). Feeding andesitic eruptions with a high- margins: numerical modeling. Phys Earth Planet Inter, 192, 1-20 speed connection from the mantle. Nature, 500, 7460, 68-72 Vona A., C. Romano, D.B. Dingwell, D. Giordano (2011). The rheology Ruscitto D., P. Wallace, E. Johnson, A. Kent, I. Bindeman (2010). Volatile of crystal-bearing basaltic magmas from Stromboli and Etna. contents of mafic magmas from cinder cones in the Central Oregon Geochim Cosmochim Acta, 75, 11, 3214-3236, doi.org/10.1016/j. High Cascades: Implications for magma formation and mantle gca.2011.03.031 conditions in a hot arc. Earth Planet Sci Lett, 298, 1-2, 153-161 Walker Jr B.A., G.W. Bergantz, J.E. Otamendi, M.N. Ducea, E.A. Cristofolini Ruth D.C., F. Costa, C.B. de Maisonneuve, L. Franco, J.A. Cortés, E.S. Calder (2015). A MASH zone revealed: The mafic complex of the Sierra Valle (2018). Crystal and melt inclusion timescales reveal the evolution of Fértil. J Petrol, 56, 9, 1863-1896 magma migration before eruption. Nat Communi, 9, 1, 1-9 Wallace P.J., V.S. Kamenetsky, P. Cervantes (2015). Melt inclusion CO2 Salas P.A., O.M. Rabbia, L.B. Hernández, P. Ruprecht (2017). Mafic contents, pressures of olivine crystallization, and the problem of monogenetic vents at the Descabezado Grande volcanic field shrinkage bubbles. Amer Miner, 100, 4, 787-794, doi:10.2138/am- (35.5 S–70.8 W): The northernmost evidence of regional primitive 2015-5029 volcanism in the Southern Volcanic Zone of Chile. Int J Sci, 106, 3, 1107-1121 Walowski K., P. Wallace, K. Cashman, J. Marks, M. Clynne, P. Ruprecht (2019). Understanding melt evolution and eruption dynamics of the Saper L., E. Stolper (2020). Controlled cooling-rate experiments on olivine- 1666 CE eruption of Cinder Cone, Lassen Volcanic National Park, hosted melt inclusions: chemical diffusion and quantification of California: Insights from olivine-hosted melt inclusions. J Volcanol eruptive cooling-rates on Hawaii and Mars. Geochem Geophys, 21, Geotherm Res, 387, 106665 2, e2019GC008772, doi:10.1029/2019GC008772 Werner C., C. Kern, D. Coppola, J.J. Lyons, P.J. Kelly, K.L. Wallace, D.J. Saunders K., B. Buse, M.R. Kilburn, S. Kearns, J. Blundy (2014). Nanoscale Schneider, R.L. Wessels (2017). Magmatic degassing, lava dome characterisation of crystal zoning. Chem Geol, 364, 0, 20-32, doi. extrusion, and explosions from Mount Cleveland volcano, Alaska, org/10.1016/j.chemgeo.2013.11.019 2011–2015: Insight into the continuous nature of volcanic activity over multi-year timescales. J Volcanol Geotherm Res, 337, 98-110 Schlieder T., K.M. Cooper, A. Kent, C.D. Deering, D. Gravley (2019). Understanding the thermal and chemical state of a silicic magmatic Werner C., D.J. Rasmussen, T. Plank, P.J. Kelly, C. Kern, T. Lopez, J. system prior to caldera-forming eruptions: Taupo Volcanic Center, Gliss, J.A. Power, D.C. Roman, P. Izbekov, J. Lyons (2020). Linking New Zealand. AGU Fall Meeting 2019, abstract V51F-0125 Subsurface to Surface using Gas Emission and Melt Inclusion data at Mount Cleveland volcano, Alaska. Geochem Geophys, 21, 7, Shea T., J.E. Hammer (2013). Kinetics of cooling- and decompression- e2019GC008882, doi:10.1029/2019gc008882 induced crystallization in hydrous mafic-intermediate magmas. J Volcanol Geotherm Res, 260, 127-145, doi.org/10.1016/j. Werner C.A., M.P. Doukas, P.J. Kelly (2011). Gas emissions from failed and jvolgeores.2013.04.018 actual eruptions from Cook Inlet Volcanoes, Alaska, 1989–2006. Bull Volcanol, 73, 2, 155-173, doi:10.1007/s00445-011-0453-4 Shillington D.J., H.J. Van Avendonk, M.D. Behn, P.B. Kelemen, O. Jagoutz (2013). Constraints on the composition of the Aleutian arc lower Wilkinson J.J. (2013). Triggers for the formation of porphyry ore deposits crust from VP/VS. Geophys Res Lett, 40, 11, 2579-2584 in magmatic arcs. Nat Geosci, 6, 11, 917-925, doi:10.1038/ngeo1940 Shillington D.J., H.J.A. Van Avendonk, W.S. Holbrook, P.B. Kelemen, M.J. Wnuk K., C. Wauthier (2017). Surface deformation induced by magmatic Hornbach (2004). Composition and structure of the central Aleutian processes at Pacaya Volcano, Guatemala revealed by InSAR. island arc from arc-parallel wide-angle seismic data. Geochem J Volcanol Geotherm Res, 344, 197-211, doi.org/10.1016/j. Geophys, 5, 10, doi:10.1029/2004gc000715 jvolgeores.2017.06.024 Shinohara H. (2005). A new technique to estimate volcanic gas Yogodzinski G., P. Kelemen (2007). Trace elements in clinopyroxenes from composition: plume measurements with a portable multi-sensor Aleutian xenoliths: Implications for primitive subduction magmatism system. J Volcanol Geotherm Res, 143, 4, 319-333, doi.org/10.1016/j. in an island arc. Earth Planet Sci Lett, 256, 3-4, 617-632 jvolgeores.2004.12.004 Zajacz Z., J.H. Seo, P.A. Candela, P.M. Piccoli, C.A. Heinrich, M. Guillong Sides I., M. Edmonds, J. Maclennan, D. Swanson, B. Houghton (2014). (2010). Alkali metals control the release of gold from volatile-rich Eruption style at Kīlauea Volcano in Hawai ‘i linked to primary melt magmas. Earth Planet Sci Lett, 297, 1-2, 50-56 composition. Nat Geosci, 7, 6, 464-469 Zellmer G.F., M. Pistone, Y. Iizuka, B.J. Andrews, A. Gómez-Tuena, S.M. Stephens K., C. Wauthier (2018). Satellite geodesy captures offset magma Straub, E. Cottrell (2016). Petrogenesis of antecryst-bearing arc supply associated with lava lake appearance at Masaya volcano, basalts from the Trans-Mexican Volcanic Belt: Insights into along- Nicaragua. Geophys Res Lett, 45, 6, 2669-2678 arc variations in magma-mush ponding depths, H2O contents, and surface heat flux. Amer Miner, 101, 11, 2405-2422 Sun J., C. Wauthier, K. Stephens, M. Gervais, G. Cervone, P.C. La Femina, M. Higgins (2019). Deep learning application on volcanic deformation Zimmer M.M., T. Plank, E.H. Hauri, G.M. Yogodzinski, P. Stelling J. Larsen, detection and blind source separation in InSAR Data. AGU Fall B. Singer, B. Jicha, C. Mandeville, C.J. Nye (2010). The Role of Water Meeting 2019, G13C-0556 in Generating the Calc-alkaline Trend: New Volatile Data for Aleutian Magmas and a New Tholeiitic Index. J Petrol, 51, 12, 2411-2444, Syracuse E.M., G.A. Abers (2006). Global compilation of variations in slab doi:10.1093/petrology/egq062 depth beneath arc volcanoes and implications. Geochem Geophys, 7, 5 Till C.B., A.J.R. Kent, G.A. Abers, H.A. Janiszewski, J.B. Gaherty, B.W. Pitcher (2019). The causes of spatiotemporal variations in erupted fluxes and compositions along a volcanic arc. Nat Communi, 10, 1, 1350. doi:10.1038/s41467-019-09113-0 Turner S.J., C.H. Langmuir, R.F. Katz, M.A. Dungan, S. Escrig (2016). Parental arc magma compositions dominantly controlled by mantle- wedge thermal structure. Nat Geosci, 9, 10, 772-776 Ubide T., C.A. McKenna, D.M. Chew, B.S. Kamber (2015). High-resolution LA-ICP-MS trace element mapping of igneous minerals: In search of magma histories. Chem Geol, 409, 157-168 72 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

2019 From rifting to drifting: evidence from 2011 rifts and margins worldwide | AGU Fall Synthesis and Integration Theoretical Meeting, San Francisco, CA, Dec 13 EarthScope/GeoPRISMS Science & Experimental Institute | San Mini-Workshop on the Himalayan Workshop for Eastern North America Antonio, TX, Feb 26-Mar 1 Seismogenic Zone (HSZ) | AGU Fall | Bethlehem, PA, Oct 26-29 Data, Science, and Education & Meeting, San Francisco, CA, Dec 15 Alaska Primary Site Planning Outreach Legacy Products | AGU Fall Workshop | Portland, OR, Sep 22-24 Meeting, San Francisco, CA, Dec 8 2014 SCD Implementation Workshop Strategies for Synthesis, Integration, | Bastrop, TX, Jan 5-7 and Future Opportunities | AGU Fall Workshop to cultivate and coordinate GeoPRISMS Community Seismic Meeting, San Francisco, CA, Dec 8 GeoPRISMS studies of the Hikurangi Experiment along the ENAM subduction margin | AGU Fall Luncheon | AGU Fall Meeting, 2018 Meeting, San Francisco, CA, Dec 14 San Francisco, CA, Dec 8 Mini-Workshop for the South ExTerra: Understanding Convergent ExTerra: Evolution of arc crust | AGU Island, New Zealand Primary Site Margin Processes Through Studies Fall Meeting, Washington, DC, Dec 9 coordination | AGU Fall Meeting, of Exhumed Terranes | AGU Fall Investigating subduction processes San Francisco, CA, Dec 14 Meeting, San Francisco, CA, Dec 7 at the Hikurangi Margin, New Integrating CRISP IODP Drilling Zealand | AGU Fall Meeting, 2013 and 3D Seismic Study | AGU Fall Washington, DC, Dec 9 Meeting, San Francisco, CA, Dec 7 Planning Workshop for the New Using Geoinformatics Resources 2017 Zealand Primary Site | Wellington, to Explore the Generation of New Zealand, April 15-17 Convergent Margin Magmas | AGU Theoretical & Experimental Kermadec Arc-Havre Trough Fall Meeting, San Francisco, CA, Dec 4 Institute for the RIE Initiative | Planning Mini-workshop | AGU Fall EarthScope-GeoPRISMS Albuquerque, NM, Feb 8-10 Meeting, San Francisco, CA, Dec 8 Opportunities in Eastern North ENAM science advances: progress Workshop on Field Logistics America | Bastrop TX, May 20-21 and outlook | AGU Fall Meeting, for GeoPRISMS Research in the New Orleans, LA, Dec 10 Aleutian Arc | AGU Fall Meeting, 2010 Early-Career Scientists/Faculty: San Francisco, CA, Dec 8 Introduction to GeoPRISMS/ Exploring the interplay between solid RIE Implementation Workshop MARGINS Data Resources, Mini- Earth tectonics and surface processes | Santa Fe, NM, Nov 4-6 Lessons, and Effective Broader using community codes | AGU Fall MARGINS Successor Program Impacts | AGU Fall Meeting, Meeting, San Francisco, CA, Dec 11 Planning Meeting | San New Orleans, LA, Dec 10 Collaborative Efforts in the East Antonio, TX, Feb 15-17 Amphibious community experiments in African Rift System | AGU Fall Alaska and related opportunities | AGU Meeting, San Francisco, CA, Dec 12 GeoPRISMS Fall Meeting, New Orleans, LA, Dec 10 Meetings & 2012 Workshops 2016 Planning Workshop for the East African EarthScope-type Canadian Cordillera Rift System | Morristown, NJ Oct 25-27 Seismic Array and GPS Network | AGU GeoPRISMS/EarthScope Planning Fall Meeting, San Francisco, CA, Dec 11 Workshop for the Cascadia Primary Volcanoes in Extensional and Site | Portland, OR, Apr 5-6 Compressional Settings | AGU Fall IODP Opportunities for SCD | AGU Meeting, San Francisco, CA, Dec 11 Fall Meeting, San Francisco, CA, Dec 6 Early Career Investigators 2015 Networking Luncheon | AGU Fall Meeting, San Francisco, CA, Dec 4 Theoretical & Experimental Marine Geophysics in the Cascadia Institute for the SCD Initiative | Primary Site | AGU Fall Meeting, Redondo Beach, CA, Oct 11-15 San Francisco, CA, Dec 2 73Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

74 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

program highlights GeoPRISMS unique elements enabling fundamental advances 76 Perspectives from the National Science Foundation 78 Reflections from the GeoPRISMS former program Chairs 80 The Distinguished Lectureship Program: Raising Geoscience awareness 82 Supporting and training the next generation of Geoscientists 92 Pairing community seismic experiments with seismic community development 96 The GeoPRISMS data portal: Community support through data access 75Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Program Highlights Perspectives from the National Science Foundation Jennifer Wade (Program Director, National Science Foundation) My path to writing this letter started way back in the early have not only embraced that, but enabled it. I am also proud of the days of the predecessor program, MARGINS. I was a collaborative relationships that have developed internally at NSF. fresh faced graduate student, drawn into weeks of field Managing a program at the boundary between Earth and Ocean work tacked onto a workshop in Heredia, Costa Rica. It was 2001, Sciences requires good communication, mutual respect, and trust and this was my introduction to the Subduction Factory. More - all of which we in EAR have with Debbie Smith, Candace Major, importantly, it was my introduction to a community of scientists and others in OCE with whom we have partnered in this program. committed to multidisciplinary shoreline-crossing research, and I The team at NSF that developed from GeoPRISMS continues to was hooked. work hard to promote cross-coastal research well into the future. Ten years later, I was one of a team of Program Directors at NSF NSF hasn't managed GeoPRISMS alone. Juli Morgan, Peter van managing the decadal program that followed: GeoPRISMS. I could Keken, and now especially Demian Saffer have been astounding spend my allotted space in this last newsletter highlighting the partners as Office Chairs. Each Chair has different styles, yet each incredible science that has been done, the discoveries made, and was perfect for whatever faced the program while they were at the accomplishments too long to list. But the most remarkable part helm. I am so grateful to them for that. It is not easy to be the liaison of the GeoPRISMS program is the people who do the science. For between an ambitious community of scientists and a federal agency, twenty years, this community has collaborated, argued, traveled the but these three made my job better. And while the office changed world, answered questions, and asked a hundred more. You have hands over the years, the one constant has been Anaïs Férot. None found ways to connect geochemistry to geodesy, you have found of what we read in this issue, or have experienced at a meeting, or commonality across tectonic settings, and developed new ways to see on the website would have been possible without her. Every collaborate with each other in the field, using tools across all kinds community should be so lucky as to have her driving it forward. of platforms. All of this you have done while supporting each other I hope you all see this as I do - not as the end of an era, but the and your students so well that this program is held up as an example start of something transformational. I am not the only MARGINS within NSF of what community science can be. kid who grew up to be involved in GeoPRISMS, and now that During MARINGS and GeoPRISMS, the programs have funded I'm nearly twenty years on from that first trip to Costa Rica I can over 300 awards, 30 workshops, and numerous postdocs. We have see with such clarity how learning to do science in a way that is directly supported over 1100 individuals, and the percentage of early inherently collaborative and cross-disciplinary leads to progress. The career principal investigators involved in these projects has increased community has built a foundation of scientific discovery and has fivefold. I am particularly proud of the engagement of early career researchers in this program, and of the way more senior scientists ■nurtured visionary scientists that will carry this spirit forward into everything that comes next, and I cannot wait to be a part of it. From left to right, top to bottom. Nodal seismometers installation in the crater of Mount St Helens, following the GeoPRISMS-funded iMUSH deployment in 2014. B. Students presenting their research at the AGU GeoPRISMS Townhall Meeting. C. Participants of the 2019 TEI for Synthesis & Integration in front of the Alamo in San Antonio, TX; D. Participants of the 2015 TEI for the SCD Initiative in California; E. Research Cruise participants preparing MT receiver for deployment during the 2015 GeoPRISMS-funded field campaign to the Aleutians; F. Program Director Jennifer Wade addressing the GeoPRISMS Community during the 2019 GeoPRISMS Theoretical & Experimental Institute. 76 • GeoPRISMS Newsletter Issue No. 43 Fall 2020 Photo by A. Férot Photo by B. Schmandt

Photo by A. Férot Photo by A. Férot Fall 2020 Issue No. 43 GeoPRISMS Newsletter • 77  Photo by A. Férot Photo by K. Key

Program Highlights Continental margins research through MARGINS and GeoPRISMS Juli Morgan, Geoff Abers, and Peter van Keken More than three decades ago, back in the last century, It started small, with modest deployments of onland seismometers an idea was hatched in a room full of great minds that combined with nearshore marine seismic sources, or comparisons of continental margins were the place where land people uplifted and deformed rocks in the mountains with muds collected and sea people could sit down together, and start to talk to each from the seafloor. But it became increasing clear to all, including other. This first meeting, held in 1988 in Irvine, CA, was close enough NSF, that the two parts of the world were closely connected, and to the shoreline that each group was near familiar territory. Up thus neither could be fully understood without consideration of the until that time, the National Science Foundation generally divided other. This realization came about largely through the involvement the world into two parts: one you could see from an airplane, on of graduate students and young scientists who were trained foot, or in a vehicle (NSF EAR), whereas the other required a boat, within these novel shoreline crossing investigations, and helped to submersible, or diving gear (NSF OCE). The scientists funded by develop new approaches to integrate such observations, and design these NSF divisions typically received grants to work in one place hypotheses to test. The MARGINS community gradually expanded or the other, but with some exceptions, generally didn’t have many to include a wider range of expertise: geophysicists, geochemists, opportunities to talk to each other. structural geologists, volcanologists, sedimentologists, as well as Remarkably, the fifty-seven men and eight women in attendance experimentalists, modelers, and so many more. Scientists and realized that, with enough mental fluidity and a well positioned graduate students came from around the world, gathering with gathering place, it was possible to bring these two worlds together their colleagues in attractive places, which moved progressively to discuss exciting scientific ideas, and the concept of the NSF to higher and higher elevations (Eugene, Mount Hood, Snowbird MARGINS Program was born. Over the following decade, more again). In these settings, participants discussed new ideas and new women joined the group, more meetings happened near beaches approaches, and presented cutting edge science emerging from (such as Avalon, Kona, La Jolla, Quinault, and, oddly, Snowbird) these collaborative, interdisciplinary, shoreline-crossing efforts. and the two groups gradually developed a common language, one The outcomes of these stimulating gatherings (Theoretical and that allowed terrestrial geoscientists to communicate with marine Experimental Institutes, TEIs) were enshrined in books destined geoscientists. In the process, they discovered that they were actually for shelves all over the world. studying the exact same things, and great science began to happen. The original National Academy report on a Margins research initiative, arising from the 1988 Irvine workshop Photo by A. Férot 78 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

MARGINS and GeoPRISMS meetings and workshops locations. The success of the MARGINS movement in advancing our As the GeoPRISMS Program comes to a close, after two decadal understanding of continental margins that cross the shoreline was programs that had their origins more than thirty years ago, we can acknowledged by the NSF MARGINS Decadal Review (2009). This look back on the significant achievements that have been made enabled a new movement called GeoPRISMS (i.e., Geodynamic possible by the active community efforts facilitated by the MARGINS Processes at RIfting and Subducting MarginS), which formalized and GeoPRISMS Offices, supported by direct funding from NSF the best attributes of the MARGINS effort while broadening the EAR&OCE to teams of researchers. We have seen the research community of scientists who participating in the movement. community diversify, become younger (academically speaking), Research programs coalesced in several new locations, including and much more engaged in interdisciplinary and international active and passive margins around the US (Alaska, Cascadia, Eastern research than we could have hoped for when the MARGINS ship North America), the East African Rift, and New Zealand, while started sailing. We have also seen major scientific advances enabled also enabling the synthesis and deeper comprehension of rifting by these programs, in our understanding of the fluid cycles and and subducting margins around the world. A key characteristic thermal structure of subduction zones, of the behavior and geologic of this movement continued to be attractive conference venues controls on great earthquakes, in the ways in which continents break where scientists could gather to exchange ideas, sometimes near apart, how magmas are produced in all of these settings, and many the shorelines (Portland, OR; Wellington, NZ; Morristown, NJ), other areas. We are happy to have been strongly involved at various but occasionally a bit farther inland on ancient or future continental margins (San Antonio and Bastrop, TX; Albuquerque, NM; ■stages of these programs and look forward to seeing a large number Bethlehem, PA). Importantly, each setting fostered collaborative discussions during which a broad community of investigators could of ongoing projects come to fruition in the coming years. define the key science questions that will drive continental margins investigations in the future, design integrative amphibious science investigations, and most essentially, share ideas and build a science community that could work effectively for decades to come. Photo by A. Férot 79Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Program Highlights The Distinguished Lectureship Program: Raising Geoscience awareness Anaïs Férot (GeoPRISMS Office, The Pennsylvania State University) GeoPRISMS has actively engaged in developing and maintaining \" In a decade, 226 institutions an Education & Outreach program geared towards the broader across the US and beyond hosted a science community and the general public. The well-established GeoPRISMS DLP Speaker GeoPRISMS Distinguished Lectureship Program (DLP) has played an instrumental role illustrating the depth and breadth of the GeoPRISMS Our students had never seen active program, disseminating new findings, and increasing global learning. seismic profiles. The data were beautiful, Starting in 2010, the DLP sponsored 10 lecture series centered around GeoPRISMS research topics. 36 scientists - half of them women - selected and relevant to the crustal cross- from a wide range of disciplines and career levels traveled across the United section of eastern North America that States and beyond to share the cutting edge science they conducted through students spend so much time thinking GeoPRISMS. The presentations offered by the speakers included standard academic seminars, guest lectures in Earth Sciences undergraduate and about in their upper-level course. graduate level courses, and public talks. The DLP has been extremely popular and received strong interest, with applications from over 500 US We like our students to be pushed to see institutions and abroad. From moderate-sized community and liberal new and different research, including arts colleges, to museums and public venues, 226 institutions hosted a things they do not understand, and this DLP Speaker and more than 10,000 people have attended these lectures. is exactly what Dr. Bécel's talk did. We GeoPRISMS DLP Speaker Anne Bécel at James Madison University, presented do not have a graduate program, so we new findings on the deep structure of the Eastern North American Margin and the implications for continental breakup and early seafloor spreading \"need talks like this to show them what other history. The lecture is available on the GeoPRISMS Youtube Channel. Photo credit: E. Johnson scientists from different institutions can do. 80 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

The lecture series was coordinated by the GeoPRISMS Office. Speakers alloted time to meet with the students to share their valuable Applications, usually announced in early summer, were opened to experience and answer questions regarding career and research any US college or university. Institutions that were not currently opportunities. The DLP lectureship has greatly stimulated students' involved with GeoPRISMS research were strongly encouraged to interest and infused a sense of possibilities in pursuing alternative apply, including those granting undergraduate or masters degrees, as paths in science. well as those with PhD programs. The office promoted the program and mailed the lecture brochure each year to over 600 Geoscience The DLP also improved the representation of women in STEM departments and science centers across the US. The information was - successful female scientists discussing their accomplishments also shared on social media and through the GeoPRISMS listserv and undeniably inspired female students and Early Career Investigators newsletter. The office provided logistical support and guidance to the to pursue education in geosciences. Additionally, the program hosts to ensure the program goals were achieved. Best practices were extended the reach and inclusiveness of GeoPRISMS science by codified and shared with hosts to properly advertise the speaker’s bringing high-caliber speakers to departments geographically visit, arrange local visits to public venues, provide enough flexibility isolated and/or with no or limited speaker series budget. DLP visits to accommodate the speaker’s schedule, and record the lectures for would often draw audiences from across campus and neighboring archival and dissemination - available recordings are compiled on institutions - sometimes from over 50-miles away. The DLP initiated the GeoPRISMS Youtube channel. The GeoPRISMS Office carefully new collaborations, strengthened networks, drew new avenues of prepared the Speakers’ itineraries based on their availability. Requests research and overall raised the level of academic discussion amongst from the hosts were also taken into consideration. Efforts were students, postdoctocs, and more established researchers. made to coordinate visits to neighboring institutions to make the most of the Speakers’ time and the budget allocated to the lecture A well-coordinated lecture series such as the DLP has offered a series. By doing so, the office managed to keep the acceptance rate diverse array of exciting and relevant geoscience topics. While the to about 40% despite budget limitations and subsequent reduction lecture series has successfully promoted the activities and products of the number of speakers (scaled down from 8 to 6 in 2015, then of the GeoPRISMS Program, the DLP also provided an excellent to 4 in 2016). Hosts were responsible for accommodation and local education opportunity for the public and college audience and raised expenses, GeoPRISMS supported the speakers’ travel expenses. the level of geoscience awareness. The GeoPRISMS Office thanks the As highlighted in feedback from the hosts and attendees, the benefits institutions for hosting a Speaker and for making the Distinguished of the DLP went beyond programmatic updates. The lecture series Lectureship Program such a success. The GeoPRISMS office is also offered outstanding opportunities for students to interact with grateful to the 36 researchers who have served as a GeoPRISMS experts and be exposed to new topical areas, steering them in new Distinguished Speaker - for taking time out of their busy schedules scientific directions. In conjunction with their lectures, the DLP ■to travel on behalf of GeoPRISMS, for sharing their work and their passion, and for inspiring a whole new generation of scientists. GeoPRISMS DLP Speakers from 2010 to 2019. 2010-2011 Emily Brodsky, Becky Dorsey, Chris Goldfinger, Katie Kelley, Rudy Slingerland, Paul Umhoefer, Peter van Keken 2011-2012 Geoff Abers, Steve Holbrook, Katie Keranen, Alison Shaw, John Swenson, Paul Umhoefer, Harm Van Avendonk, Peter van Keken 2012-2013 Geoff Abers, Magali Billen, Heather Deshon, Katie Keranen, Craig Manning, Tyrone Rooney, Chris Scholz, Harm Van Avendonk 2013-2014 Rebecca Bendick, Heather Deshon, Craig Manning, Jeff McGuire, Josh Roering, Tyrone Rooney, Chris Scholz, Kyle Straub 2014-2015 Richard Allen, Rebecca Bendick, Elizabeth Cottrell, Bradley Hacker, Andy Nyblade, Josh Roering, Robert Stern, Kyle Straub 2015-2016 Elizabeth Cottrell, Bradley Hacker, Beatrice Magnani, Andy Nyblade, Robert Stern, Laura Wallace 2016-2017 Esteban Gazel, Beatrice Magnani, Heather Savage, Brandon Schmandt 2017-2018 Esteban Gazel, Cindy Ebinger, Heather Savage, Brandon Schmandt 2018-2019 Jaime Barnes, Anne Bécel, Cindy Ebinger, Abhijit Ghosh 81Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Program Highlights GeoPRISMS Early Career engagement: Supporting and training the next generation of Geoscientists Anaïs Férot (GeoPRISMS Office, The Pennsylvania State University) One of the strongest and unique aspects of GeoPRISMS more confidence. Overall, the experience has been scientifically has been its constant support of Early Career Researchers stimulating and rewarding, as revealed by the positive feedback and their professional development through networking received from Early Careers who attended GeoPRISMS meetings. and leadership opportunities, as well as a wide range of experiential For some, their participation has led to new collaborations and and educational activities. Early Career Scientists - here defined scientific directions. Others have received mentorship and job as undergraduates, graduates, postdocs, assistant researchers, opportunities. For many, they went back home with a feeling their and pre-tenure faculty members - hold a central place within the opinion matters. program, and have been heavily involved in the planning process Student oral and poster competitions were organized each year at and engaged in research projects. Activities coordinated by the the AGU Fall Meeting by the GeoPRISMS Office to highlight the GeoPRISMS Office and centered around Early Career Researchers important role of student research in accomplishing GeoPRISMS- - with an emphasis on students and postdocs - have been key in related science goals and encourage cross-disciplinary input. The enhancing their engagement within the program, and expanded contest was open to all students working on topics closely related to the reach of the program and strengthened its community base. GeoPRISMS or MARGINS science objectives. A dedicated poster Meetings and workshops have been crucial in keeping the session was hosted at the GeoPRISMS AGU Townhall Meeting to community engaged and informed. In 10 years, these meetings have provide the entrants an additional chance to meet with the judges, gathered thousands of individuals from across the globe and a wide network with their peers, and receive feedback on their work. Since range of career levels and science perspectives, to discuss the progress 2010, over 200 students have entered the competition - among them, made on the science objectives and to disseminate emerging results. Building on the effort initiated by GeoPRISMS predecessor program ■20 have been awarded with a $500 cash prize for best oral or best MARGINS, Early Careers have been strongly encouraged to attend the program events, from small scale mini-workshops at AGU Fall poster presentation, and 40 have received honorable mentions. Meetings to large community events such as the implementation workshops for primary sites and Theoretical & Experimental Institutes (TEIs). Since 2010, approximately 300 students and postdocs have received participative support covering their airfare and local expenses to attend these meetings. GeoPRISMS has made sure their voices were heard: Early Career Investigators have been invited to lead breakout groups, to convene mini-workshops, and to give keynote lectures. They have participated in the development of the implementation plans for each primary site. Dedicated symposia organized prior to primary site implementation meetings and TEIs provided Early Careers a chance to learn about the program, the objectives of the meeting, and develop their network. For half a day, Early Career Symposium participants received background knowledge from more established researchers. Poster sessions and popup presentations allowed them to mingle with peers, present their work, and meet with NSF representatives, all in a friendly, less intimidating environment. On top of providing a sense of belonging, the symposia have allowed the students and postdocs to come fully prepared to subsequent meetings and engage in discussions with 82 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

2010-2019 Winners and Honorable Mentions of the GeoPRISMS Best oral and poster student presentation competition 83Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Since the beginning of the program, GeoPRISMS has sponsored course introducing topics in seismology and the tectonic history of 14 postdoctoral researchers in conducting up to two years of Alaska. The students then took part in a field trip that introduced multidisciplinary research at US institutions. The GeoPRISMS the geology of accretionary prisms. They finally joined PI Lindsay Postdoctoral scholarship, typically awarded to individuals within Worthington (UNM) in the recovery of 398 nodes in eastern Kodiak. five years of graduation, encourages them to solidify their skills, The experience offered by these programs are as numerous as they diversify their expertise, and establish peer relationships. All who are varied. Selected apply-to-sailors and field participants have completed their postdoc appointments have since moved into faculty been engaged in all aspects of on-board and field science activities, or research positions (read testimonials p. 86). from instrument preparation, deployment and recovery, to data Terrestrial field campaigns and marine cruises associated with acquisition and processing. Participants also communicated research GeoPRISMS-funded projects have provided additional opportunities efforts in real time via blogs, and contributed Reports from the Field for hands-on training. With help from the GeoPRISMS Office, published in the GeoPRISMS Newsletters, sharing the excitement collaborative research projects - involving large teams of investigators of field work and inspiring Early Career Scientists to take part in and long term data acquisition - have opened participation to the similar experiences. These initiatives have offered invaluable insights science community and educators via competitive Apply-to-Sail into conducting high-quality, collaborative, and interdisciplinary programs, calls for field participation, and invitations to attend science in the field. thematic short courses (see report from Principal Investigators Aubreya Adams and Maureen Long p.92). Calls to participate inthe 2010-2020 GeoPRISMS-funded Cascadia Initiative, the ENAM, and the Alaska & Aleutians Community Seismic Experiments have been extremely GeoPRISMS in numbers popular and led to a high number of applications for a very limited number of positions. For example, in June 2019, seven undergraduate 218 students, selected from a national pool of 54 applicants, participated in a short course in Kodiak, AK. Led by PI Aubreya Adams (Colgate PIs and Co-PIs U), this week-long experience immersed participants in an intensive 187 Fifty early career scientists attended the early career symposium organized ahead of the 2015 TEI for the SCD Initiative. This meeting Research Projects was the first in GeoPRISMS and MARGINS history to have more than 50% students, postdocs and pre-tenure scientists attending 35% the meeting and more than 40% female attendees. These numbers are in part due to the dedicated attention that GeoPRISMS has Female Investigators shown engaging early-career scientists. 45% Collaborative Projects 25% Interdisciplinary Projects 84 • GeoPRISMS Newsletter Issue No. 43 Fall 2020 Photo by A. Férot

Early Career Symposium Photo by A. Férot participants attending a pre-meeting field trip during the 2012 GeoPRISMS implementation workshop for the EARS Primary Site. These efforts are reflected by the current program demographics. A | Attendance for GeoPRISMS large meetings The number of undergraduates, graduates, and postdocs attending Students & postdocs GeoPRISMS meetings have increased over the years (fig. 1A). Since Other participants 2010, approximately 700 Early Career Researchers - representing nearly 30% of all meeting participants - have attended mini- 150 workshops at AGU Fall Meetings, implementation workshops for primary sites, and Theoretical & Experimental Institutes. 100 Subsequently, more Early Careers have been engaged in projects, as revealed by the increased number of early career investigators and 50 the number of undergraduate, graduates, and postdocs supported by GeoPRISMS-funded awards (fig.1B). Additionally, almost half 0 of GeoPRISMS Investigators are female (fig 1C.); GeoPRISMS investigators tend to be involved in projects that are collaborative 2021202202101C20111a012sAE11lcE0NaaSAsARdCkRIiaMSEDa NZ and interdisciplinary. TEI TEI Looking forward TEI As GeoPRISMS comes to completion after its run of more than 10 20152S0C13D years, time has come to consider its legacy and look ahead at the 2017 RIE work that still needs to be done to advance geoscience understanding 2019 S&I and further develop a diverse community of researchers. GeoPRISMS has successfully executed the vision of an B | Students & postdocs supported by GeoPRISMS GeoPRISMS interdisciplinary, shoreline-crossing science program and and MARGINS projects MARGINS demonstrated the importance of science driven by a community of researchers. The program effectively built and educated a broadly 200 interdisciplinary group of scientists, training the next generation of practitioners in a highly collaborative culture. As revealed by 150 Graduates Undergraduates current GeoPRISMS demographics, the program fostered a research 100 community balanced with respect to gender and career status.These numbers also reveal that there is still much work to be done within 50 the geosciences to address long-standing inequities and the lack 0 of representation and inclusivity. Research programs built upon GeoPRISMS's successful model should lead the way in developing Postdocs best practices to attract, train, and retain BIPOC (Black, Indigenous, and People of Color) students and scholars. This is an essential shift C | Proportion of female to male investigators GeoPRISMS from long-standing inequities to ensure our Geoscience Community 1.00 MARGINS ■becomes and remains truly just, inclusive, equitable, and diverse. 0.75 0.50 Figure 1. Demographics for the GeoPRISMS and MARGINS 0.25 2005 2010 2015 2020 programs. Data have been collected by the GeoPRISMS 0 Office and the National Science Foundation. Please refer to 2000 p.73 for the list of GeoPRISMS Meetings and their full titles. 85Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Meet the GeoPRISMS Community Early-Career Researcher Profiles Dr. Sarah Jaye Oliva Dr Sarah Jaye Oliva graduated from \" I learned about the GeoPRISMS program early in the first year Tulane University in 2020. At the time of my PhD. Since then, I have attended numerous meetings of publication, Sarah is a postdoctoral and even contributed as breakout leader, scribe, and early- research fellow at the University of British career symposium presenter. In most of those meetings, I received some sort of travel and/or lodging assistance which Columbia in Canada. made participation very accessible in the first place. More information about Sarah's research During the AGU Fall Meeting in my second year of PhD, I can be found on her personal website at presented my poster at one of the GeoPRISMS workshop. I remember explaining my poster and referencing an author’s https://olivasarahj.wordpress.com/ work without knowing that the said author was the person I was talking to! It was a bit embarrassing, but it also signaled Right page: top: Sarah with peers the beginnings of my integration into the community as I James Muirhead, Tobias Fischer, and got to know the faces to match the names I read in papers. Amani Laizer during a field campaign Despite that hiccup, I was pleasantly surprised that I got in Tanzania. Photo credit: J. Muirhead. awarded Honorable Mention in the GeoPRISMS Student Prize for a poster presentation. Before GeoPRISMS, as an Bottom: GeoPRISMS offered the international student in a new academic community, I felt opportunity to Early Career Researchers like the scientific community was too big and unnerving, but the opportunity to discuss my work and be recognized for it to present their work and interact within the GeoPRISMS crowd gave me the affirmation and with peers at meetings. Here, Sarah confidence that I was part of the community. is presenting her poster at the 2019 I learned a lot from the many talks I have attended at GeoPRISMS meetings. They helped me better digest the GeoPRISMS TEI Meeting. context in which my own work existed. The interdisciplinary take on the many breakout discussions was a welcome challenge because I was stimulated to think hard about how my field - and its limitations - might fit in the framework of the big overarching science questions, how results from other fields might impact my own interpretations, and what future direction might be. GeoPRISMS provided valuable training, especially to Early-Career Researchers such as myself. 86 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

GeoPRISMS has allowed me to get to know and but I am proud of all that was accomplished and glad to connect with other researchers working in rifts – have had the chance to be a part of it and to meet all the fellow seismologists and those working in different but wonderful people in it - special shoutout to the GSOC complementary fields. I met peers I could communicate and the superheroes Anaïs and Jo Ann who organized and bounce ideas with, and experience of pursuing all meetings so flawlessly! Even as the program ends graduate studies. I met mentors I could seek advice from officially, I hope the emphasis on collaboration and on my research and career prospects. I met researchers the effort towards training and involving Early-Career with whom I would later co-convene my first AGU Fall Meeting session. It was during the 2019 GeoPRISMS \"Researchers that GeoPRISMS embodied so well will TEI that I shyly approached and introduced myself to a particular researcher, explained my future plans and continue in the community. asked for advice on looking for postdoctoral positions. He answered my queries, suggested names I could reach out to – which I did – and now I am a postdoctoral fellow with one of those names. Networking at GeoPRISMS helped me find a job! It was also thanks to a GeoPRISMS-funded project that I was able to travel to one of my study areas to assist in important fieldwork to omneeaosuf rteheCmOo2stdaemgaaszsiinngg in Tanzania. I consider this experiences of my career thus far, where I saw firsthand the scale of the geological features I studied, met locals who are some of the direct stakeholders to research that I write about, and collaborated with a truly multidisciplinary team. That collaboration enabled by GeoPRISMS resulted in the first Nature publication that I have coauthored! I feel incredibly fortunate that the GeoPRISMS program existed throughout my PhD since day one. GeoPRISMS supported me as an Early-Career Researcher and provided me with the valuable opportunities to connect with like-minded researchers working in related problems, through which I have found peers and mentors that have helped me in my academic journey thus far. GeoPRISMS witnessed me progress in research expertise through the years and grow in confidence to speak more and take on more responsibility in meetings. I am a little sad that the program is nearing completion, 87Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Meet the GeoPRISMS Community Early-Career Researcher Profiles Dr. Zachary Eilon Dr Zachary Eilon completed his PhD at Columbia \" The GeoPRISMS program has been an integral part of University in 2016 and then moved on to conduct my early career. GeoPRISMS first arrived on my radar in postdoctoral research at Brown University. Since 2012, when as a graduate student I recall being bemused by the alphabet soup of sub-fields among SCD/RIE and 2016, Zach has been an Assistant Professor at leftover SubFac/SEIZE/RCL/S2S options as I filled out the University of California Santa Barbara. the application for the student prize. Little did I know how important the GeoPRISMS program would be to my More information about Zach's research can be then and future research. Since that time, I have enjoyed found on his website at attending multiple TIEs, pre-AGU mini-conferences - including convening one on ENAM science directions, http://zeilon.squarespace.com/ and mid-AGU soirées (both formal and informal!). I was fortunate enough to win a student presentation award Right page: Zach installing a seismic station in 2015, and have enjoyed judging many student posters during the 2014 iMUSH experiment; and talks since then, particularly getting into the thick of the science when fuelled by canapés and beverages at the convening the ENAM GeoPRISMS Mini- evening events. As a student, I benefited from travel funds Workshop at the 2017 AGU Fall Meeting and conference support, and received my first invitation to give a keynote presentation from this program. As an early career faculty member, I have been lucky to be funded by the GeoPRISMS program both for science and as co-convener for the 2019 synthesis conference. My scientific perspective and network has been significantly shaped by the GeoPRISMS community. The RIE initiative, where my work on continental extension found a home, successfully balanced geographic specificity with examination of general processes. As a community, we have made substantive advances in understanding the role of fluids and volatiles, depth- and time-variation of strain localisation, and the role of magma within rifts. 88 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

These advances, and my own perspective on plate While substantive work still needs to be done to boundary science, have been shaped by GeoPRISMS’s ensure our research networks are truly inclusive and multidisciplinary outlook; GeoPRISMS conferences are equitable, this program has conscientiously intertwined the rare venues where one can always find practitioners community building and empowerment of early career of different sub-fields talking with, rather than past, scientists with scientific excellence. My sincere thanks each other. go to the leadership and administrative teams who have I am no doubt biased, but I believe that the strongest worked so hard for this last decade to execute the vision aspect of the GeoPRISMS program has been its support for early career scientists. Early career symposia \"of this multidisciplinary program with such remarkable allowed graduate students to present cutting-edge findings to a low-pressure group of peers. Poster and success. oral competitions shone spotlights onto early career research through prize judging that frequently brought grizzled world experts into conversation with fresh- faced students. GeoPRISMS created networks of peers at every level. Most of my current funded grants and collaborations are rooted in relationships built through these networks. Through careful planning and tending of its programs by the leadership team and the tireless Anaïs, GeoPRISMS managed to shrink down the impersonal mass of scientists and subfields, that too often overwhelms young scientists arriving at AGU, into a warm community of familiar faces. I would also like to mention that one of the signature qualities of GeoPRISMS as an NSF program has been the evident care, involvement, and dedication of our program officers, particularly Jenn Wade and Debbie Smith. They have been a constant, candid, and cheerful presence at meetings. They are clearly passionate about the science and the community of investigators and students under the GeoPRISMS umbrella. We have been lucky to have them. Although it feels clichéd to end on this note, a central legacy of the GeoPRISMS program for me will be the personal friendships it has helped spark. I am grateful to the GeoPRISMS Office for cultivating the mutually reinforcing qualities of good community and good science. 89Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Meet the GeoPRISMS Community Early-Career Researcher Profiles Dr Maryjo Brounce completed her PhD at the University of Rhode Island and the Smithsonian Institution in 2014. From 2014 to 2016, Maryjo conducted postdoctoral research at the California Insitute of Technology. Since 2016, Maryjo has been an Assistant Professor at UC Riverside. More information about Maryjo's research can be found on her website at https://sites.google.com/prod/ucr.edu/brounce \" Dr. Maryjo BrounceMy name is Maryjo Brounce and I am an assistant occasion, by ably highlighting the work most relevant to professor in the Department of Earth and Planetary my own, as well as providing a comfortable space to meet Sciences at the University of California Riverside. I am a new people and learn about their work. The townhall proud product of and participant in the NSF community meetings at AGU in particular emphasized to me from focused programs MARGINS and GeoPRISMS and am the very start of my graduate studies the importance of the third generation of female scientists supported by crossing disciplines to find accurate constraints on the these efforts. Broadly speaking, without the support of workings of plate tectonic processes. MARGINS, I would not have successfully navigated graduate work at the University of Rhode Island and In particular, as a graduate student I was provided the Smithsonian Institution, and without the support of funding from GeoPRISMS to attend a site planning GeoPRISMS, I would not now be focused on developing meeting for the East African Rift focus site in 2012. I an independent program of new and exciting research attended knowing very little about the problems that as an assistant professor. I have been directly funded rocks from this area could address and knowing even by both programs, but support from them extends fewer individuals attending the meeting. I write to you significantly beyond the monetary. I have attended now, a handful of years later, as an assistant professor focus site meetings hosted by the GeoPRISMS program with my first funded proposal as Principal Investigator where I met and established a support network of from GeoPRISMS to work on tephras from East African colleagues and fellow students, some of whom are Rift volcanoes. This one meeting, which unfolded over now my collaborators and encourage new creative the course of only a few days, provided me with the and careful science. I have also participated in student basic tools necessary to begin crafting what would presentation opportunities at the AGU Fall Meeting and become a successful proposal to the National Science focus site meetings. These presentations have helped Foundation. I am sure, reader, you can appreciate how me to develop my voice as a scientist, earn recognition this may support the moral of a new assistant professor, for my efforts, then later as a judge for these programs, and if you happen to be one of the people in attendance my voice as a colleague and mentor. I am very grateful at that meeting, I offer my gratitude. for these programs. The GeoPRISMS presence more These programs are among the top factors in shaping broadly pervades large meetings like AGU, where one - the path of my early career. It has been a real privilege especially in early career stages - could be easily lost and to engage with the collegial and community-minded overwhelmed. The GeoPRISMS community has served scientists they attract, and I look forward to seeing more as an anchor for me in these settings on more than one of similar efforts in the future. 90 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

Drs. Hiroko Kitajima and Tamara Jeppson both received GeoPRISMS Postdoctoral Fellowships. Hiroko is an Associate Professor at Texas A&M University. Tamara is now a Postdoctoral Researcher at the U.S. Geological Survey. Dr. Hiroko Kitajima \" & Dr. Tamara Jeppson My first involvement with GeoPRISMS was from geophysical surveys (Kitajima and back in 2008 when I attended the MARGINS Saffer, 2012; Kitajima and Saffer, 2014; Workshop on the Next Decade of the Kitajima et al., 2017). Seismogenic Zone Experiment (SEIZE). I was Later in 2016-2018, I served as a supervisor a graduate student, pursuing a Ph.D. at Texas of another GeoPRISMS Postdoctoral fellow, A&M University at that time. MARGINS Tamara Jeppson. We met for the first time and GeoPRISMS workshops have some at Penn State in 2011 when Tamara came to focuses on specific scientific themes, so their learn some laboratory techniques. Tamara size is perfect for early-career researchers to also became the new owner of my cat, develop networking. My research interest Vivian, because I was about to move to Japan focuses on understanding the mechanics of to take a new job. After I came back to Texas earthquakes and faulting in subduction zones A&M, Tamara and I started discussing her by characterizing deformation behaviors and postdoc research topic when we were at the mechanical/hydraulic/physical properties of GeoPRISMS Theoretical and Experimental the rocks through laboratory experiments. Institute on Subduction Cycles and Thus, it has been aligned well with the Deformation in 2015. The research focuses MARGINS Seismogenic Zone Experiment (SEIZE) and the GeoPRISMS Subduction on defining elastic, plastic, and viscous Cycles and Deformation (SCD) initiative. deformation behaviors of shallow subduction zone materials by performing high-pressure The postdoctoral fellowship is another critical and high-temperature consolidation and component of the GeoPRISMS to support creep experiments on samples of incoming the career development of early-career researchers. I was awarded the MARGINS/ sediment obtained during ocean drilling GeoPRISMS Postdoctoral fellowship in 2011- projects at the Nankai, Aleutian, and Sumatra 2012 under the supervision of Demian Saffer subduction zones (Jeppson and Kitajima, in- and Chris Marone at the Pennsylvania State prep.). University. Demian and I had met at various Although GeoPRISMS is sunsetting meetings including MARGINS workshops, successfully, many scientific questions but we solidified a plan for the proposal at remain unanswered. Community efforts and the NSF-MARGINS Successor Planning also international collaborations continue Workshop in San Antonio, TX. In the to be crucial to tackling such scientific research, we focused on the estimation of the problems. I look forward to seeing the in-situ stress states and pore pressure in the new research community that facilitates Nankai subduction zone, by incorporating collaborative research and provides career laboratory deformation experiments under development opportunities for early-career simulated loading conditions and the data scientists. 91Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Program Highlights Pairing community seismic experiments with seismic community development Aubreya Adams (Colgate University) and Maureen Long (Yale University) Ahallmark of the GeoPRISMS Program has been its support of community seismic experiments in the Eastern North American Margin (ENAM) and Alaska & Aleutians primary sites. These projects were funded specifically as data collection efforts - the data analysis was provided through separate awards. The projects involved a large number of Principal Investigators (PIs), and were planned and executed with extensive community input. The large and comprehensive geophysical datasets collected during the GeoPRISMS community experiments were made immediately publicly available, enabling a wide range of scientific investigations by the community. These experiments have allowed for the collection of large-scale, onshore-offshore datasets, altogether more ambitious than any that could have been realistically carried out by individual researchers. These deployments were designed to enable imaging of the crust and mantle across the shoreline, over multiple scales, using both active- and passive-source imaging approaches, to address the full range of science questions that have been articulated for each GeoPRISMS primary site. In June 2019, seven undergraduate students, selected from a national pool of 54 applicants, participated in an AACSE short course in Kodiak, AK, led by PI Aubreya Adams (Colgate University). During the week-long experience, participants were immersed in a short but intensive course introducing topics in seismology, plate tectonics, and the tectonic history of Alaska. A fieldtrip led by Peter Haeussler (USGS) and Gary Carver (Humboldt State University) introduced students to the geology of accretionary prisms. Finally, the group joined PI Lindsay Worthington (UNM) in the recovery of 398 nodes in eastern Kodiak. Photos credit: A. Adams and J. Nakai. 92 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

The Science Party and Apply-to-Sail graduate students during the September 2014 Photo credit: A. Sheehan OBS deployment campaign part of the ENAM Community Seismic Experiment. Photo credit: D. Dubois. A unique aspect of these GeoPRISMS community experiments is their substantial investments in the professional development of future earth scientists through a range of educational and experiential activities. The 2014-2015 ENAM Community Seismic Experiment (ENAM CSE) and the 2018-2019 Alaska Amphibious Community Seismic Experiment (AACSE) joined a series of community projects that have helped scientists, particularly students and early-career investigators, to gain experience with seismic data collection. These included marine seismic data acquisitions through the Apply-to-Sail program and onshore active-source data field campaigns. Additionnally, each project offered experiential opportunities through hands-on workshops, targeted to different populations within the community. Such programs are critical to expanding access to seismic research - particularly in marine settings - to new communities, maximizing the utilization of data collected in community experiments, and recruiting and retaining a more diverse community of earth scientists. The ENAM CSE solicited community participation in data collection on four cruises and two onshore field campaigns during 2014-15. Participation was open to the broad geoscience community, with an emphasis on participation by students and early-career investigators. In total, 79 scientists and students from 49 different institutions participated in an ENAM CSE fieldwork. The AACSE cruises expanded the Apply-to-Sail program by inviting applicants from all career stages to participate in five cruises between 2018 and 2019. A total of 32 accepted participants included K-12 teachers, undergraduate and graduate students, postdoctoral researchers, mid-career professionals, and both tenured and untenured faculty members. Participants in both the ENAM CSE and AACSE cruises and field campaigns contributed to all aspects of on-board and field science activities, including instrument preparation, deployment, surveying, and recovery, initial onboard and field data collection and processing, documenting dives of the ROV JASON (in the case of AACSE), and contributing to public outreach through live field blogs. 93Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Data collected by community experiments are publically available field experiences or courses in geophysics. The workshop included and workshops were held for both projects to train students and new a presentation of the scientific goals of the AACSE, an introduction investigators with the goal to maximize the utilization of project data. to passive-source seismic data, how to access seismic data, and an Two week-long workshops focusing on ENAM CSE data processing, overview of earthquake location. The workshop concluded with and aimed primarily at graduate students and early-career scientists, several days of field work during which students helped to recover were held in 2015 at the University of Texas Institute for Geophysics 398 nodal seismometers deployed across eastern Kodiak. and at the Lamont-Doherty Earth Observatory of Columbia Community projects not only play a valuable role in addressing large- University. Participants in the refraction workshop learned to plot scale scientific problems, but also play a critical role in engaging the Ocean Bottom Seismometer data, pick arrivals, formulate a starting scientific community and promoting access to seismic data - and model, and carry out tomographic inversions, while each participant the acquisition of data - to new populations. The successful calls for in the reflection workshop processed one of the reflection profiles community involvement in the ENAM CSE and AASCE projects from raw shot gathers to a migrated image. have broadened participation in data collection and provided Access to seismological research is limited for many undergraduate experience with data processing and analysis that is critical for future students, especially those attending small or minority-serving investigators. The ENAM CSE and AASCE demonstrated that this institutions. In order to increase the engagement of scientists at engagement may be expanded using workshops to train additional the undergraduate level, the AACSE hosted in the summer 2019 scientists in data processing to maximize data usage and to recruit a week-long workshop in Kodiak, AK for undergraduates from across the US, with priority given to those with limited access to ■and retain undergraduate students for seismic research and graduate study, promoting diversity among the next generation of scientists. 94 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

Hours of watch stands, deploying and retrieving instruments, learning and applying data processing, seating in lectures focusing on the areas of study, the duties of Apply-to-Sailors are as numerous as they are varied. The learning curve might be steep but the experience is rewarding. Photos credit: A. Bécel 95Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

Program Highlights GeoPRISMS Data portal: A decade of community support Andrew Goodwillie and the Data Portal Team Lamont-Doherty Earth Observatory, Columbia University GeoPRISMS-funded projects have in many cases undertaken Over the past decade, the Data Portal team has worked closely fieldwork involving expensive facilities and instrumentation with many GeoPRISMS Principal Investigators to ensure that in remote locations, sometimes for non-repeatable events. their datasets are appropriately catalogued and archived, including The GeoPRISMS community data resources support GeoPRISMS supporting the open data access requirements for a number of research by helping to preserve these unique datasets thus increasing the return on a decade of investment in the GeoPRISMS program community experiments. Data Portal team members have led made by the National Science Foundation. These data resources webinars and mini-workshops sponsored by GeoPRISMS and have interacted with the GeoPRISMS community at many meetings provide a range of benefits that include enabling sharing and reuse and conferences. Data Portal updates are regularly shared with the of data, improving data access, promoting scientific reproducibility, community via the GeoPRISMS newsletter and through reports and supporting the principles of FAIR data (Findable, Accessible, presented at the GeoPRISMS Steering and Oversight Committee Interoperable, Reusable), encouraged by professional societies such meetings. The Data Portal group works closely with the GeoPRISMS as AGU. The preservation of GeoPRISMS data additionally helps to Office, particularly in identifying publications to be added to the fulfill the requirements of NSF funding and journal publication, and GeoPRISMS bibliography. underpins a robust data legacy for the program. The GeoPRISMS Data Portal is part of the Marine Geoscience Data The GeoPRISMS Data Portal was established in 2011 to provide System (MGDS) and provides links to a number of community data convenient access to data and field information for each primary systems and resources (Fig. 1). These include the EarthChem Library site as well as to other relevant data resources. The GeoPRISMS Data and the EarthChem Portal for geochemistry data, the System for Portal grew out of the MARGINS Data Portal and has been regularly Earth Sample Registration (SESAR), the Academic Seismic Portal, enhanced with functionality that reflects new capabilities in database the Global Multi-Resolution Topography (GMRT) synthesis, and infrastructure, architecture, and interactivity. The GeoPRISMS Data GeoMapApp for data visualisations. From the Data Portal, external Portal is part of a broader suite of NSF-funded data collections and links point to data collections at IRIS and UNAVCO. All of these resources, with other examples including EarthChem, IRIS and data resources serve to support GeoPRISMS data integration and UNAVCO, that support GeoPRISMS-related research. synthesis efforts. GEOPRISMS DATA PORTAL WWW.MARINE-GEO.ORG/PORTALS/GEOPRISMS MARINE GEOSCIENCE DATA SYSTEM EARTHCHEM LIBRARY Geophysical-geological data repository SESAR and metadata catalogue GeoPRISMS and MARGINS data EXTERNAL DATA REPOSITORIES collections academic seismic portal E.G. IRIS, UNAVCO GEOMAPAPP GLOBAL EARTHCHEM Fig. 1. The GeoPRISMS Data Portal links to both MULTI-RESOLUTION DATABASE local and external data repositories and resources TOPOGRAPHY in support of GeoPRISMS research. DATA VISUALIZATION DATA SYNTHESES 96 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

Several of these data collections and syntheses were enhanced to help GeoPRISMS researchers with field planning and implementation. Swath bathymetry data from hundreds of cruises were added to the GMRT synthesis within the GeoPRISMS primary sites. A particular focus has been placed on the Alaska-Aleutians, Cascadia, and Eastern North American Margin study areas to help facilitating the large multidisciplinary GeoPRISMS field programs in those regions. High quality bathymetry data make the deployment and recovery of ocean-bottom seismometers (OBSs) much easier when available. In parallel, Aleutian arc geochemical analytical data from more than fifty papers published between 1971-2010 were added to the EarthChem-PetDB database. The data are available through the EarthChem Portal and GeoMapApp. The GeoPRISMS Data Portal provides links to almost 200 datasets Fig. 2. Example of GeoPRISMS data sets on the contributed by the GeoPRISMS community covering all five primary data portal data sets page which provides links sites and a wide range of disciplines (Fig. 2). A DOI has been issued for many of these datasets to facilitate their citation in publications. to data and field program information. Search For Data | The search tool provides a quick way to find GeoPRISMS data using parameters such as keyword, NSF award The active-source seismic data from the 2015 SEGMeNT survey are number, publications, and geographical extent. now available on the Data Portal. This integrated study of tectonic Contribute Data | Researchers can contribute any GeoPRISMS- and magmatic processes during the onset of rifting, led by Shillington related datasets that are of interest to the community by using the et al., focused upon the northern Malawi (Nyasa) rift, a region of data submission form: http://www.marine-geo.org/submit/ early-stage rifting in strong, cold lithosphere (Fig. 4). The study imaged sedimentary and crustal structure within and around the Examples of contributed data sets lake. The dataset is available at : http://www.marine-geo.org/tools/search/entry. To exemplify the range of data available through the portal, a few php?id=EARS_SEGMeNT datasets are highlighted below for each of the five GeoPRISMS Aeromagnetic total magnetic intensity data were collected in 2013 primary sites. Many GeoPRISMS datasets are also available in for the Karonga area of northern Malawi Rift, and contributed by GeoMapApp under the Focus Site and DataLayers menus. investigators Estella Atekwana, Jalf Salima, and Leonard Kalindekafe. Alaska-Aleutian arc In addition, 2-D electrical resistivity tomography profiles acquired in the same area in 2015 were provided by Estella Atekwana, The Key et al. 2015 amphibious investigation of the magmatic system Daniel Lao-Davila, and Folarin Kolawole. The data were used by beneath Okmok Volcano collected magnetotelluric (MT) time series the researchers to study the early stages of continental extension data offshore the eastern Aleutian arc island of Umnak, AK. The and active deformation of the Malawi Rift North Basin hinge zone. data were collected along a 300km-long transect perpendicular to Cascadia the subduction trench and the MT stations comprised more than The Gao and Shen 2014 shear wave velocity model of the upper fifty broadband ocean-bottom electromagnetic receivers. All except mantle from full-wave ambient noise tomography is available. It one were recovered. reveals low-velocity anomalies along the Cascadia back-arc that are spatially correlated with the three arc-volcano clusters. http://www.marine-geo.org/tools/search/entry. Derived from Cascadia Initiative OBS data, Emily Morton and Sue php?id=Aleutians_Bennington Bilek contributed a new microseismicity catalogue of earthquakes detected and located offshore central Oregon from 2011 to 2015. The The geochemical-geophysical study of the Aleutian arc Unimak- catalog (Fig. 5) was generated using a subspace detection technique Cleveland corridor, led by Diana Roman, Erik Hauri, and Terry and includes hypocentral locations and duration magnitudes. Plank, include helicopter-derived chemistry data for volcanic trace gas emissions at Mount CusleinvgelaanMduvltoi-lGcaAnSo.syCstOem2, ,SaOre2,daenscdriHbe2dS concentrations, measured in Werner et al., 2017 and can be explored in GeoMapApp (Fig. 3). East African Rift System (EARS) Erica Emry contributed grids of upper mantle isotropic seismic velocity structure beneath Africa. Derived using new full-wave seismic tomography techniques on ambient noise and earthquake data, the grids shed light on relationships between mantle flow, cratonic lithosphere and surface processes. The dataset is available at IRIS-EMC and has been added to GeoMapApp (Fig. 3). 97Fall 2020 Issue No. 43 GeoPRISMS Newsletter •   

The dataset is available at: http://www.marine-geo.org/tools/search/entry.php?id=Cascadia_Morton Subduction zone heat flow datasets from H. Paul Johnson, Evan Solomon, Robert Harris, and Marie Salmi were contributed for surface heat flow measurements collected during an R/V Atlantis cruise in 2013. These include heat flow data acquired with a multi-core logger, thermal blankets, and an Alvin heat flow probe that were deployed using the Jason II remotely-operated vehicle. The investigators also contributed the Salmi et al. 2017 heat flow data derived from Bottom-Simulating Reflectors (BSR) that were imaged using active-source multi-channel seismic data from the 2012 Cascadia Open Access Seismic Transects (COAST) survey. The BSR-related fieldwork was conducted along the southern Cascadia margin during the R/V Langseth expedition MGL1212. As part of the project investigating the thermal structure, hydration, and dehydration of the Juan de Fuca plate, investigators Helen Janiszewski, Jim Gaherty, and Geoff Abers contributed stacked receiver function data files and station orientation estimates for Cascadia Initiative OBS stations. The dataset is referenced in Janiszewski and Abers, 2015. Closely related, multi-channel seismic field and processed datasets from the Juan de Fuca Ridge2Trench experiment were contributed by investigators Shuoshuo Han, Suzanne Carbotte, and Pablo Canales and are available on the MGL1211 cruise page. From top to bottom: Fig.3. Werner et al. CO2 gas trace concentration at Mount Cleveland, AK from a helicopter survey conducted in August 2015. The dataset is available in the GeoPRISMS data portal and in GeoMapApp under both the Geochemistry and Focus Sites menus. In this image the symbols indicate the helicopter flight path and have been colored blue (low CO2 concentration) to red (high). The background map is the Global Multi-Resolution Topography (GMRT) synthesis which incorporates the USGS NED land elevation data for the Aleutian arc. Image made with GeoMapApp. Fig. 4. Shear-wave velocity structure at 123km depth from Emry et al. This, and similar grids for depths between 105 and 424km are provided in GeoMapApp. The grids reveal segmented, low‐velocity upper mantle underlying the magmatic northern and eastern sections of EARS. Shallow parts of the southern and western sections are dominated by high‐velocity upper mantle which transitions at depth to low velocities. Image made with GeoMapApp. Fig. 5. Interactive map showing the active-source multi-channel seismic profile lines collected during the Shillington et al. 2015 EARS SEGMeNT survey. The information popup window provides details of the selected seismic line and a link to the data from that line. The background map is the Global Multi-Resolution Topography (GMRT) synthesis. Lake Malawi is the flat, even green feature underlying the yellow profile lines. Image made with MGDS Map Viewer using a Google Maps display engine. Fig. 6. Map of the Cascadia region showing north-south-trending 10km depth contours of the subduction slab interface from McCrory et al. The dots represent the microseismicity catalogue from Emily Morton, colored following earthquake focus depth and scaled on duration magnitude. The red arrows are geodetic velocity vectors from the UNAVCO EarthScope PBO solutions in the IGS08 reference frame, with 10mm of arrow length equivalent to a velocity of 10mm/ year. The EarthScope PBO geodetic velocity vector data are available under the GeoMapApp Portal menu. Image made with GeoMapApp. 98 • GeoPRISMS Newsletter Issue No. 43 Fall 2020

New Zealand Nathan Bangs and Adrien Arnulf led a large team of investigators during the 2017 Langseth SHIRE cruise MGL1708 to study the along- strike variations in locked and creeping megathrust systems off the Hikurangi convergent margin in New Zealand (Fig. 7). The data from the 2-D active-source multi-channel seismic survey are available. Multi-channel seismic shot field data and seismic navigation files were contributed by investigators Nathan Bangs, Shuoshuo Han, Greg Moore, Eli Silver, and Harold Tobin for the follow-on 2018 Langseth active-source 3-D seismic survey across the Hikurangi margin. In this survey, four closely-spaced streamer cables were towed within a 15km x 60km survey box across the trench and forearc. The Hikurangi margin is characterised by regularly-occurring slow-slip events (SSEs) and one of the main goal of the survey was to gain understanding of the factors associated with slow-slip behavior. The seismic data sets are available at: http://www.marine-geo.org/tools/search/entry.php?id=MGL1801 To better understand the forces that drive early-stage subduction, investigators Mike Gurnis, Sean Gulick, Joann Stock, Harm Van Avendonk, and Rupert Sutherland conducted a 2-D active-source survey of the Puysegur segment of the Macquarie Ridge Complex. This Puysegur-Fiordland boundary south of New Zealand’s South Island represents a type-example of incipient subduction. The 2018 Langseth cruise, dubbed “SISIE”, collected multi-channel seismic reflection data which may be viewed at: http://www.marine-geo.org/tools/search/entry.php?id=MGL1803 Eastern North America Margin The main offshore component of the multi-PI, shoreline-crossing Fig.7 (top). Seismic survey lines (yellow) from the 2017 ENAM Community Seismic Experiment took place in 2014. The shots Langseth SHIRE survey, MGL1708 (Bangs et al.). The from the Langseth cruise MGL1408 were recorded by streamers and OBS offshore, and by broadband and short-period seismometers on background elevation map is the Global Multi-Resolution land. Multi-channel seismic shot data and field information from Topography (GMRT) synthesis. Image made with MGDS the experiment, including land seismometer operations and OBS Map Viewer using a Google Maps display engine. deployments, were added to the portal (Fig. 8). An updated USGS bathymetric compilation of the ENAM margin Fig. 8 (bottom). ENAM CSE components are indicated was added to GMRT and GeoMapApp. Based upon 32 multibeam as follows. OBS - Short-period (green), broadband swath mapping surveys collected between 1990 and 2015, the new (yellow); Land-based seismometers - short-period compilation covers 725,000km2 of seafloor along the margin. (red), broadband (light blue, Outer Banks), EarthScope USArray (dark blue). The black line shows the ship track for Langseth cruise MGL1408 led by co-chief scientists Donna Shillington, Anne Bécel, and Matt Hornbach. Image generated in GeoMapApp. The station locations are available under the Focus Sites > ENAM menu. GeoPRISMS bibliography With more than a hundred papers stemming from GeoPRISMS-funded research, the GeoPRISMS references database can be searched by primary site, paper title, author, year, and journal. Many of the citations are tied to data sets. Send us the DOI citation for your papers for inclusion in the bibliography. The GeoPRISMS Data Portal will continue to operate and be available after the official end of the NSF-funded GeoPRISMS decadal program in order to facilitate the proper cataloguing and archiving of GeoPRISMS data, including data generated from the more recent rounds of NSF solicitations for proposals that sought GeoPRISMS funding for data synthesis and integration efforts. The Data Portal team will also ■be involved in an NSF-funded workshop that will take place soon, with a focus upon establishing a robust GeoPRISMS data legacy. The GeoPRISMS Data Portal team is here to serve the community Please contact us at [email protected]

102 Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS)- Revealing the environment of shallow slow slip 104 Preliminary findings from the NZ3D 3D seismic imaging experiment 106 Unraveling the effects of upper plate lithology and stress on seismic velocities at Hikurangi 108 How are large eruptions different? Reconstructing changes in magma reservoirs in the Taupo Volcanic Zone 110 SISIE: South Island, New Zealand, Subduction Initiation Experiment 112 Slow-Slip and Fluid Flow Response Offshore New Zealand (SAFFRONZ) - Probing the nature of the Hikurangi margin hydrogeochemical system 113 Deformation and anisotropy of antigorite 114 Slow slip events in Cascadia and New Zealand 116 The Deschutes Formation: North America's most recent arc-related ignimbrite flare up. 118 Small-scale mantle convection in the back-arc modulates volcanic activities along the Cascade arc 119 Unravelling monogenetic volcanism in the Oregon Cascades 120 Physical properties of Cascadia incoming sediments 122 Seismic characterization of the Juan Fuca plate from ridge to trench 124 Constraining the temperature conditions of paleo-subduction plate interfaces 126 Mélange-peridotite interactions in the source of arc magmas 128 Uplift and exhumation history of the central Aleutian Arc 130 Tracking carbon from subduction to outgassing along the Aleutian Subduction Zone 100 • GeoPRISMS Newsletter Issue No. 43 Fall 2020