Monday, March 30th

Astrobiology + Planetary Science

Haskelle White-Gianella Leveraging crustal oxidation experiments to assess the plausibility of liquid water on ancient Venus 

Whether Venus was once a habitable planet is a longstanding question in planetary science and astrobiology. Currently, it is unknown why Venus's climate evolution diverged drastically from Earth's. If Venus was once a habitable, ocean-bearing planet, then surface water likely evaporated into water vapor as temperatures rose to modern levels (460 °C). High stellar UV fluxes photolyze atmospheric H2O and drive preferential H escape, potentially leading to the build-up of abiotic O2. However, there is virtually no oxygen in Venus' modern atmosphere. 

To reconcile past habitability with water loss and oxygen accumulation, we look at the efficiency of crustal oxidation as an oxygen sink on Venus. If crustal Fe2+ can react with atmospheric oxygen, then the oxygen is permanently removed to form hematite or magnetite. However, the efficiency of crustal oxidation under Venus-like conditions is poorly constrained. Here, we plan to perform high-pressure, high-temperature experiments to determine if early habitability can be reconciled with the modern O2-limited atmosphere.

Methods: We developed a novel high-pressure, high-temperature experimental system to simulate both modern and post-accretion Venus conditions (100-300 bar; 700-900 K). To measure the crustal oxidation rate, basalt samples will be placed in the chamber under Venus-like conditions with an O2-CO2 gas mixture for 1-3 weeks. After exposure, the samples will be analyzed to measure the proportions of iron redox phases and, thus, the oxidation state. 

Expected Outcomes: If crustal oxidation is found to be efficient at removing atmospheric O2, this could potentially explain the lack of O2 in the modern atmosphere, making a habitable past possible, though not required. If crustal oxidation is found to be an inefficient O2 sink, then crustal oxidation cannot explain the modern Venus atmosphere, and limits the potential for past habitability. In either scenario, this work will help us decipher Venus' enigmatic past. 

Alexandra Papesh Modeling Venus’ atmosphere-interior evolution to assess habitability prospects for rocky planets at the inner edge of the habitable zone

Understanding the atmosphere-interior evolution of terrestrial planets is crucial for anticipating the long-term habitability of rocky exoplanets. Numerical planetary evolution models can be used to investigate what factors control habitability on rocky planets, and Solar System planets provide an invaluable opportunity to ground truth such models. In particular, the history of Venus remains poorly understood, and although Earth and Venus are believed to have formed from comparable starting materials and at similar orbital separations, their surface climates are now extremely different. It is not known whether Venus’ surface was habitable in the distant past when the sun was dimmer, or whether Earth and Venus diverged immediately after formation. Understanding Venus’ atmospheric evolution and potential past habitability is important because Venus may be representative of a large population of ~Earth-sized exoplanets which orbit near the inner edge of their host star’s habitable zone. Thus, determining whether Venus was habitable in the past may have implications for the prevalence of habitable environments in the universe. 

Here, we present the results of exploring Venus’ past with a fully coupled magma ocean, redox, fractionating atmospheric escape, and climate evolution model for terrestrial planets. The model simultaneously solves for radiative-convective climate, thermochemical equilibrium, and atmosphere-interior magma ocean volatile partitioning throughout magma ocean solidification (Krissansen-Totton et al., 2024). We find that early Venus could have possessed a range of early atmospheres that are much more diverse than the oxidized, H2O+CO2 dominated, post-accretion atmospheres that are typically assumed for magma ocean models. For Venus, we find only a narrow range of initial volatile inventories may permit habitability, and that high albedo is necessary regardless of magma ocean redox state. Ongoing work will apply similar calculations to inner edge rocky exoplanets to more fully characterize their habitability prospects as a function of composition, redox state, and orbital separation.

Lauren Kafadarian High throughput experiments to constrain icy moon oceanic properties

Ultrasonic sound speed measurements (USSMs) are currently the most accurate method to derive crucial oceanic thermodynamic properties for icy moon geophysical exploration (e.g. density, heat capacity, bulk modulus, thermal expansivity) at the elevated pressures found inside extraterrestrial oceans, in excess of 700 MPa. However, the existing method to collect USSMs at high pressures is labor-intensive and low throughput, preventing broad and systematic exploration of the wide range of relevant chemical mixtures. This project addresses these challenges by automating the USSM data collection process. By doing so, it aims to enhance efficiency by tripling the measurement speed. Consequently, comprehensive and complete measurements will be achieved within a matter of weeks, instead of the previous months.

Exploring ocean worlds like Europa, Titan, Ganymede, Callisto, and Enceladus offers the prospect of studying potentially habitable extraterrestrial environments beyond Earth, while simultaneously contributing to our understanding of the origins of life on our planet. Recent spacecraft observations suggest that these moons harbor oceans up to hundreds of kilometers deep beneath thick lithospheres of ice. Upcoming missions such as NASA’s Europa Clipper and Dragonfly and ESA’s Juice to these icy moons will require geophysical modeling of the icy moons' interiors to interpret the synergy between various measurements (e.g. magnetic fields, gravity, surface composition, seismology, in-situ surface and cryovolcanic particles composition). However, insufficient data on the properties of potential ocean compositions will limit the reliability of those analyses unless addressed before the missions arrive at their targets. I will present the automation method developed in this project and preliminary USSM data collected in relevant binary, ternary, and quaternary aqueous solutions (H2O-CH3OH-NH3-NaCl) at various concentrations and solute ratios. 

Tristen Arias Investigating subsurface temperatures in permanently shadowed regions of the Lunar South Pole

Permanently Shadowed Regions of the Moon (PSRs) are commonly found in impact craters near the lunar poles whose rims shield their interiors from the low angled incident solar radiation at high latitudes. The lack of irradiance forms cold traps with temperatures typically ranging from 25-70K, capable of maintaining water ice. The temperature profile below the surface has not been well constrained which prompted the creation of a model which can be applied to various locations in the Lunar polar regions. Investigating PSRs in the Lunar South Pole is of particular interest due to the importance of water ice for the upcoming Artemis III mission, as well as proposed cryopreservation facilities. We’ve used the COMSOL Multiphysics software to develop our model, using properties from lunar sample returns as the basis for our simulated regolith. Starting in 1 dimension, we’ve worked up to 3D, using high resolution elevation data from the Lunar Orbital Laser Altimeter to replicate crater topography. We take a solar constant of 1366 W/m2 and scale it to an average illumination map from NASA PGDA across the surface of the South Pole. Heat is radiated out according to the non-blackbody Stefan-Boltzmann equation using an emissivity of 0.95 for the lunar surface. We validated our model in 1D under equatorial conditions, compared to in situ measurements from the Apollo 17 Heat Flow Experiment which prompted a correction of 1.38 times to the surface emissions. With these current illumination conditions, we produce lower surface temperatures than measured in PSRs, but preliminary results for the 3D model have produced a gradient of approximately 1.5 K/m independent of local surface temperature. We have also seen significant improvements in surface temperature with the introduction of slight heat flux which is scattered into the PSR from the crater walls. These results suggest that with the 1.5 K/m gradient, ideal PSRs can maintain sub 77K temperatures to a depth of 10 meters.

Paleontology, Sedimentology, Paleoclimate

Kunmanee Bupphamanee Nitrogen isotopes in 3.4-3.5 Ga Paleoarchean cherts: insights into early microbial nitrogen cycling 

Nitrogen isotopes have been used to reconstruct nitrogen cycling in early Earth’s environment. Although no nitrogen isotope data have been reported from rocks older than 3.8 billion years ago (Stüeken et al., 2016), existing records suggest life had evolved to grab atmospheric nitrogen by at least 3.2 billion years ago (Stüeken et al., 2015). This leaves over half a billion-year interval during which early nitrogen cycling remains poorly constrained. 

Black chert dikes are common features in Paleoarchean terranes and contains trace of organic matter, yet its origin is debated (Lindsay et al., 2005). Given the scarcity of Archean rock deposits and the low-grade metamorphism experienced by most, these cherts may record the biological influence, which could be valuable for metabolic reconstruction. Previous studies in such rocks have targeted kerogen extracts for nitrogen isotope analysis; however, extremely low nitrogen yields often limit analytical precision and accuracy. In contrast, bulk-rock analyses recover higher nitrogen contents and may better represent primary isotopic signals under low-grade metamorphic conditions (Stüeken et al., 2017). 

Here, we performed bulk analyses of nitrogen isotopic composition in these Paleoarchean cherts that were pre-treated with organic solvent to remove modern contamination. We present 30 additional data points of nitrogen isotope composition for the Pilbara group from three stratigraphy units: Dresser Formation (n=20), Apex Formation (n=9), and Strelley Pool chert formation (n=1). Our data display a narrower range and higher average nitrogen isotope values, from -1.1‰ to 7.2‰, with a mean of 4.3±2.6‰. This elevated nitrogen isotopic composition cannot be readily explained by post-depositional alteration and known abiotic processes. One possible interpretation is that the organic nitrogen could be derived from chemosynthetic organisms near hydrothermal environments.

Hannah Cothren A low oxygen habitat for Earth’s first animal ecosystems: A thallium isotope record of the Avalon Assemblage at Mistaken Point 

Increased global deep marine oxygenation is hypothesized to have sparked the emergence of animal life during the Ediacaran Period. However, Ediacaran paleoredox proxy records do not yield a straightforward signal of increased deep marine oxygenation at or around the rise of animals. Clarifying the link between deep ocean oxygenation and the appearance of animal life requires a proxy sensitive to dissolved oxygen accumulation in global marine bottom waters. We apply such a proxy, thallium isotopes, to the Ediacaran deep-water stratigraphy at Mistaken Point Ecological Reserve, Newfoundland, Canada. These strata host the oldest known diverse animal ecosystems and are an ideal target to test the hypothesized coeval rise of animals and oxygen. Our pilot Tl isotope and redox-sensitive trace metal data suggest transiently oxygenated or low-oxygen habitats of the earliest animal ecosystems and argue against increased environmental oxygenation as a strong trigger on the emergence of animal life on Earth.

Jade Wells Small Microbes, Big Questions: How Were Two-Billion-Year-Old Microbial Buildups Organized? 

Polygonal patterns are widespread in nature. These patterns emerge through a variety of physical and biological processes, including contraction and strain (e.g., mud cracks and basalt columns) and organismal activity (e.g., the hexagonal honeycombs of honeybees). In deep time, some aggregations of microbial mats and stromatolites, the latter being centimeter- to meter-scale laminated buildups, exhibit polygonal organization at the outcrop scale. Understanding the mechanisms that drive the formal organization of such sedimentary structures can provide us with insights into the behavior of early life on Earth and potentially inform the search for biology elsewhere in our solar system. Here, we examine and describe the morphology of 1.9 billion-year-old stromatolite outcrops from the Pethei Group in the Northwest Territories, Canada in an effort to constrain their morphogenesis and test whether their spatial patterns reflect self-organization. Using structure from motion (SfM) photogrammetry, we generate centimeter-resolution three-dimensional (3D) reconstructions of four field sites and digitally trace more than 3,000 individual fossilized microbial aggregations. From these tracings, we quantify spatial organization using metrics such as area, width, length, aspect ratio, circularity, and nearest neighbor distance. We then compute scale-invariant metrics such as polygonality, a measure of how closely an arrangement of shapes resembles an ideal polygonal pattern, to compare the geometry of the studied stromatolites to both abiotic (e.g., mud cracks, basalt columns) and biotic (e.g., extant microbial mats) polygonal systems. Our approach enables us to test various extant hypotheses for stromatolite morphogenesis, including whether the observed polygonal morphologies reflect growth on antecedent topography (e.g., mud cracks) or arise through microbial self-organization. We aim to extend our analyses to additional stromatolites preserved within the rock record to further investigate the relative contributions of environmental and biological factors in the morphogenesis of ancient microbial buildups.

Nissa Stupakoff Taphonomic controls on the fossil record of a high-latitude vertebrate paleoecosystem (Lower-Middle Triassic Fremouw Formation, Antarctica)

The Fremouw Formation hosts the oldest record of tetrapodal vertebrate fossils from Antarctica and has figured prominently in paleontologists’ understanding of vertebrate assemblages at high paleolatitudes of the earliest Triassic. Comparative work between the Fremouw assemblage and coeval assemblages at lower latitudes could uncover key evolutionary and biological patterns across southern Pangaea during the recovery from the End-Permian Mass Extinction. However, to more precisely explore Pangaea’s paleobiological history, we must first characterize and quantify the geologic, taphonomic and sampling filters that determine our ability to reconstruct ancient biodiversity and environments. In this study, we use almost 700 vertebrate specimens housed at the UW Burke Museum of Natural History & Culture and the American Museum of Natural History to assess the taphonomic controls on the overall completeness and quality of anatomical information preserved in the Fremouw assemblage. We use a novel, generalized metric of specimen completeness to quantify each specimen’s skeletal completeness, regardless of taxonomic affinity and specific morphology. We then set this metric against four categories: 1) fossil matrix lithology, 2) inferred depositional setting, 3) taxonomic affinity, and 4) specimen locality. We find that, on average, more complete fossils are found in finer-grained sediments representing mostly lower-energy depositional settings interpreted as primarily fluvial foreland basins proximal to the sediment source. Additionally, although Dicynodont therapsids and temnospondyl amphibians are the most numerous, on average the most skeletally complete groups are archosauromorph reptiles, and therocephalian and cynodont therapsids. These preliminary results suggest that specific depositional settings and body size play prominent roles in filtering skeletal information in the Fremouw fossil record, and hold promise for basin-level comparisons across southern Pangaea.

Sabrina Kainz Carbonates through time, through time: A database of published carbonate U-Pb ages from the last decade and beyond

The ability to precisely date geological materials is essential to reconstruct the timing, magnitude, and causal relationships of events in Earth history. Directly dating carbonate minerals allows us to investigate biological, climatic, and tectonic events, especially in systems where other geochronometers (e.g., zircon or apatite) may not be available. Over the past decade, in-situ uranium-lead (U-Pb) geochronology has become widely used. The high spatial resolution of laser ablation ICP-MS allows dating of multiple paragenetic phases that would be otherwise difficult to differentiate with solution-based techniques. 

Interpretation of U-Pb carbonate data can be difficult because carbonates are typically low uranium, high common lead-bearing minerals that may exhibit complex open-system behavior. Low-temperature fluid reactions can mobilize U and Pb, mixing or partially resetting the U-Pb system, obscuring primary age information, and making it difficult to recognize geologically meaningful data. 

Here, we present a database to understand trends in published carbonate U-Pb dates. Often, measured U-Pb dates are younger than the expected age of the host rock as constrained by biostratigraphy or cross-cutting relationships. We attribute this to post-depositional alteration, which can reset and/or mix age domains, or cause the precipitation of new phases. We examine the initial common Pb composition of carbonates from different environments to compare calculated initial Pb to the Stacey-Kramers model of terrestrial Pb evolution. We also compare global volumes of preserved carbonate stratigraphy, trends in seawater chemistry, and published carbonate U-Pb data across Earth history to identify constraints and opportunities in further application of this technique. 

Hailey Germeau Disequilibrium of Water Column and Sediment Carbonates in the Dual Clumped Isotope Record of Fayetteville Green Lake

Lake sediments are widely used as archives of past climate, yet carbonate-based paleotemperature reconstructions can be biased if carbonates precipitate out of isotopic equilibrium or at depths and seasons that differ from common assumptions. Many paleoenvironmental studies interpret lacustrine carbonates as recording mean summer surface-water temperatures, assuming equilibrium precipitation during annual whiting events. However, growing evidence shows that microbially mediated precipitation and early diagenetic processes can introduce kinetic isotope effects that obscure primary temperature signals.

Dual carbonate clumped isotope thermometry (Δ₄₇ and Δ₄₈) is a powerful tool that allows reconstruction of mineral formation temperatures independent of water isotopic composition. Offsets between Δ₄₇- and Δ₄₈-derived temperatures can also be used to identify isotopic disequilibrium and constrain carbonate growth mechanisms. Here, we apply this method to carbonates from Fayetteville Green Lake (FGL), NY, to evaluate equilibrium and disequilibrium signatures. 

We analyze carbonate particles filtered from the upper 15 m of the water column during summer whiting events, alongside carbonate from a shallow sediment core collected from the lake center. FGL whiting events have been linked to photosynthetic microbial activity, suggesting that water column carbonates may form under isotopic disequilibrium associated with autotrophic metabolisms. Δ₄₇–Δ₄₈ measurements exhibit offsets consistent with this interpretation, indicating that biologically mediated disequilibrium is not restricted to nearshore or early diagenetic environments but can also arise directly within the water column.

In contrast, carbonates from shallow core sediments record temperatures consistent with equilibrium summer surface-water conditions. This discrepancy suggests either selective preservation or overprinting of isotopic signals during sedimentation, potentially reflecting carbonate precipitation influenced by heterotrophic metabolism deeper in the water column or within the sediments.

These discrepancies may have important implications for lacustrine carbonate paleotemperature records, particularly in systems where microbial processes play a significant role in carbonate formation.

Sedimentology + Surface Processes

Filip Novak Using Three-Dimensional Techniques to Study Sedimentary Structures: Insights into the Paleocene-Eocene of Wyoming and Aeolian Deposits on Mars

Three-dimensional (3D) features of sedimentary outcrops can provide insights into the environments, hydrology, and tectonic settings in which the rocks formed. In river systems, one such feature are cross-sets, which preserve fluvial responses to environmental shifts. Measurements of the thicknesses and variation among these cross-sets can reveal changes in river behavior, such as flash flooding and channel migration. Although previous studies have collected cross-set measurements in the field, 3D modeling presents opportunities for the development of accessible, higher accuracy workflows to extract and verify measurements from digital reconstructions after fieldwork. Here, we introduce a technique to assess the shape, thickness, and variability of cross-sets (a method we can also apply to other structures in the sedimentary rock record) while correcting for modern weathering-related distortion. Our method leverages Structure from Motion (SfM) photogrammetry, which enables us to construct millimeter-scale 3D models of outcrops. We use these models to extract detailed measurements from outcrops that are otherwise challenging to quantify in the field, and revisit them virtually for further analysis. Due to the digital nature of our approach, we are able to adjust the resolution and type of measurement that we extract from each cross-set long after initial data collection. We present a case study from the Bighorn Basin of Wyoming, where we apply our technique to investigate how fluvial systems responded to increased temperatures and precipitation during the Paleocene-Eocene Thermal Maximum (PETM). We explore various hypotheses regarding the extent of change in river behavior before, during, and after the PETM, and provide additional insights into how the fluvial rock record preserves unsteady and steady flow regimes. Our results demonstrate that 3D modeling and data extracted using accessible workflows enable analyses that further our understanding of the rock record with enhanced precision and accuracy. Together, these analyses and workflows translate to robust and meaningful paleohydrologic and paleoenvironmental reconstructions, expanding and refining the interpretation of meter-scale outcrops on Earth and beyond.

Manuela Köpfli Spatial Variability of Critical Zone Processes

To better understand how the shallow subsurface responds to environmental forcing, we monitored a ~40 km transect spanning 1000 m of elevation and diverse soils and lithologies. Using continuous ground vibration measurements, we track temporal and spatial variations in near-surface conditions and compare them with weather records, river discharge, and soil-pit observations. The results highlight how hydrological processes shape both mountainous and agricultural landscapes, and point toward ways to improve water management and geohazard assessment.

Gabriel Santana The legacy of megaflood boulder deposition on river–valley form: Insights from high-resolution topography in the Eastern Himalaya

Topography is widely used to infer climatic and tectonic forcing in active mountain landscapes, where river incision and valley form reflect the balance among uplift, erosion, sediment supply, and water discharge. In many high-relief, rapidly-eroding regions, bedrock rivers are often interpreted using steady-state frameworks that relate channel form to drainage area, channel slope, and erodibility. However, in tectonically-active regions such as the Eastern Himalaya, episodic, extreme floods may drive rivers away from steady state and leave lasting signatures in channel and valley form. Megafloods (>10⁶ m³/s) have occurred repeatedly in the Eastern Himalaya, transporting and depositing large volumes of coarse sediment. Published geomorphic modeling in this region shows that megaflood-boulder deposits can inhibit vertical incision, steepen channels, and trigger meter-scale knickpoints along the main channel. However, it remains unclear whether the present-day landscape fits these predictions. Here we test whether reaches affected by megaflood-boulder deposits show systematic differences in channel form relative to nearby rivers without evidence of such events. Using high-resolution topographic data and previously mapped boulder deposits along the Lower Siang main channel, we quantify and compare channel steepness and knickpoint distribution between the megaflooded Yarlung–Siang River and adjacent rivers (Subansiri and Dibang) to assess how coarse sediment deposits relate to downstream changes in channel form. By linking the spatial distribution of megaflood-derived sediment to variations in channel and valley form, this work tests hypotheses associated with the lasting geomorphic effects beyond the flood event itself. Together, these observations highlight how sediment transport and storage associated with episodic, extreme floods can influence river processes, promote transient adjustment, and shape river–valley evolution in tectonically active mountain landscapes.

Bering Tse Inland limits of 1700 CE paleotsunami sand deposition and paleo-inundation extent at Lagoon Creek, California 

Lagoon Creek (41.6° N) is a rare location in southern Cascadia with well-preserved tsunami deposits from subduction zone earthquakes. This impounded coastal estuary forms a freshwater pond that sits 300m from the coast, and supports a freshwater marsh inland. Previous work at this site in 1998 identified these deposits as records of subduction zone-generated tsunamis. Our recent coring effort at Lagoon Creek is improving inundation estimates for the 1700 CE event. I present initial results from 80 shallow cores taken in the marsh during the 2025 field season.

We sampled sand deposits at every observation and collected cores from 16 sites for further analysis. The 1700CE sand horizon can be traced 1.1km inland, as a minimum inundation extent. The true inland limit of paleotsunami inundation is likely further, as sand deposits can be representative of 70-90% of total inundation (Abe et al., 2012). To determine a more accurate paleotsunami inundation limit, our current work is assessing other inundation evidence such as microfossils and geochemical tracers.  X-ray fluorescence with iTrax has a developing application in coastal paleoseismology (Giang et al., 2025), and we present initial results at this site.

Glaciology

Dominik Gräff Calving-induced submarine melting

Calving fronts are the nexus where atmospheric and oceanic forcings on the cryosphere condense. The dynamic processes acting at these fronts not only govern the evolution of tidewater glaciers but also exert a strong control on the stability of the Greenland Ice Sheet. Rapid changes in these processes driven by global warming, together with potential feedback mechanisms, may contribute to partial ice-sheet disintegration with profound regional and global environmental and socio-economic consequences.

One process expected to intensify under warming is iceberg calving, which can enhance submarine melting at glacier termini, thereby modifying the submerged ice-front geometry and preconditioning the ice front for further calving. To investigate this feedback mechanism, we analyze recordings from Distributed Acoustic and Temperature Sensing (DAS and DTS) acquired on a subsea fiber-optic cable deployed along the calving front of a marine-terminating glacier in Greenland. DTS observations reveal transient internal gravity waves generated by calving events, which we use to estimate the associated enhancement of submarine melt rates. Concurrent DAS measurements capture underwater acoustic noise, partly originating from the resonance of air bubbles entrained in glacier ice and released during melting. By jointly interpreting these observations, we aim to quantify the contribution of iceberg calving to enhanced submarine melting at calving fronts.

Liam Kirkpatrick Oldest-Ever Ice Core Water Isotope Record of Antarctic Ice Sheet Surface Temperature

The evolution of the East Antarctic Ice Sheet and Antarctic climate through the late Miocene and Pliocene (7 - 2.6 Ma) is understood to be complex. There is evidence of significant changes to ice sheet extent and regional temperature. However, current Antarctic proxy records through this time period are sparse, with poor spatial coverage and temporal resolution. Here we present the oldest ice core water isotope record of Antarctic temperature, from ice cores drilled in the Allan Hills blue ice area on the margins of the East Antarctic Ice Sheet. We improve on both the temporal extent and resolution of prior Allan Hills reconstructions. We also improve the interpretation of the d18O and deuterium excess record, through application of the Simple Water Isotope Model (Markle et al., 2022) modified to accurately represent Miocene and Pliocene climate. The result is a high-resolution record of both local temperature and moisture source temperature with robust uncertainty estimates. These data provide new insight into the surface elevation history of the ice sheet through this dynamic time period.

Marguerite Shaya Radar measurements in ice with steeply tilted layers

Interferometric phase-sensitive radar is becoming a standard glaciological technique for measuring the vertical deformation of internal layers in regions of simple ice flow. Interpretation of radar data becomes complicated, however, when englacial layering is not horizontal. We conducted experiments using an Autonomous phase-sensitive Radio Echo Sounder (ApRES) system at two sites in the Allan Hills, Antarctica, where steep layering (~28° and 68° from horizontal respectively) is well characterized through ice core measurements and shallow profiling radar. Tilting the radar setup in line with the layering results in stronger reflections. The range of reflectors remains mostly constant across different radar tilts, suggesting that ApRES measurements in areas of steep layering include strong off-nadir reflections. We combine inferences from the tilted ApRES experiments with simple models of scatterers in the ice to develop a framework for interpreting radar interferometry in areas of steep layering. 

Sophia Ludtke Projecting Future Changes in Northerly Winds and the Amundsen Sea Low

The West Antarctic Ice Sheet (WAIS) has been losing mass at an accelerated rate over the past two decades. A definitive anthropogenic attribution statement linking human forcing to mass loss in the Amundsen Sea region of Antarctica, however, has yet to be made. An interconnected chain of processes is hypothesized to link greenhouse-gas emissions to (1) high-latitude atmospheric circulation, (2) the intrusion of warm, wind-driven modified circumpolar deep water (CDW), and ultimately (3) ice-shelf retreat. Prior studies use ice-core-based paleoclimate reconstructions to extend the atmospheric record further back in time using data-assimilation methods, suggesting northerly winds may be responsible for simulated ocean warming in high-resolution regional ocean simulations. This project uses both forced and unforced (control) simulations from the CESM2 Large Ensemble and CMIP6 archives to isolate and evaluate anthropogenic signals in Amundsen Sea atmospheric dynamics. Specifically, we will quantify (i) changes in the magnitude (pressure minimum) and location of the Amundsen Sea Low (ASL) pressure system and (ii) regional wind-stress anomalies that modulate CDW transport pathways. By comparing trends in these metrics across forced and unforced model experiments, we aim to distinguish an externally forced circulation change signal from internal variability. 

Using a statistical detection and attribution framework, we will establish whether future shifts in the ASL and associated wind patterns exceed the range of natural variability. In doing so, we will clarify the mechanism by which atmospheric forcing drives ocean heat delivery to the West Antarctic, while strengthening the basis for statements linking human forcing to WAIS melt and resultant sea level rise.

Daniel Otto Temperature Lapse Rates on the Juneau Icefield: Initial Results

Models of glacier change commonly parameterize melt as being proportional to near-surface temperature. A standard approach is to downscale temperature from global climate model projections to the local topography using near-surface temperature lapse rates – the rate of temperature change with elevation. Theory predicts that lapse rates vary with atmospheric moisture: approximately -4 °C/km in wet maritime climates versus -10 °C/km in dry continental climates. Although widely used, the limitations of the lapse-rate parameterization for modeling glacier melt remain poorly understood, potentially introducing systematic biases in melt projections.

The Juneau Icefield spans the transition between the maritime climate of Southeast Alaska and the continental climate of northern British Columbia, presenting a unique natural experiment. We measured lapse rates across this maritime-continental climate transition to test whether theoretical lapse-rate predictions hold in glacier environments and identify factors controlling observed variability.

Preliminary analysis of temperature data collected during summer 2025 reveals mean lapse rates of approximately -2 °C/km — substantially shallower than typical values. Overall, maritime and continental lapse rates show a small but significant difference (< 0.5 °C/km), suggesting that glacier-specific processes, particularly katabatic winds, tend to override regional climate controls. The data also reveal temporal variability in lapse rates, including multi-day temperature inversions (positive lapse rates), which correspond to synoptic-scale weather patterns. This lapse rate variability correlates with observed periods of enhanced melt, demonstrating that local processes substantially modulate the relationship between regional temperature and glacier melt.

Tuesday, March 31st

Solid Earth Processes

Deven Loska Strontium Isotope Ratios as a Proxy for Fluid-Rock Interactions in the Protolith of Catalina Schist Metabasalts

Chemical compositions of subducted rocks influence how they will deform at depth, making it crucial to understand the degree to which fluid-rock interactions alter basalts in the oceanic crust prior to subduction. We investigate the degree of seafloor alteration of metabasalts in the Catalina Schist (Pimu’nga/Santa Catalina Island, California), which represent an ancient exposure of underplated oceanic crust resulting from the subduction of the Farallon plate under the North American plate during the Cretaceous. We analyzed whole-rock 87Sr/86Sr ratios of samples from the Epidote Blueschist unit of the Catalina Schist, characterized by epidote phenocrysts within a deformed fabric containing glaucophane and chlorite– minerals indicative of fluid flow and hydration. Initial Sr isotope ratios (calculated for 105-195 Ma) range from 0.702 to 0.705, with some samples shifted from a value indicative of unaltered mid-ocean ridge basalt (MORB; 87Sr/86Sr ~ 0.702) and towards a value indicative of Jurassic seawater (87Sr/86Sr ~ 0.708). Using mass balance calculations for a single-pass, open-system equilibrium reaction, we estimate minimum water/rock (W/R) ratios for the metabasaltic protoliths prior to subduction to range from 0.4 and 8, comparable to those of basalts in modern hydrothermal systems. However, major-element compositions of our samples suggest little modification away from an average MORB composition towards typical MORB seafloor alteration products. Thin-section analysis further reveals no significant variation in mineral assemblage or fabric development across samples with different estimated W/R ratios. The 87Sr/86Sr ratios and modelled W/R ratios indicate pre-subduction hydration of the basalts, likely serving as an important source of metamorphic fluids during subduction dehydration. The decoupling between Sr-isotopes, major-element compositions, and mineralogy suggests that either (1) seawater interactions were insufficient to alter major-element chemistry, or (2) the initial Sr isotope ratios were consistent among samples, with isotopic differences introduced by variable amounts of sedimentary-derived fluid input during subduction and/or retrograde metamorphism. Moreover, our results suggest that the magnitude of W/R alteration of the epidote blueschist protoliths prior to subduction was not large enough to result in significant differences in deformation style. By linking slab hydration to deformation textures, we provide insight into subduction zone processes that can be applied to similar rocks worldwide.

Christina Stuhl Investigating Major Element and Fluid Evolution in Metagraywackes From Seismogenic

to Sub-Arc Depths During Subduction

When considering the geochemical and physical behavior of a subducting slab, metapelites in the overriding sediment and MORB in the crust are most often modeled as the only rocks metamorphically evolving along the plate interface. While useful, metapelites do not representthe majority of sediment entering subduction zones at the trench or those subducting down to sub-arc depths. Instead, metagraywackes and their estimated protoliths – spanning a wide compositional range – occur in much greater volumes than other sedimentary inputs, particularly where deep-sea turbidite fans and trench sediment channels are active. These sediments are expected to significantly influence the behaviors of fluids where the subducting sediment layer is thickest. Despite their volumetric importance, greywackes are typically examined in a post- eruptive context or under high-temperature partial melting conditions related to arc volcanism, leaving their role in the fore-arc system underexplored. Principal component analysis (PCA) and PerpleX thermodynamic modelling are used to investigate greywacke behavior spanning from the subduction seismogenic zone past the sub-arc. PCA results indicate that modal evolution during subduction is strongly controlled by initial SiO₂, Al₂O₃, and CaO content. These compositional ranges exert a first order control on the abundance hydrous phases, most notably lawsonite, epidote, and micas that are predicted to be stable at various depths along the subduction paths. PerpleX modeling further suggests that the consistency of dominant stabilized phases across variable bulk compositions may indicate that greywackes are well suited to isolating the effects of slab temperatures on hydrous mineral stability, sediment dehydration, and deformation processes.

Francisco Reyes Do metamorphic dehydration reactions cause intraslab earthquakes in Cascadia?

The 2001 Nisqually 6.8 M w earthquake was the most destructive in Washington state history, nucleating at a depth of 51.8 km. Measured moment tensors indicate the earthquake was likely caused by the reactivation of a pre-existing fault in the subducting lithosphere. Assuming this fault was significantly hydrated when it formed, metamorphic dehydration and subsequent dehydration embrittlement could catalyze fault reactivation. I model the metamorphic evolution of the subducting slab using the Gibbs energy minimization software PerpleX to predict the pressure-temperature conditions of various dehydration reactions for several possible slab compositions and slab thermal paths. I argue that this and other Cascadia intraslab earthquakes occur due to localized fluid-releasing metamorphic dehydration reactions leading to dehydration embrittlement driven reactivation of pre-existing slab bending faults. This dehydration driven seismicity has been evidenced to occur in other warm subduction zones (e.g., 2017 Puebla- Morelos earthquake) and may be applicable to other similar subduction zones (e.g., Central American subduction zone, Sunda subduction zone).

Anna Pearson Modeling Framework for Surface Loads in the Postglacial Puget Sound

This study defines a modeling framework developed to constrain the response of the Puget Sound region to glacial and sea level loading, with emphasis on how the Earth structure and surface load can be parameterized and implemented in a model. The long-term goal is to focus on the impact of time-dependent stress loads on crustal faults, but here we focus on the construction and implementation of the modeling approach. We parameterize the Earth’s viscoelastic structure with a layered crust and mantle, including the subducting Juan de Fuca slab and associated mantle wedge. We discuss the choices underlying this earth structure, including significant uncertainty in the layer thickness and viscosity. The surface load is defined based on glacial advance and retreat and subsequent changes in relative sea level. Ice loading is derived from a combination of ice thickness estimates for the Cordilleran Ice Sheet and Puget lobe, as well as additional estimates constraining the time history. Water loading incorporates relative sea-level histories estimated from sea-level index points in the last 11ka, corrected for absolute changes in sea level. Alternate assumptions about load geometry and temporal evolution are explored. This flexible framework enables systematic evaluation of uncertainty in Earth structure and surface loading histories in the Puget Sound region, with importance for future work focused on linking surface loads to fault mechanics and regional seismic hazard.

Veronica Gaete Elgueta Fiber Sensing at the Puyehue-Cordón Caulle Volcanic Complex

The remarkable 2011 eruption at the PCVCC produced one of the fastest recorded laccolith uplifts, rising 50 meters in a matter of weeks. Because this uplift occurred in a structurally weak zone rather than directly above the central magma body, the site offers an ideal natural laboratory for investigating shallow magma intrusion, laccolith geometry, and the interplay between magmatic and hydrothermal processes.

To image the shallow subsurface at the 2011 vent site, we propose deploying ~3 km of fiber optic cable connected, enabling continuous Distributed Acoustic Sensing (DAS) recordings for as long as permitted by logistical constraints (two weeks nominal). Ambient noise interferometry with these data will allow us to recover Rayleigh and Love wave velocity anomalies at depths of 200–400 m.

Also, we anticipate discriminating among different tremor types associated with hydrothermal and tectonic sources and relating these to processes to underlying structures.

Geologic Hazards + Society

Chloe Anderson Deep Si: A Brief History of Seattle's Favorite Mountain

While most know Mt. Si as a peaceful hiking destination, its geology weaves a tale of great upheaval. From the melting of ancient seafloor magmas to the destructive advance of Pleistocene glaciers, the rocks of Mt. Si reveal the tumultuous origin of the Pacific Northwest.

Jess Ghent TBA

Abstract.

Julia Grossman, Deven Loska, Anna Frank, and Nissa Stupakoff Cascadia Culture And geoScience Exchange (CCASE): Building Community Resilience to Cascadia Geohazards and Fostering STEM Identities of Indigenous Youth

Communities along the coast of Washington and Oregon in the Pacific Northwest are at risk of large Cascadia subduction zone earthquakes and subsequent tsunamis.  Indigenous communities are particularly vulnerable to high intensity ground shaking and tsunamis from such major megathrust events.  In recent years, tribal schools in the tsunami inundation zone have begun relocating to higher ground.  However, this is not enough to protect entire communities from ground shaking, inundation and landsliding coseismic hazards.  This vulnerability of Native communities demonstrates the importance of strengthening resilience to geohazards and of supporting indigenous students in Earth Science and STEM fields.

Cascadia Culture And geoScience Exchange (CCASE) is a grassroots initiative spearheaded by graduate and undergraduate students at the University of Washington (UW).  CCASE strives to increase coastal community resilience to geohazards through long-lasting and impactful educational partnerships with rural and tribal K-12 schools at risk of Cascadia earthquakes and tsunamis.  CCASE’s Quileute (Kʷòʔlíyot’) program at Quileute Tribal School in La Push, WA, is currently in its fourth year, and CCASE’s Makah (Qʷidiččaʔa·tx̌) program at Neah Bay High School in Neah Bay, WA, is in its second year.

Based on UW’s Riverways Education Partnerships program, CCASE team members develop week-long geohazards curricula that they then teach during UW’s spring break.  Hands-on lessons integrate geoscience and indigenous knowledge, with local field trips and guest lectures from Elders providing vital place-based learning.  By centering indigenous culture, histories and lived experiences, CCASE aims to empower rural and tribal students to see themselves as Earth Scientists and to pursue STEM after high school.

Additionally, during spring break week and on site visits throughout the school year, team members learn from students, partner teachers and community members who graciously share their cultural traditions, languages, histories and traditional knowledge.  CCASE team members also mentor select high school students through CCASE’s year-long paid internship program, which aims to create a pathway for indigenous students into the field of Earth Science.

Chapin Reece, Rohan Batten, Asher Haywood, Estella Medford, Tanner Swanson, Brandon Heald GeoClub Spring Break Trip 2026

The University of Washington's GeoClub recounts and reflects upon this year's spring break trip through the Oregon Coast and up the Columbia River. This investigation, taking place from March 21st to March 25th, will expose undergraduates to solid earth & surface processes that have shaped local geology and topography. From subduction and the accretion of various terrains at the western edge of North America to the Columbia flood basalts, the region surrounding the Columbia River provides a key window for geology students to absorb a myriad of earth processes in a relatively small geographic area proximal to the university. 

Upgoer 5s

Trent Thomas Fire World

Henry Yuan Studying the forms of tiny rocks to see how they moved long ago

Jess Ghent TBA

Lucy Helms Do animals and not animals build the same kind of homes under water through time?

David Caro High land and rain change through time

Through time, land and wet and dry change together. One clear case of this change is the build and grow of high land. When wet air moves toward high land, the air is forced to go up. As the air goes up, it becomes cold and rain falls. After the air goes over the high land, it holds less water, and the land on the other side becomes more dry.

The rain that falls before and after high land is not the same. The water in the rain shows change on how much rain has already fallen and how high the land is. These change can be found by looking at rain water today. When rain falls on land, its sign can stay in ground and rock. Over a long time, these sign can stay in old rock.

By looking at rain sign in old rock, we can learn how high land began and how it grew through time. Knowing how rain change as land becomes high helps us tell different time in the build of high land. This work helps us better understand how land change drive wet and dry over the past.

Poster Session 

Scott Chang Neural Network–Based Geophysical Inference of Europa’s Ocean Composition

A main goal of NASA’s Europa Clipper and ESA’s Juice missions is to understand the habitability of Jupiter’s moon Europa. These missions will return an unprecedented volume and quality of gravity, magnetic sounding, and radar data to probe Europa’s interior structure and physical properties. Recent advances in self-consistent forward modeling with PlanetProfile v3 and improved computational infrastructure now make it possible to apply geophysical inference (GI) to characterize Europa’s ocean salinity—the aqueous composition of dissolved ions and solutes and resulting bulk concentration. By coupling GI with geochemical constraints, our approach enables understanding the subsurface geochemical conditions of Europa from geophysical observables. 

Extending GI to develop robust constraints on Europa’s ocean composition requires considering the broader space of possible aqueous chemistry based on different scenarios for Europa’s formation, subsequent thermal-orbital evolution, and the evolution of its ocean. Current state-of-the-art Bayesian methods like Markov Chain Monte Carlo (MCMC) are impractical for developing such constraints due to the substantial computational costs associated with the exploration of this high-dimensional parameter space. Thus, we are developing a neural network-based approach to robustly infer the ocean chemistry of Europa—and by extension other ocean worlds—from geophysical measurements. 

We will first present constraints on Europa’s redox state assuming the bulk-silicate model for Europa. We also will consider the implications of such constraints for inferring the possible ranges of affinity for metabolisms such as methanogenesis. Finally, we will discuss preliminary outlooks for constraining Europa’s salinity by integrating GI with the full suite of Europa Clipper’s compositional investigations, which will enhance the ability to infer the chemistry of Europa’s ocean and thus to understand its potential for life.

Charles Fleming Developing a novel high-pressure, high-temperature experimental chamber to study Venus’ evolution

Venus’s climate evolution is largely unknown. With a current surface temperature of ~460°C, pressures near 98 bar, and a dense CO2 atmosphere, direct observations of the surface are difficult to obtain.  Until future missions to Venus are launched, experimental constraints are critical to understanding its geologic and atmospheric evolution. Here, we develop a novel high-pressure, high-temperature planetary chamber to simulate both early and modern Venus conditions. 

Methods: We have designed a novel experimental apparatus to different evolutionary scenarios on Venus. This is a custom-built nickel-chromium chamber allowing us to test high oxygen atmospheres on Venus. My contribution focuses on construction and safe operation of a planetary simulation chamber. Our experiments will exposure tholeiitic basalt samples to O2-CO2 mixtures under simulated modern and post accretion Venus conditions (100-300 bar; 700-900 K) for durations of up to three weeks. Following exposure, samples are analyzed to measure the critical kinetic constraints, for example the oxidative diffusion coefficient, cation migration in basalt, and surface weathering rates. 

Expected Outcomes: We are expecting to measure kinetic and thermodynamic constraints representing the Venusian surface. These constraints paired with geochemical modeling will better our understanding of Venus’s geochemical evolution. The results from these planetary chambers will ultimately help investigate if Venus was ever habitable in the past.

Kyle Nash Paleoclimate and Human Migration: Developing a Geochemical Record of Lucayan Settlement from Coral Abrader Tools

Testing hypotheses that draw causal links between human activity and climate change require robust, well-dated records of both past human behavior and environmental conditions. Archeological artefacts preserved on the Turks & Caicos Islands (TCI) provide a unique opportunity to study the intersection of these areas. The TCI are low-lying carbonate islands at the southeastern terminus of the Lucayan archipelago in the north Atlantic Ocean. Indigenous Lucayan Taino settlement of the TCI spans the 8th-16th centuries of the Common Era and includes multiple waves of migration. Initial migration into the TCI from the Greater Antilles occurred in the 8th century AD and is hypothesized to relate to wetter, warmer conditions during the Medieval Climate Anomaly.

This presentation details our team’s work to develop a chronology of Lucayan settlement using U-Th dating techniques on coral abrader tools that were harvested from living corals by Lucayan divers. Because their geochemical composition reflects the chemistry and temperature of the seawater in which they grew, these corals are unique archives of both Lucayan settlement history and regional paleoclimate. We will give an update on our efforts to develop methods to precisely measure U and Th isotope abundances in carbonates at The University of Washington. Future goals of this project are to 1) generate U-Th chronologies for our suite of coral samples, 2) apply paleoclimate proxies such as the δ18O and clumped isotope paleothermometers to develop records of sea-surface temperature and precipitation, and 3) leverage this paleoclimate data to assess regional climate models and study the impact of climactic shifts on Lucayan settlement of the TCI.

Sophia Robillard Formation Processes and Environments of Miocene Lacustrine Carbonates: Petrographic and Isotopic Implications for Paleoclimate Reconstruction on the Colorado Plateau

Lacustrine carbonates are valuable sedimentary archives of paleoenvironmental conditions such as climate and biogeochemical cycles. However, interpretations can be complicated by physical, chemical, and biological influences on carbonate formation, deposition, and post-depositional alteration. Here, we investigate the origins and isotopic variability of fine-grained carbonates in well-preserved Miocene lacustrine marls from the Bidahochi Formation of the Colorado Plateau. Using detailed petrography alongside δ¹³C, δ¹⁸O, and dual clumped-isotope (Δ47, Δ48) thermometry, we assess how biological processes and early diagenesis may affect geochemical data for paleoenvironment reconstructions. 

We selected fine-grained carbonate samples for isotopic analyses, each lacking diagnostic features in hand sample but exhibiting textural diversity at the microscale. Petrographic analysis revealed abundant micritic cement, carbonate mud, peloids, and cyanobacterial filaments. Micrite is found in fine-grained lacustrine carbonate rocks and is proposed in recent work to form through both inorganic and biogenic mechanisms. Although some observed micrite could have precipitated in the water column, the presence of peloids and biologically derived components suggests significant carbonate precipitation at or below the water-sediment interface and in pore spaces after deposition. Carbonates that precipitated in lake-bottom environments may record different environmental conditions from those of the lake surface water and air temperatures. Understanding these impacts on carbonate proxy measurements is crucial for accurate interpretations of paleoenvironments from stable isotope records. The presence of micrite and biologically derived structures motivated us to investigate these samples for biologically mediated origins that may cause carbonate to precipitate out of isotopic equilibrium as shown by Δ47-Δ48 data and alter paleoclimate and hydrologic interpretations of this basin.

Jillian Ruby Evaluating methods for removal of organic contaminants in carbonate clumped isotope thermometry: implications for lacustrine paleoenvironmental reconstructions

Paleoenvironmental reconstructions are essential to understanding the history of our climate. Clumped isotope analysis is a valuable tool to study these environments. It uses mass spectrometry of carbonate minerals, which can be correlated with specific temperatures of formation and give insight to environmental conditions when they form in equilibrium. This is well recorded in lacustrine environments, as the carbonate deposits are sensitive to changes in the local climate, tectonic setting, and hydrological conditions. When performing clumped isotope analysis, carbonates are dissolved to release CO₂. The bonding of heavy isotopes within CO₂ are referred to as clumped isotopes, and their relative abundance in a sample is dependent on the temperature they formed at. The heavy ¹³C -¹⁸O bonds in the molecule are the most common, and its ratio in the sample is referred to as Δ47. In recent literature there has been a shift to measuring Δ47 values along with Δ48, with preferential ¹⁸O - ¹⁸O clumping. The ability to compare Δ47 to Δ48 values using this method is essential in understanding reaction kinetics, if rocks formed at equilibrium or disequilibrium. This is a new, cutting edge method that we have performed with great precision. Within lacustrine carbonate samples, there are organic contaminants that interfere with the CO₂ digestion process. Thus, they must be removed before we can perform isotope analyses. There are varying methods described in past literature to do this using acidic H₂O₂, alkaline H₂O₂, NaOCl, and alternative temperature-based methods. H₂O₂ is commonly used for these methods in bulk isotope analysis, where the δ¹³C and δ¹⁸O ratios are studied, however, it has not been examined for its impacts on clumped isotope analyses. Hence, this study investigates the various ways in which one can remove organics from carbonates through the lens of clumped isotope analysis, making more precise and accurate measurements for paleoclimate reconstructions.

Abby Waller A preliminary faunal analysis of insectivorans from the latest Torrejonian of southeastern Montana

The Paleocene epoch (66-56 million years ago [Ma]) is characterized by rapid diversification of mammals after the mass extinction that wiped out non-avian dinosaurs. Although considerable work has been done on mammalian diversity in the early and late Paleocene of North America, the mid-Paleocene (ca. 63-58 Ma) is relatively understudied. Preliminary reports from continental-scale compilations indicate that mammalian generic richness peaked initially and then steeply declined after the Torrejonian-Tiffanian boundary (~61 Ma). More granular study of faunal composition during the latest Torrejonian (To3) is critical.

Among the To3 mammalian faunas are early insectivorans. This collection of taxa, which are distinguished by their shared dental features related to insectivory, represents a variety of taxonomic orders during the mid-Paleocene, including Leptictida, Cimolesta, and Eulipotyphla. Efforts to document additional specimens and taxa are vital to better understand their faunal composition during this understudied time interval. Southeastern Montana has a variety of fossil localities, two of which have been provisionally attributed to the To3 interval: Mehling Site and Medicine Rocks I-III. These sites offer an abundance of well-preserved mammal specimens, ~80% of which are eutherians and ~20% allotherians. Housed at the Carter County Museum (CCM) in Ekalaka, MT, and the Yale Peabody Museum (YPM) in New Haven, CT, are collections of hundreds of specimens, most of which are isolated teeth, but include a number of well-preserved jaws. Among these specimens are some teeth identified as insectivorans representing all orders known to exist in this interval. Here we present a preliminary faunal analysis of insectivorans recovered from the To3 localities in Carter County. Future work will entail a species-level faunal list of insectivorans during the latest Torrejonian and the time periods bounding it to assess changes in insectivoran diversity during the mid-Paleocene.

Shannon Jones Detrital Zircon Age and Geochemical Constraints on Cambrian Sandstones in Western Newfoundland

This study presents a new record of sediment provenance in Cambrian (Dyeran to Steptoean) strata in western Newfoundland using detrital zircons (DZs) from the Hawke Bay, March Point, and Petit Jardin Formations. U-Pb dates and trace and rare earth element (TREE) ratios were measured using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. These data, together with sedimentological and stratigraphic information, are used to test the hypothesis that the provenance of sediment here changed over this interval, and to compare provenance across the Laurentian passive margins. Analysis of TREE concentrations and ratios, including Nb, Ta, Th, U, Yb, P, Gd, and Y is used to investigate potential differences in sources between grains of the same age population.

Our data show no evidence for a temporal shift in sediment provenance in western Newfoundland based on U-Pb dates alone. Samples are dominated by Archean, Paleoproterozoic, and Grenville-aged sources, and age populations are highly consistent between samples from the Hawke Bay, March Point, and Petit Jardin formations. Previous studies along the eastern Laurentian margin support these findings, and further characterize the development of this passive margin and the opening of the Iapetus Ocean and the Humber seaway.

These data contrast with DZ spectra from middle to late Cambrian sediment deposited on the western and northern margins of Laurentia. Samples from these margins often show two distinct provenance profiles: one dominated by Archean and Paleoproterozoic-aged sources and another composed of significant Grenville-aged input. Spatial and temporal variations between these two signatures are interpreted as reflecting different sediment sources, isolation of some basins from Grenville-aged input by uplift of the Transcontinental Arch, and/or changes in the inundation of Laurentia during the Sauk sequences of the Cambrian Period. We integrate and compare these diverse records to gain a better understanding of Laurentian sediment sources and barriers to sediment dispersal during the Cambrian Period.

Brooke Santos Evidence for a late-Holocene shift in Nooksack River routing and what it means for avulsion risk today

The Nooksack River in northern Washington is at risk of avulsing north toward the Fraser River in Canada, a course change that would reconfigure flood hazards and threaten communities across the lower Sumas Valley. Existing evidence for past routing is substantial but fragmented across published literature and gray sources; here we consolidate these records and introduce new geomorphic metrics and topographic analysis to refine avulsion interpretations. We constrain the timing and context of past course changes by integrating geomorphic evidence, delta progradation distance, stratigraphic records, radiocarbon dates, sediment provenance, fish genetics, Tribal oral histories, and anthropological and archaeological interpretations. Delta progradation distance and shell midden ages indicate sustained sediment delivery to Bellingham Bay in the late Holocene, but the limited present-day delta size is difficult to reconcile with continuous occupation of the modern outlet over the midden-dated interval, implying earlier routing was directed elsewhere. The low drainage divide and preserved remnant channel meanders through the Sumas Valley document an alternative pathway that is hydraulically and topographically feasible. Stratigraphic relationships and provenance signals record relict sediment pathways and channel positions consistent with Holocene reorganization. Mt. Baker andesite deposits associated with northward flow routing overlie the Mount Mazama tephra, indicating that this flow path was active after tephra emplacement and persisted into the late Holocene. Tribal oral histories and regional linguistic affinities provide additional qualitative context for long-term connectivity across the Fraser lowland, complementing the physical record. Together, these independent datasets support the hypothesis that the Nooksack flowed north through the Sumas Valley for much of the Holocene and avulsed to its modern course in the late Holocene. We interpret this behavior within a threshold framework in which long-term preconditioning increases the relative advantage of an alternate route, and discrete triggers push the system past an avulsion threshold. Candidate triggers include extreme floods, landslide- driven sediment pulses, Mount Baker lahars, fault-induced knickpoint propagation, and large wood jams capable of blocking flow and promoting overbank diversion. By narrowing the avulsion window and prioritizing testable triggers, this synthesis guides fieldwork to identify diagnostic deposits and improves the basis for anticipating future avulsion hazards in the Nooksack–Sumas lowland.

Winnie Fan Development of high precision analysis of stable Ce-Eu isotopes

Cerium (Ce) and europium (Eu) are redox-sensitive rare earth elements (REEs), and their isotopic compositions could potentially be powerful tracers of redox-controlled processes in geological systems. Studies on Ce-Eu isotopes remain scarce due to the analytical challenge. Here, we present progress on developing high-precision analytical method of Ce-Eu isotopes using solution-nebulization MC-ICP-MS at the UW Non-Traditional Isotope Laboratory.

Catie Zeiger Developing a Terahertz-Raman Spectral Mineralogical Database For Use in the Geosciences 

Raman spectroscopy is an important and increasingly common analytical technique with applications in the fields of mineralogy, crystallography, geochemistry, and planetary mineralogy. Terahertz-Raman (THz-Raman) spectroscopy addresses a major pitfall of typical (i.e., non-THz) Raman by enabling investigation of low-energy lattice vibrational modes; thus, it provides both the molecular and structural fingerprint of the mineral it is conducted on. Despite the implications of THz-Raman for discerning the pressure-temperature conditions under which mineral polymorphs have formed, a comprehensive database of mineralogical THz-Raman spectral data does not currently exist.

By cataloguing and conducting THz-Raman spectroscopy on an extensive mineral collection, we seek to fill gaps in the literature and compile a publicly available, searchable database for use by the geoscience community. Initial spectra of the most common minerals on Earth have been collected to enable development of a preliminary database for publication, to be expanded to ultimately represent all mineral classes. This work will encourage the development of THz-Raman methods in the geosciences by facilitating ease of data analysis for researchers spanning many disciplines.

Claire Jensen Investigating Seasonal Glacier Fluctuations in Northeast Greenland Using Deep Learning and Explainable Artificial Intelligence

The Greenland Ice Sheet is losing mass due, in part, to the recent speedup of many of its outlet glaciers, including Zachariæ Isstrøm (ZI), a large outlet glacier in the northeast region of the ice sheet. Not only does ZI play an important role in the ice sheet’s surface mass balance, but it also exhibits marked seasonal variability, observed in both glacier flow speeds and the terminus position. Compared to its neighbor Nioghalvfjerdsfjorden (79N), ZI does not have a floating ice tongue and is predicted to retreat much faster despite being subject to similar environmental forcings. Recently, studies examining a small number of large outlet glaciers have also linked the formation, build-up, and subsequent break-up of proglacial mélange to seasonal variability through its impact on the timing of glacier advance and retreat. Still, the relative impact of mélange and other variables, such as terminus position and meltwater runoff, on glacier flow and the extent to which they propagate further upstream remains unclear. Here, I train machine learning models to characterize the seasonal patterns of glacier flow and retreat at ZI and 79N, aiming to determine how meltwater, mélange, and terminus position drive changes in ice velocity and gain insight into the glaciers’ potential future changes. I then use explainable artificial intelligence techniques to reveal the reasoning behind the models' predictions to provide a deeper understanding of how glacier sensitivity (and thus, ice mass loss) to environmental conditions evolves over time, particularly in the event of ice tongue collapse as observed at ZI, and to expand our knowledge of two of the largest and most significant Greenland outlet glaciers.

Sofia Suhinin Investigating the Statistical Structure of Glacier Calving of Jakobshavn Isbræ, Greenland

The Greenland Ice Sheet covers nearly 80% of the country’s landmass, making it a major contributor to global sea level rise; complete melting would raise global sea levels by an estimated 7.4 meters. Between 1992 and 2018, Greenland experienced a negative mass balance, with ablation losses exceeding accumulation gains. Much of this can be attributed to calving, an ablative process in which ice breaks off from a glacier terminus. Despite its importance, calving remains one of the least well-parameterized components of mass balance, so improving our understanding of calving could refine the overall parameterization in larger-scale ice-sheet models. 

Here, we will investigate the statistical structure of glacier calving at Jakobshavn Isbrae using a satellite-derived calving time series. We believe that calving exhibits a characteristic statistical structure in which small events occur more frequently than large events, and events cluster in time, such that individual calving events may appear random while the overall behavior follows a recognizable pattern. This behavior is analogous to other natural systems, such as earthquakes, characterised by event clustering and scale-dependent magnitudes, suggesting that calving statistics may be described by a mixture of distributions.

​Using satellite-derived terminus positions and surface velocities, we will construct a calving time series to analyse the frequency, magnitude, and temporal clustering of calving events. We will explore whether the observed calving behaviour is characteristic of a mixture of statistical distributions that capture both event-size variability and temporal dependence, thereby creating a glacier calving time series for Jakobshavn Isbrae. Ultimately, this work aims to provide a simple statistically grounded framework for describing calving, with implications for improving the representation of calving  in ice-sheet models.

Josephine Anderson Finding Hidden Faults in the Chuckanut Formation (Whatcom County)

The Chuckanut Formation is an Eocene-aged fluvial sedimentary formation near Bellingham, Washington. The formation underwent significant SW-NE contraction due to the accretion of Siletzia from about 52-48 Ma. While deformation structures like faults and a syncline-anticline pair are observable in remote sensing imagery, the extent of the contraction remains unquantified. For this investigation, I used the Geologic Map Data Extractor (GMDE) to map bedding surfaces within the formation on a LiDAR map of the region. I used GMDE tools to find strikes and dips, then created a downplunge projection to illustrate the patterns of folding and faulting within the formation. I used this projection to locate hidden faults and estimate the direction and minimum total extent of the shortening experienced by the formation (around 30%), which helps us better understand the tectonic history of the area.

Will Dienstfrey Imaging the Sub-Sea Subsurface with Distributed Acoustic Sensing

For decades, arrays of traditional seismic instruments have been used for tomography studies, illuminating material heterogeneity in the subsurface through differences in spatially-resolved seismic wave speed. Historically, these studies have been largely constrained to onshore environments due to the challenges posed by installing dense ocean-bottom arrays. Distributed acoustic sensing (DAS) has revolutionized the world of marine sensing, transforming pre-installed ocean-bottom fiber optic cables into dense arrays of strain sensors that provide observations at meter-scale sensor spacing over ~100 km total distance. With these two advantages – ease of deployment and sensor density – DAS has opened the door to a new age of tomography studies. In this proposed poster we present findings from an ambient noise tomography study done with DAS observations of Scholte waves on the Whidbey submarine fiber optic cable in the Puget Sound. We use Markov Chain Monte Carlo (MCMC)  analysis to determine the sensitivity of subsurface velocity structure to layer count and thickness. Finally, we demonstrate how the dense station spacing can be leveraged to create a depth-dependent resolution scheme for the dispersion  curve to velocity inversion problem. This work highlights the numerous advantages that DAS observations provide, and the value performing these types of offshore observational studies.

Michael Hemmett Shear-Wave Splitting Reveals Stress Evolution Across the 2015 Eruption at Axial Seamount

Axial Seamount is a hotspot-influenced submarine volcano in the Northeast Pacific Ocean that lies at the intersection of the Juan de Fuca mid-ocean ridge and the Cobb-Eickelberg seamount chain. Its summit is characterized by a 100-m-deep caldera measuring 9 x 3 km3 which has hosted three significant eruptions in the past three decades. Since late 2014, the Ocean Observatories Initiative Regional Cabled Array has supported a real time network that includes bottom pressure gauges and a 7-station seismic network. The geophysical instruments recorded the subsidence and seismic crisis associated with a volcanic eruption in 2015 and subsequent increasing rates of seismicity as the volcano re-inflates through the present day. At volcanoes, shear-wave splitting measurements, specifically the fast polarization orientation and splitting time, are sensitive to microfractures.

Building on unpublished work by Christian Baillard, we are implementing a procedure to analyze more than 240,000 earthquakes in a deep learning-enhanced earthquake catalog for splitting parameters with thorough replication of the previous work and adaptation to more recent open-source software.  Seismic waveforms are first processed to select events with  a P-wave rectilinearity > 0.7, angle of incidence < 30°, and S-wave signal-to-noise ratio > 2.0 to ensure clean events with S-wave motion in one plane. Shear-wave splitting is performed with the SWSPy package. This method rotates the three-component seismometer of the S-wave window into the transverse plane and inverts the splitting operator to find measurements of the splitting parameters. This is performed across many S-wave windows with the results clustered to find measurements that are robust. The goal of this study is to interpret splitting parameters in terms of crustal anisotropy and stress evolution over a volcanic cycle and determine whether shear-wave splitting provides a useful precursory signal in concert with other seismic observations.

Sophia Nahas The Lasting Effects of Megafloods on River-Valley Width in the Eastern Himalaya

Bedrock rivers are commonly used to investigate landscape disequilibrium, as they record topographic responses to climate and tectonics. In tectonically-active mountain regions, river form reflects a balance among rock uplift, erosion, water discharge, and sediment supply. Disturbances to this balance provide a measure of disequilibrium and are central to understanding the evolution of mountain landscapes. The Eastern Himalaya is one of the most tectonically-active regions, with a long history of extreme flood disturbances. During the Quaternary, the Yarlung–Siang River recorded episodic megafloods (>106 m3/s) triggered by catastrophic glacial-lake failures. Previous work in this region shows that megafloods mobilize sediment from fine sands to coarse boulders, producing intense erosion and widespread deposition controlled by valley-topography. Published geomorphic modeling further suggests that megaflood deposits alter channel roughness and promote bed armoring with long-term impacts on channel form and processes; however, because these models hold channel width constant, their implications for channel and valley width in real landscapes remain unclear. Here we test whether mapped outburst-flood deposits are associated with downstream variations in channel and valley width, using valley-width measurements at flood-relevant inundation depths to evaluate topographic controls on flood dynamics and sediment availability. Bankfull channel and valley widths are measured from Google Earth imagery and compared across reaches with coarse and fine flood deposits. If outburst flood deposition leaves lasting signatures on the landscape, we expect channel and valley width to vary more in areas with preserved flood deposits. This would indicate that megafloods influence channel form and processes not only through intense erosion during the event, but also by reorganizing sediment in ways that persist long after deposition, leaving lasting effects on the channel and valley width.

Jewel Wass de Czege Constraining the recorded P-T path of The Exhumed Blueschist-Eclogite unit of Sifnos Greece: Revisiting an Incomplete Origin Story 

Subduction zones host megathrust earthquakes and arc volcanism, processes influenced by rheological changes in subducting slabs. As hydrated basaltic oceanic crust is buried and metamorphosed, it transforms from blueschist to eclogite facies. This transition is  associated with dehydration reactions that release fluids. These reactions alter strength and influence the subduction interface rheologic behavior with implications for these geohazards. The exact depth where lithologic transitions occur is influenced by the bulk composition of a given rock and the pressure-temperature (P-T) path it takes. To understand the significance of this transformation, we must know where it occurs.  

The exhumed Cycladic Blueschist Unit (CBU) at Vroulidia Beach, Sifnos Island, Greece  was chosen for our study because it exposes well preserved m-scale intercalated blueschist and eclogite lithologies. Previous work suggests bulk compositional differences between eclogites and blueschist is evidence for different protoliths at identical peak P-T condition resulting in separate metamorphic facies. However, our new geochemical analysis of intimately-intermingled blueschist and eclogite samples show nearly identical bulk compositions, challenging these previous interpretations of P-T conditions recorded by each of these facies within the CBU on Sifnos. 

We combined bulk rock geochemical data, detailed petrography, electron microprobe mineral compositions, and thermobarometry to establish the (1) original protoliths and (2) equilibrium conditions of our  blueschists and eclogites. Applying garnet-phengite-omphacite thermobarometry to matrix and inclusion assemblages with textural evidence for quartz-after-coesite yields constraints on garnet growth to temperatures from ~430–560°C and a peak pressure of ~2 Gpa. We refine pressure estimates along this prograde path during garnet growth using Raman-spectroscopy based Quartz-in-garnet barometry. Analyzing inclusions and zoning profiles captures distinct metamorphic stages from prograde to peak eclogite-facies conditions to retrogression under blueschist-facies conditions. Our data suggests the examined blueschist-eclogite transition on Sifnos represents a coherent section of oceanic crust derived from a calc-alkaline basaltic protolith, with retrograde overprinting of earlier eclogites by fluid interactions during the early stages of exhumation. This is supported by preserved high-pressure mineral inclusions (e.g., omphacite) in garnet cores within the blueschist samples, and compositional shifts between glaucophane in the matrix and in garnet inclusions. Due to the CBU’s rich history of exhumation and retrogression, our work highlights the importance of a detailed analysis to establish peak P-T conditions.