Petrology, Structure, and Tectonics (9:30am - 11:30am):
William Hoover Subduction interface talc controlled by Mg loss, not Si gain: Insights from Mg isotopes
Talc-rich metasomatic rocks in subduction interface shear zones profoundly influence seismicity and arc magmatism, but the reactions responsible for their formation remain controversial. Magnesium isotope compositions of subduction interface rocks from the Catalina Schist (California) record Mg exchange from ultramafic to crustal rocks. Preferential loss of isotopically light Mg from serpentinite produces isotopically heavy talc-rich metasomatic rocks. Addition of this isotopically light Mg to adjacent crustal rocks from the slab produces actinolite- and chlorite-rich metasomatic rocks that are isotopically lighter than their protoliths. Ca addition to ultramafic- and crust-derived metasomatic rocks is decoupled from this local Mg exchange and reflects a contribution from infiltration of metabasalt-derived fluid from the downgoing slab. Talc-rich rocks formed by passive enrichment of Si in serpentinite during Mg loss. This suggests that talc can form in subduction zones independent of diffusive or advective Si metasomatism, and that talc is prevalent along the interface from mantle wedge corner to sub-arc wherever ultramafic material is in contact with a significant Mg sink. Talc hosts slow slip events, modifies interface rheology and influences arc magmatism – considering talc and other metasomatic products is imperative for robust models of modern subduction zones.
Anna Ledeczi Investigating seismogenic zone processes via an exhumed Cascadia paleo-megathrust fault in the Olympic subduction complex
At the Cascadia Subduction Zone, the Olympic Subduction Complex (OSC) exposed in the central Olympic Mountains represents an exhumed subaerial analog to the modern Cascadia accretionary wedge offshore and to clastic-sediment-dominated wedges in general. Based on published metamorphic grade and thermochronology-based exhumation history, it is thought to have accreted by underplating at seismogenic zone depths of approximately 20 km. The OSC consists of broken formation and mélange made up of Eocene to Miocene age marine sandstones and mudstones. We hypothesize that the OSC was accreted in discrete fault-bounded packages and that strain was strongly partitioned between the finer and coarser-grained end members of the material. We document a 500m thick zone of scaly block-in-matrix mélange rocks, containing an anastomosing system of 10 major fault strands each hosting discrete faults within them, which we interpret as a newly-discovered example of an exhumed paleosubduction interface within the Olympic Mountains, the first of its kind from the modern Cascadia Subduction Zone. Our study characterizes the scaly fabric of this fault zone from macroscopic to microscopic scale through methods such as detailed geologic field mapping, outcrop photogrammetry, optical microscopy, and scanning electron microscopy. We investigate lithology, bulk strain, and evidence for deformation mechanisms, discriminating between discrete accretion-related fault-bounded packages versus spatially-continuous deformation and pervasive shearing. Grain-scale microstructures observed in deformed fault zone rocks reveal deformation mechanisms in action near the subduction interface, helping identify how seismogenic and accretionary processes operate. Raman spectroscopy of carbonaceous material refines peak burial temperatures of the OSC and sheds light on the path of these rocks through the accretionary wedge. Because of its remote location within Olympic National Park, the OSC is poorly studied compared to other exposed subduction mélanges, and our study constitutes some of the first structural work in this area since the 1970s.
Nicole Aikin Timing is everything in the right context - Monazite Petrochronology of the Grand Canyon Vishnu Schist reveals the lifecycle of an Orogen
TBD
Alysa Fintel Architecture of an Active Tsunamigenic Splay Fault: Outcrop to micro-scale structure of the Patton Bay Fault, Montague Island, Alaska
In the 1964 Mw9.2 megathrust earthquake in south-central Alaska, the Patton Bay splay fault hosted coseismic rupture both offshore and on Montague Island with up to 10 m of throw along the surface. The offshore expression of this fault has been proposed to be a source of the subsequent local tsunami. Tsunami-genesis can be influenced by surface rupture of shallow, megathrust-related splay faults and how they transfer seismic slip from a megathrust rupture path to the surface. The 1964 rupture came to the surface along the Strike Creek strand of the PBF fault, but the locus of major long-term displacement is the nearby Deception Creek strand, which is well-exposed on an intertidal wave-cut platform. This unique on-land exposure of an active megathrust splay fault presents the opportunity to investigate the geometry, fault zone architecture, mechanical properties and alteration from host rock to fault core. Macro- and micro-structural observations are being used to determine the fault zone and fault rock properties that reflect earthquake processes. Microstructural analysis will include identifying potential cataclasite formation, fluidized fault rocks, foliated fault gouge, shear sense, and mineralogical or geochemical signatures of frictional heating, each potentially a signature of past seismicity. We identified and documented field-scale structural zones including hanging wall and footwall damage zones and a fault inner and outer core. The fault zone is ~150-m wide, with damage zones made up of highly fractured bedrock, disrupted bedding, cataclasite-rich patches, and a nearly continuous gouge-rich fault core ~8-m wide. The damage zone of the hanging wall has varying degrees of disrupted bedding, local cataclasite formation, and fracturing, whereas the damage zone of the footwall is primarily intensely fractured bedrock with little cataclasite formation. This exposed fault exhibits structural variations consistent with a mature brittle fault with a single principal slip zone that is surrounded by a fractured damage zone. These structural characteristics have been described in other seismogenic splay fault studies and support the conclusion that Deception Creek fault is the primary strand of the Patton Bay Fault on Montague Island and has historically ruptured in great earthquakes.
Sophie Johnson Rheology of a foundering arc root from the Northern Andes from naturally deformed xenoliths
Xenoliths enable direct petrologic and microstructural study of inaccessible portions of the lithospheric column in modern subduction zones which can often be poorly preserved or absent in the exhumed paleosubduction rock record. The Northern Volcanic Zone (NVZ) of the Andean arc currently hosts a thickened continental crustal root that records a geophysically observed lithospheric drip. Lithosperhic drips, or the foundering of gravitationally unstable material into the mantle, are hypothesized to play a significant role in generating a geochemically evolved bulk continental crust and recycling crustal material into the mantle. Yet the mechanisms that facilitate this lithospheric removal are poorly understood, including the viscosities of the crust and mantle accommodating this delamination. We present petrographic and EBSD analysis of 8 crustal xenoliths from the NVZ to constrain the rheology, deformation mechanisms, and ultimately the viscosity of overthickened delaminating lower arc crust during active dripping. The granulite-amphibolite facies mafic xenoliths contain amphibole, clinopyroxene, garnet, plagioclase, quartz, and Fe-Ti oxides. Quartz and clinopyroxene show evidence of dislocation accommodated deformation through grain boundary migration and subgrain rotation respectively, while plagioclase microstructures reveal evidence of hypersolidus deformation. Crystallographic preferred orientations (CPOs) of clinopyroxene and amphibole suggest activation of the [001](100) slip system producing a strong [001] CPO parallel to the apparent foliation. Amphibole is abundant in many of the xenoliths and is likely an important control on the bulk rock strength but remains rheologically poorly constrained. The 8 samples record microstructures that reveal a range of deformation mechanisms and deformation accommodating phases. The xenoliths represent a geologically recent record of the NVZ of the Andean arc thus providing insight into poorly understood mechanisms occurring at an active and geologically significant tectonic margin.
Diversity, Equity, and Inclusion (1:00pm - 2:00pm):
Alysa Fintel and Nicole Aikin Disability Resources and Accessibility within the Department
TBD
Madeleine Lucas Integrating culture and science at the Quileute Tribal School through community-driven earthquake monitoring
Through their Move to Higher Ground project (mthg.org), the Quileute Tribe, located in La Push, Washington, has led the way in adapting to coastal hazards in Cascadia. The time and effort required to develop trust with tribal nations is a major barrier for academic entities aiming to build partnerships with tribes. Over the last decade, the University of Washington’s NASA-funded Riverways Program has worked with tribal communities across Washington state to address inequities in public education. Through the development and teaching of hands-on STEM curriculum that centers indigenous culture and place-based learning, the Riverways program actively contributes to the diversification and training of the next generation of Earth scientists. Over the past two years, I have led a team of UW students to develop and teach week-long Earth Science curricula focused on geology (2022-23) and seismology (2023-24) to high school students at the Quileute Tribal School (QTS) over UW’s spring break as part of the Riverways STEM Alternative Spring Break (STEM ASB) program. This year, with support from the NSF-funded Cascadia CoPes Hub, I expanded this program into a year-long engagement with QTS through the Riverways Culture and Science Exchange (CASE) Program. The CASE program includes STEM ASB along with multiple mentoring visits to QTS over the year and a visit by QTS high schoolers to UW Campus. The CASE program cultivates STEM identities among indigenous high school students at QTS, empowering them to pursue STEM career pathways. This year’s CASE seismology program includes a paid student internship where three QTS high schoolers are working as a team to install a RaspberryShake seismometer at QTS, design and build a community seismic display, monitor earthquakes, and translate seismological terms into Quileute. Through these efforts, I have built strong relationships with QTS students and teachers, Quileute Tribe members, and the Riverways Program. My connection with these programs will provide a basis of trust that will strengthen and promote future partnerships and collaborations between the University of Washington and the Quileute Tribe.
Jess Ghent Santiago Atitlán, Guatemala: Inequities and ways of living following the 2005 Panabaj landslide
TBD
Tamara Aranguiz Code to Communicate: Empowering Bilingual Connections in Earth Science
Code to Communicate is a virtual, bilingual program directed at early-career researchers that offers training in Python programming and SciComm. It was created in 2021 by the co-founders of two GeoLatinas. Our program boasts a team of early-career coaches/scientists from Argentina, Venezuela, Mexico, Puerto Rico, Colombia, and Chile recruited from the extensive GeoLatinas network. CoCo recruits a diverse cohort of Latine participants seeking Python and SciComm bilingual training. By targeting students who have challenges due to language barriers, we reach the population who will most benefit from our bilingual program. CoCo promotes inclusivity by offering free online course materials and engagement in English and Spanish. Our 10-week virtual program offered comprehensive training, with weekly classes focusing on Python libraries for data management, processing, and data visualization for geosciences. SciComm lectures increase awareness of communication strategies and the importance of producing information accessible to diverse audiences. CoCo received 112 applications in 2022 and 2023 and accepted 34 participants (21 in 2022 and 13 in 2023) from across the United States, Latin America, and Europe, all of whom self-identified as Latine, Hispanic, Latinx, or similar. Our surveys indicated that participants felt overwhelmingly more confident in their ability to use Python and were excited about their growing abilities in general and with specific tools. Participants also expressed appreciation for the bilingual nature of CoCo and particularly for the ability to learn in two languages with the freedom to decide which language works best. This 2024, CoCo program is transforming into CoCo Community, looking to increase accessibility, offering a virtual space to get support in coding and Scicomm questions that can connect Latine researchers from any stage of their career.
Outreach and Education (2:15pm - 3:00pm):
Autum Downey, Lucas Fifer, and Pete Wynn Raising eSTEAM: Providing Tutoring & Hands-on Science Activities to Incarcerated Youth
Juvenile detention centers are required to provide education, however resources are often limited, and instruction can be inconsistent both in terms of timing and content. In recent years, there has been increased attention in addressing this inequality, and programs have taken shape such as the Princeton Teaching Initiative, the Initiative to bring Science Programs to the Incarcerated (INSPIRE) and Astrobiology for the Incarcerated. Inspired by these outreach programs, a group of UW astrobiology students (including several from ESS) established Raising eSTEAM (education in Science, Technology, Engineering, Astrobiology/Art, and Mathematics). Over the past two years, our volunteers have been visiting a juvenile detention center in Snoqualmie, WA on a weekly basis to provide tutoring and mentoring for high school equivalency courses across a wide range of subjects. This past year we expanded our efforts, developing several hands-on science activities, with a focus on astrobiology. Activities included solar viewing, a Mars Viking experiment analog, an impact cratering demo, and a mobile planetarium show. These activities are intended to be separate from the children’s enforced routine by providing fun and interactive educational experiences. We have received funding from Autodesk and through a NASA Space Grant Graduate Fellowship and our work was featured in the inaugural Between Two Spheres ESS newsletter and Popular Science. This talk will focus on our culminated efforts and experiences in designing and implementing science outreach for incarcerated youth.
Jessica Ghent Considering evacuation realities in Fuego Volcano’s active hazard zones
TBD
Anna Ledeczi Rockin' Out: Earth Science Outreach K-12 Outreach in Seattle and Beyond
Rockin’ Out is the ESS department’s graduate student-run K-12 outreach program that has been running for over 15 years. With the help of volunteers, we visit schools, offer field trips, lead hands-on activities, and host lab tours to teach students about geoscience. Since 2021, we have held 46 events which reached over 6500 students and families in total. Our long-term plans are developing a more robust, PNW-centric geohazards curriculum by working closely with Cailey Condit. She plans to teach a quarter-length curriculum development seminar in the next year that will be open to graduate students and advanced undergraduates interested in building teaching skills while developing Rockin’ Out curriculum to help us reach a wider audience. We envision Rockin’ Out growing in the coming years with the support of more student, faculty, and staff volunteers in ESS who are excited about geoscience outreach. We hope to encourage more lab groups to develop exciting lab tours, and for excited field geoscientists to help design accessible Seattle-based field trips. Keeping an eye out for volunteer opportunities from the Rockin’ Out email list is the best way to get involved!
Geodesy (10:00am - 11:00am):
Jonathan Gates The 2021 Resurgence in Deformation at the Three Sisters Volcanic Field, Oregon Cascades
A specific example of deformation and uplift accompanied by minimal seismicity is observed in the Three Sisters volcanic field in central Oregon, which consists of 460 vents of the Quaternary age. The area of interest, situated 6 km west of the South Sister volcano, has been experiencing uplift since the late 1990s, with previous studies suggesting that this uplift may be attributed to the injection of magma emplaced at a depth of 5-6 km. This uplift has a consistent yet slowing rate of uplift, reaching a maximum rate of 3-5 cm/yr between 1998 and 2001. On January 31, 2022, the U.S. Geological Survey reported a change in the uplift rate, with satellite radar images indicating an uplift of approximately 3 cm between the summer of 2020 and August 2021 in the same region where uplift had been previously observed. We employed interferometric synthetic aperture radar and continuous GPS data to model the magmatic intrusion of the most recent inflation episode. The project seeks to assess the significance of aseismic volcanic inflation and unrest, while contributing to the understanding of mid-crust magma storage beneath the Three Sisters
Jensen DeGrande Putting the Pieces Together: A Kinematic Coseismic Model of the Mw 7.2 Alaska Earthquake
A Mw 7.2 earthquake occurred in July 2023 offshore the Alaska Peninsula, rupturing a western portion of the Shumagin Gap. Three years prior in July 2020, a Mw 7.8 event ruptured the eastern portion of the gap, previously known for being devoid of large earthquakes over the last century and characterized by low geodetic coupling. Later in 2020, a Mw 7.6 event strike-slip earthquake potentially ruptured the central portion of the gap as evidenced by tsunami data, updip of the July, 2020 Mw 7.8 earthquake. Deeper postseismic deformation was evident after the July, 2020 earthquake. Here we investigate the kinematic rupture of the July, 2023 Mw 7.2 event using a joint inversion of high-rate GNSS, strong motion data, and static offsets recorded during the event. We utilize MudPy, an open-source, multi-data source modeling and inversion toolkit available on GitHub, with an 800-patch mesh of the subduction slab to assess the slip distribution. We analyze the full sequence of these events, including co-seismic and post-seismic slip, over the past three years to understand the release of accumulated strain at certain depths in this portion of the Alaska-Aleutian Subduction Zone. With the recent > Mw 7 events in the Shumagin Gap, we investigate how the 2023 Mw 7.2 event fits in relation to the other events within the past three years to gain an understanding of the coupling of the region and the partial filling of the Shumagin seismic gap to enhance hazard mitigation and assessment in the region.
Anna Pearson The Distribution of Interseismic Locking on the Cascadia Subduction Zone Using Bayesian Methods
We present a Bayesian inversion for the locking distribution on the Cascadia Subduction Zone. Cascadia has potential for significant seismic and tsunamigenic hazard, with geodetic data indicating that interseismic elastic strain is accumulating along the plate boundary. However, the extent of the locked zone is difficult to evaluate, with many non-unique solutions. To evaluate the full set of model parameters that fit the available data, we incorporate a probabilistic framework. Our dataset contains averaged horizontal and vertical GNSS velocity solutions from multiple processing centers, as well as multi-decadal leveling data. We use the CATMIP algorithm as implemented in the AlTar program to invert for the family of models that fit both the data and a prior assumption of the locking pattern. We test a series of different priors, including different updip and downdip limits of locking as well as heterogeneous locking patterns based on fault properties. We explore methods of using the data covariance matrix to account for data biases, such as glacial isostatic adjustment and viscoelastic effects. Results include an updated locking model, showing the statistical distribution of model parameters that fit the data. We also show a range of results that explore the sensitivity to different priors and estimates of data covariance. Results indicate consistency with previous work, showing strong locking at the trench, decreasing with depth. However, the spread of models that fit the data and its associated uncertainty varies significantly in terms of the degree of locking at the trench, depth limit, and uniformity of locking pattern. This has implications for predicted seismic and tsunamigenic hazard assessments in the region, which should consider a probabilistic approach to incorporating locking models as constraints.
Geochemistry (1:15pm - 2:30pm):
Annika Jorgenson Lake Sediment Isotopic Record of Western North American Climate Change From 16 to 6 Million Years Ago, Arizona, USA
The mid-Miocene climatic optimum (17-14 million years ago) and subsequent cooling is an important global climate event that affected the North American continental interior’s temperatures, ecosystems, and hydrology. These effects can be studied using isotopic records of surface temperature and hydrologic conditions from 16 to 6 million-year-old lake minerals (carbonate) on the southern Colorado Plateau–the Bidahochi Formation. Lake carbonate bulk isotopic values measure the abundance of heavy to light carbon and oxygen isotopes (d13C and d18O), and clumped analysis (∆47, ∆48) examines the bonding of heavy isotopes that reflect carbonate growth temperatures. However, the temperature estimates derived from clumped isotope data (T∆47 and T∆48) assume mineral growth under isotopic equilibrium, which may not be true for all lake samples. Disagreement of apparent temperatures T∆47 and T∆48 and covariance with d13C and d18O values can assess non-equilibrium. In cases where carbonates precipitated out of equilibrium, applying both ∆47 and ∆48 data (dual-clumped isotope thermometry), and using models to understand the mechanism for disequilibrium (e.g., kinetic isotope effects) allows for the reconstruction of true growth temperature. Here we analyze different types of lake carbonates using sample textures and d13C, d18O, ∆47, and ∆48 covariance to determine if they grew in or out of kinetic equilibrium and reconstruct depositional temperatures. Preliminary results support the hypothesis that lake carbonates that formed at the surface and settled into deeper water (marls) precipitated in equilibrium and recorded accurate temperatures, while carbonates formed at lake margins affected by groundwater (tufas) grew quickly and may have experienced kinetic effects that require dual-clumped analysis to reconstruct their growth temperatures. The temperature record that we build using ∆47 and ∆48 data will give a data set of surface temperatures in the North American continental interior throughout the mid-Miocene climatic optimum further constraining paleoclimate records.
Xuefei Fan A global perspective on heavy Mg isotope in island arc basalts
A growing body of literature shows that arc basalts are enriched in isotopically heavy Mg compared to normal mantle values exhibited by MORBs and OIBs. The enrichment of 26Mg in arc basalts has been attributed to slab-derived fluids, while the source of the fluid in the slab is unclear. Other hypothesis suggests equilibrium olivine fractionation may drive basaltic melt to high δ26Mg. To resolve the contribution of these two processes to the heavy Mg isotope composition in arc basalts, we report magnesium isotope composition of island arc basalts from Eastern Aleutian, South Sandwich Islands (SSIs), and Costa Rica. These arc basalts mostly have δ26Mg heavier than MORB mantle values and show large inter-arc variation: -0.157 to -0.034‰ for Aleutians, -0.206 to -0.068 ‰ for SSIs and -0.229 to -0.074‰ for Costa Rica. We also compile literature data for Quaternary island arc basalts from Lesser Antilles and Kamchatka. These subduction zone localities exhibit a large range of slab thermal states, subduction sediment input, as well as δ26Mg in arc basalts. We model the effect of olivine fractionation using a Rayleigh distillation model using equilibrium isotope fractionation factor. The olivine corrected δ26Mg in primitive melts still show large inter arc variation, suggesting additional factors at play. Correlation between the normalized δ26Mg with arc subduction parameters such as the slab thermal parameter, slab dip angle and overriding crustal thickness suggest that the heavy Mg enriched fluid may arise from the serpentinitzed slab interiors.
Pete Wynn Magnesium isotopes suggest a non-carbonate origin for magmatic CO2 in Earth’s biggest-ever large igneous province event
Large igneous province (LIP) volcanism links Earth’s shallow and deep carbon cycles and has coincided with several major Phanerozoic mass extinctions. The Central Atlantic magmatic province (CAMP), emplaced ca. 201.6 – 200.9 Ma, is the largest known LIP event in terms of total magma volume and emplacement surface area. CAMP magmas were also enriched in CO2 and S, contributing in part to the drastic environmental changes that occurred globally soon after emplacement began. The origin of CAMP carbon is still poorly constrained. Modeling based on melt inclusions suggests that at least some of the magmatic CO2 may have been assimilated from metasedimentary rocks in the middle crust overlying the CAMP mantle source. An alternative explanation for the CO2 is recycling of sediments to the mantle during ancient subduction events. Magnesium isotopes have emerged as a tool for tracing carbonate subduction to the mantle. The Mg isotopic composition of carbonates is significantly lighter than the mantle, and addition of carbonates to the mantle during subduction can impart a signal that is later measurable in erupted lavas. This study reports the Mg isotopic composition of 50 CAMP basalts selected from geographic and geochemical endmembers to assess the origin of CAMP magmatic CO2. CAMP Mg isotope values range from δ26Mg (‰) = –0.25 to +0.05, overlapping the average mantle value (δ26Mg = –0.25 ± 0.04‰). No evidence of carbonate-derived magnesium was observed in any of the CAMP rocks based on their measured Mg isotopic composition. CAMP basalt Mg isotope values do suggest involvement of siliceous sediments in their formation, but further modeling is needed to explore where and when these sediments were added to CAMP magmas. Previous trace element and radio-isotope studies provide an architecture for using Mg isotope data to build out these models.
Autum Downey Evidence for conformational changes to the cell surface of a deep sea methanogen induced by the presence of divalent cations
Archaeal cell envelopes contain a distinct semi-crystaline proteinaceous surface layer (S-layer), which is a structure fundamentally different from most bacterial cell surfaces. Surface interactions between archaeal cells and the surrounding environment has been relatively understudied compared to bacterial cells. This includes investigating S-layer reactions under conditions similar to in-situ environments. Here we compare the chemical characteristics of the cell surface of a deep sea methanogen Methanocaldoccocus sp. FS406-22 via attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy under two distinct conditions: (1) a simple 0.56 molar NaCl solution and (2) a 0.56 molar ‘simulated’ seawater solution. ATR-FTIR spectra reveal evidence that magnesium and calcium induced significant changes to the portion of the spectra corresponding to ether (C-O-C) bonds. The observed variation in collected spectra is likely a result of magnesium/calcium adsorption to the cell surface. The adsorption of divalent cations results in significant conformational changes to the cell surface, likely adding increased structural stability to the cell. This work represents the first direct evidence of environmentally induced conformational changes to the cell surface of a hyperthermophilic methanogen. Within a realistic in-situ environment, the conformational impacts to the cell surface induced by calcium and magnesium could alter the overall surface reactivity and possibly is an important mechanism contributing to efficient micro-nutrient uptake.
Andrea Nodal Modeling Co Adsorption onto a novel methanogen cell surface
Methanogenisis is a metabolic strategy in which anaerobic archaea produce methane as a byproduct of growth. These archaea, called methanogens, must adsorb several key metals to successfully perform methanogenesis. One such metal is cobalt. While the methanogen may have cobalt in its environment, it must still outcompete other ligands in solution that can potentially form complexes with that cobalt, rendering it unavailable. FS406-22 is a very recently discovered hyperthermophilic methanogen, of particular interest because of its capacity to withstand the harsh environments of hydrothermal vents. Very little is known about the growth strategies and limitations of this organism. This project uses surface complexation modeling to quantify the ability of FS406-22 to adsorb cobalt in varying environmental conditions. Understanding cobalt adsorption by FS406-22 in the presence of other ligands will give us insight to how it is able to survive in the extreme environments it is found, and how changes in those environments will affect its metabolic efficiency.
Glaciology and Paleoclimate (2:45pm - 4:00pm):
John-Morgan Manos Distributed Temperature Sensing (DTS) reveals climate signals and ice mechanics
TBD
Marguerite Shaya Phase-sensitive radar measurements of vertical strain rates in the Allan Hills, Antarctica
At the Allan Hills blue ice area in Antarctica, surface ablation and steeply rising bedrock topography uplift ancient (1 Ma to almost 6 Ma) layers of ice towards the surface. Because this ice provides snapshots of greenhouse gas concentrations in past climates such as the early Pleistocene and the Pliocene, the Center for Oldest Ice Exploration (COLDEX) is prioritizing drilling shallow (~200 m) cores in the Allan Hills ablation zone and is committed to drilling an intermediate depth ice core (~1000 m) in the accumulation zone if logistically feasible. Understanding the ice flow dynamics leading to the preservation of old ice at the Allan Hills, as well as the stratigraphic sequence of the ice, is necessary to (1) provide context for existing ice core samples that may have traveled long distances and undergone complicated deformation or folding and (2) support site selection for drilling for ancient ice in other blue ice areas. We present 26 repeat phase sensitive radar measurements collected during the 2022-23 and 2023-24 field seasons which provide new constraints on englacial ice flow. Repeat phase-sensitive radar measurements can track the vertical displacement of internal reflecting horizons with millimeter precision, yielding measurements of vertical velocities and strain rates across the full depth profile in these locations. The sites span the accumulation zone and ablation zone and align with previously measured radar profiles of the bed and internal layering; the dataset includes 12 measurements along the principal flowline (Track 4) and 6 measurements connecting that flowline to the shallow drilling camp (Track 5) all at approximately one-kilometer spacing. We observe negative (downward) vertical velocities in the accumulation zone and positive (upward) vertical velocities in the ablation zone, consistent with GPS measurements of surface velocities. Combined with repeat surveys of a GPS strain grid deployed in the 2023-24 field season, these data will provide powerful constraints on the ice flow history at the Allan Hills.
Liam Kirkpatrick Ice Cores, like Onions, have Layers: A Multi-Proxy Study of Layering in Allan Hills Ice Cores
Recent drilling at the Allan Hills blue ice region of Antarctica has produced ice cores extending well past the existing 800 kyr ice core record, with some samples as old as 6000 kyr. These ice cores provide novel insight into Pleistocene climate, including greenhouse gas concentrations, mean ocean temperature, and local temperature. However, interpretation of these cores is limited by poor understanding of ice stratigraphy at the site. Discontinuities, folding, and mixing of ice all may significantly impact the paleoclimate record developed from these cores. Here we present a novel multi-proxy study of layering in an Allan Hills ice core, which provides new insight into layer structure and composition. We focus on a single piece of ~1400 kyr ice located 5 m above the bed. Multi-track Electrical Conductivity Measurements (ECM) are used to identify and characterize strongly dipping layering in this sample. Duplicate water isotope measurements show the ECM layering is aligned with other proxies which do not directly influence conductivity. Ion chromatography and Coulter Counter measurements are used to identify the major ion and dust content of the observed layers. We discuss possible origins of the stratigraphy and implications for the interpretation of the Allan Hills ice cores. This study emphasizes the importance of considering sub-meter scale stratigraphy to maximize the utility and accuracy of blue ice region ice core records.
Marc Sailer Modeling Atmospheric Gas Diffusion for Deep Ice Core Site Selection between the South Pole and Dome A
The Mid-Pleistocene Transition (MPT) was a major climatic shift in Earth’s history occurring between 1.2 and 0.7 million years ago. During the MPT, Earth’s glacial cycles shifted from a high frequency (~40 kyr), low amplitude cadence to a low frequency (~100 kyr), high amplitude cadence which has dominated since the MPT. While we are able to observe the MPT in benthic 𝛿18O records, our current ice core record only extends back 800 kyr and does not include a preservation of the entire MPT. COLDEX, a multi-institution collaboration, is seeking to find a region in Antarctica where a continuous deep ice core may preserve the MPT in order to better understand the underlying mechanisms that caused it. Ice at this depth, however, is subject to much different conditions than the ice cores that comprise our current record. My study aims to analyze how atmospheric gases, namely CO2 and the 𝛿O2/N2 ratio (used to identify precessional cycles for dating ice cores), diffuse in Antarctic ice of 1 to 1.5 million years old. I focused on the COLDEX survey region between the South Pole and Dome A. I employed two models: 1) a one-dimensional steady state model which calculates the temperature and age of the ice with respect to depth, and 2) a gas-diffusion model which uses the temperature- and age-depth relations to calculate the amplitude of the gas signals in the ice through time. The input parameters for these models are measured using aerial radar, provided by COLDEX, or interpolated accordingly. So far, I have found that CO2 is relatively well preserved in the region, while the 𝛿O2/N2 ratio is much less well preserved. This suggests that finding an ideal region for a deep ice core drill site, on the basis of gas diffusion, may be difficult.
Vigash Ravi Deciphering Ancient Climate Amidst the Lithium Boom: Exploring Salar de Atacama, Chile
The Salar de Atacama Basin (SdA) in northern Chile is one of the worlds largest lithium brine deposits and contributes nearly 30% of global lithium production. Investigating the past climate of the SdA gives us a better understanding of how minerals were introduced and concentrated in the basin via reconstruction of ancient depositional environments and facies in addition to stable isotope paleoclimate proxies. We employ sedimentological core descriptions and make stratigraphic correlations along the southeastern part of the SdA using new ages from intercalated volcanic ashes. Initial results indicate that the cores preserve a 0.94 to 2.45 Myr record. A diverse range of depositional facies were identified corresponding to the following depositional environments: lagoons, salt pan, and ephemeral streams. The primary core studied here (PN08) is unique in its location at the margin of the transition zone of the salar, an area where cores have not yet been described. Planned future work includes 13C and 18O stable isotope analyses of carbonates. These results will inform the paleoclimate history of the region, including delineating wetter and drier phases.
Seismology (9:00am - 10:15am):
Dominik Graeff Sensing the Calving Front of a Tidewater Glacier with an Optical Fiber
Calving fronts are the nexus where atmospheric and oceanic forcings on the cryosphere condense. Dynamic processes acting on them not only impact future tidewater glacier evolution but control the stability of the Greenland Ice Sheet. Rapid changes in these processes caused by global warming potentially result in the partial disintegration of the ice sheet with imminent environmental and socio-economic consequences on regional and global scales. In summer 2023, we installed a subsea fiber-optic cable across a Greenlandic fjord on the seafloor and parallel to the calving front of a tidewater outlet glacier. Over three weeks, we used the optical fiber itself as a 7km long linear array of temperature and vibration sensors. By utilizing Distributed Temperature and Acoustic Sensing (DTS, DAS), we measured temperature every 25cm on 30’000 sensing points and strain-rate every 5m on 1’500 sensing points along the cable. DTS recorded the water temperature spatially resolved across the fjord, how it evolves through the melting season, and how the fjord’s water layering is perturbed by iceberg calving events. With the DAS recordings, we locate these calving events and the ice fracturing by waves traveling directly through the water and along the water-sediment interface. We further determine enhanced seafloor currents during the passage of internal waves, that are excited by calving events and can be linked to vibrational modes of the fiber-optic from vortex shedding. Finally, DAS senses how tsunamis caused by iceberg-calving travel across the fjord towards the shore.
Akash Kharita Towards Automated Detection of Surface Events in the Pacific Northwest
Systematic monitoring of mass movements, such as landslides, avalanches, rockfalls, and debris flows, is vital for mitigating risks in places where such events threaten to impact people or infrastructure. The Pacific Northwest Seismic Network (PNSN) detects a subset of surface events as a byproduct of the routine detection and location workflow for tectonic and volcanic earthquakes. In this study, we explore a vast range of feature space and model architecture designs for event classification. We found that the random forest algorithm along with a specific set of features is the best model for its generalization over the PNW data sets. We trained our model on a curated set of waveforms from Ni et al. (2023) for earthquakes and other seismic sources recorded by the PNSN over the past 20 years and developed a workflow that can be deployed on continuous data. We then used our model to automatically detect and characterize events at Mount Rainier, identifying surface events in a month of continuous data from three seismic stations. The model successfully identified all surface events manually picked by PNSN analysts for the study period with a high classification probability exceeding 0.9. Additionally, it detected approximately ten times more surface events with a high probability of 0.8, with a subsequent manual review revealing their resemblance to waveforms of verified surface events or volcanic events. In one attempt to validate our new detections, we computed maximum cross-correlation coefficients of detected event waveforms with ground-truthed surface events in the Earthscope Exotic Seismic Event Catalog for the Mount Rainier region and found that many of the detected surface event waveforms exhibited high correlation coefficient values exceeding 0.9. We also report their approximate location using phase picking of the onset of the emergent waveforms and use a grid-search method for determining locations using a uniform velocity model. Ongoing efforts to generate better training catalogs and to verify new detections involve incorporating additional stations, DAS, eyewitness accounts, and infrasound data.
Verónica Gaete-Elgueta Use of Distributed Acoustic Sensing as a tool for monitoring geohazards at Mt. Rainier
Distributed Acoustic Sensing (DAS) is a new and expanding technology used to monitor seismic events with optical fiber cables as a distributed array of one-dimensional strain sensors. In this work, we investigate the potential of using a dark fiber, an optical fiber deployed for telecommunications purposes, to monitor seismic activity in and around Mt. Rainier, a glaciated, active stratovolcano in the Cascades Volcanic Arc, USA, and is monitored by the Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN). Mt. Rainier hosts a broad spectrum of geohazards such as earthquakes, debris flows, landslides, and various cryospheric hazards such as icequakes or avalanches that present a risk to nearby urban areas. In this study, we use DAS recording on a 48 km long cable, with more than ∼ 4,000 channels, buried under the road between Ashford, Washington and Henry M. Jackson Memorial Visitor Center on the flank of Mount Rainier. We apply template matching to the DAS data, using events in the PNSN earthquake and surface-event catalog to search for events not detected by the permanent monitoring network. We use USGS catalog to select a big magnitude event and then search for it on DAS data, and then process that event as a template to do the continuous search on the data. In addition to the activity at the volcano, our dark fiber experiment recorded a tectonic earthquake swarm in August 2023, located Western Rainier Seismic Zone. This more complete earthquake catalog will be used to perform double-difference relocation and tomography to improve our understanding of fault structures within the Western Rainier Seismic Zone. We also perform preliminary analysis to detect and identify other event types, including surface events, volcano tectonic earthquakes, and other volcanic events. Our study presents the groundwork for the use of DAS to monitor volcanoes in near real time.
Manuela Köpfli Shallow Volcanic Subsurface Monitoring Through Distributed Acoustic Sensing (DAS): Insights from Mount Rainier
In our ongoing endeavor to enhance volcanic monitoring, we have incorporated Distributed Acoustic Sensing (DAS) technology into our data collection efforts at Mount Rainier since the summer of 2023. Despite the inherent challenge of higher noise levels compared to traditional seismometers, the spatial density afforded by DAS presents a unique opportunity. Our network of "virtual" sensors enables us to employ advanced seismic wavefield techniques such as cross-correlation and wavefield coherence analysis. Through these methods, we aim to monitor the shallow subsurface dynamics between the volcano and the Nisqually River. Our research extends beyond seismic activity alone. We are leveraging DAS data to quantify river discharge, utilizing comparisons with meteorological data to deepen our understanding of hydrological processes. Furthermore, our investigation delves into the water saturation levels of the subsurface and freezing cycles, seeking correlations with environmental factors such as temperature, snow depth, and precipitation patterns. By integrating these diverse datasets, we aim to elucidate complex relationships between the occurrence of mass movement events and the surrounding environmental conditions. Ultimately, this holistic approach promises insights into the dynamics of volcanic systems and their interactions with the broader landscape. We hope that a better understanding of the relation between mass movement events helps to improve hazard assessment and risk mitigation strategies in volcanic regions, contributing to the advancement of both scientific knowledge and public safety initiatives.
Elisabeth Olson Seafloor Channels within Cascadia
Subduction occurs when denser plates sink below less dense plates, sometimes this process can accrete surface material. Previous studies have hypothesized that there are distinct geomorphic patterns present in bathymetry data related to accretionary wedge deformation. At the Cascadia Subduction Zone, accretionary wedge splay faults show evidence for interaction with seafloor channels. Slip on splay faults during future Cascadia megathrust earthquakes has the potential to displace large amounts of seawater, posing a serious tsunami threat to coastal communities in Cascadia. Therefore, by mapping geomorphic patterns and investigating seafloor channels in the Cascadia accretionary wedge, we will be able to further our existing knowledge of where splay faults are active and have the potential to slip in future earthquakes. Here I analyze a newly acquired 30-meter USGS digital elevation model (DEM) of the offshore Cascadia accretionary wedge. I aim to isolate potentially active splay fault zones through geomorphic analysis of seafloor channels using ArcGIS Pro and MATLAB Topo Toolbox. It is predicted that where seafloor channels intersect active splay faults, there will be a disturbance in the channel profile. In this study, my goal is to demonstrate the interaction between splay fault activity and channel morphology to better understand hazards at the Cascadia Subduction Zone.
Planetary Science (10:30am - 11:30am):
Andrew Shumway Novel Micro-XRF Measurements of Regolith in Jezero Crater, Mars
The surface of Mars is covered with loose, unconsolidated material called regolith (AKA soil). Regolith has a near-uniform composition across the surface of Mars, records crucial information about the planet’s geologic history, and can offer clues about whether past environments might have been habitable. On modern Mars, regolith may also help form and stabilize liquid water, which can enable geochemical weathering, mobilize soluble species through the soil, and potentially create habitable environments. Here, we report results from the first-ever micro-scale X-ray fluorescence (XRF) investigations of Martian regolith, which were conducted by the Planetary Instrument for X-ray Lithochemistry (PIXL) onboard the Mars 2020 Perseverance rover in Jezero Crater. PIXL’s narrow beam (~120 μm) and ability to make contiguous measurements in a raster allowed us to interrogate regolith composition and texture at a higher resolution than ever before. With PIXL, we measured the abundance of elements heavier than sodium (i.e., Z > 10) and probed the crystallinity of regolith on the scale of individual grains. We then used an unsupervised machine learning technique (K-means clustering) to group grains based on their composition and whether or not we detected diffraction. The results demonstrate that regolith contains a diverse minerology made up of a globally-homogenous, well-mixed soil unit plus larger fragments contributed from local lithologies. The regolith investigated also records a variety of alteration styles, which provides insights into potential past environments of Jezero Crater and Mars broadly. Finally, these findings further motivate the upcoming Mars Sample Return campaign, which would retrieve regolith samples collected from this site and return them to Earth for future study of the geologic history and potential habitability of Mars.
An Li Insights from Ground-Penetrating Radar of Icelandic Eskers for Sinuous Ridges on Mars
While most ice deposits on Mars are considered to be cold-based, recent work has presented evidence for more wet-based glaciation. One increasingly common example is eskers, sinuous ridges deposited by subglacial channels of meltwater, which are indicative of wet-based glaciation. While other formation mechanisms have been proposed for these sinuous ridges, the leading hypothesis is glacial since these sinuous ridges do not follow topographic slopes and have been found to be statistically similar to terrestrial eskers in terms of their morphology. Previous studies of terrestrial eskers have not examined eskers on volcanic bedrock, a substrate similar to what we might expect on Mars. In spring of 2023, we conducted geomorphic, sedimentological, compositional, and geophysical field analyses at an analog esker site sourced by sediment coming from mafic bedrock. This presentation focuses on the geophysical findings from the field site at Breiðamerkurjökull, an outlet glacier in southeast Iceland. We collected 76 ground-penetrating radar (GPR) survey lines using 100, 200 and 500 MHz antennas at three different eskers ranging from 2.5 to 10 meters in maximum height and at the terminus of the glacier. Preliminary results show the locations of an ice cave and ice bridge in the glacier. In addition, for the most recently exposed esker, we identify buried ice in the esker using the changes in polarity due to shifts in radar velocity. Future work will focus on finishing processing of the GPR lines and comparing the radar facies with previous work to evaluate the morphogenesis of these eskers.
Anna Grace Ulses Ruling out False-positive Biosignatures on Ocean-worlds
Molecular oxygen is a widely studied biosignature because of its association with photosynthetic life, and the apparent low likelihood of an O2-rich atmosphere developing on a lifeless planet. However, abiotic O2 may still be generated on habitable zone planets through several proposed evolutionary scenarios resulting in ‘false-positive’ biosignatures. One such scenario leads to an ocean-dominated planet, called a waterworld. These worlds are the evolutionary result of planets that have initial H2O inventories exceeding ~50 Earth oceans. The pressure from such large surface water inventories increases the solidus of the silicate mantle and rapidly terminates crustal production. The cessation of crustal cycling removes geological oxygen sinks, and oxygen slowly builds up in the atmosphere via diffusion-limited escape of hydrogen. However, this false positive would be excluded by the detection of exposed land features, since there is a predictable maximum limit to topography based on the crushing strength of silicate rock. Based on this principle, we investigate the telescope capabilities needed to detect land using simulated reflected light retrievals of Earth-like and waterworld planets. Retrievals will be presented for a variety of land surface types and land fractions to determine the signal-to-noise, telescope aperture, wavelength range, and integration time required to exclude waterworld false positives with confidence. This builds on previous work that has demonstrated the retrieval of the red edge given sufficient signal-to-noise and spectral resolution, and directly informs the Habitable Worlds Observatory (HWO) capabilities required to identify waterworld false positives.
Haskelle White Thermodynamic Modeling of Alterations During Climate Transition Reveals Evidence of Past Temperate Conditions on Venus
The possibility of habitable conditions with abundant liquid water and cooler temperatures in the history of Venus remains a long-standing question in the exploration of Earth’s twin sister. Understanding Venus’ transition to its present inhospitable state is critical to determining terrestrial planets’ evolution pathways and their impact on habitability. However, how this transition occurred is not well understood, as Venus’ thick atmosphere and recent volcanic resurfacing obscures surface observations. Here, we present a thermodynamic model of Venus’ geochemical evolution during this transition period to find mineral and gas markers indicative of earlier atmospheric conditions. We simulate the interactions between various crustal models, the paleo-ocean, and the atmosphere as the planet’s surface temperatures increase during a runaway greenhouse transition. Our models show that tremolite, a hydrous silicate, is a marker of past low-pressure conditions. Models with initial habitable conditions produced substantial tremolite, but models representing a Venus that was never habitable produced no tremolite. Past kinetic experiments demonstrate that tremolite can survive Venus's current conditions (470°C surface temperature, 92 bar surface pressure) and remain stable over long periods of geologic time at those conditions. Therefore, detecting tremolite by future missions could be evidence of a past clement environment with stable liquid water. To validate these outputs, we show that our model can reproduce the present-day atmospheric composition of Venus. The evolution of oxygen fugacity with increasing surface temperatures converges with the present-day value (10^-20 bar) at current temperatures. Modeling the alteration of a habitable Venusian surface during a runaway greenhouse transition can reproduce current atmospheric observations and provide measurable evidence of past habitable conditions.
Upgoer 5 (1:00pm - 1:30pm):
Veronica Fula Big brain computer looks at pictures of ice to find air
Old ice has stuck air that gets long. We can see ice moving direction from where long air is pointing. I am looking for where long air is pointing using a computer that learns what edges are. This is to find more old ice to know about if our very far past was hot.
Emma Heitmann Some Like It Hot!
There are tiny balls all around us, too small to see, and some are light and some are heavy. When it's cold, the heavy balls like to hold hands with other heavy balls. When it's hot, the light and heavy balls will hold hands with any balls that are near them.
Jonathan Lindenmann Can I look at more rocks, and faster?
Looking at rocks under a microscope gives you a lot of information about their history. To use this information for research, hundreds to thousands of grains need to be counted, measured, described, and logged. It's a lot of work! With some statistics and a bit of code, we can give computers a way to look at the microscopic pictures of rocks and decide which mineral is in each part of the picture by creating what's called a *machine learning model*. One way to do it works like this: we label some minerals in pictures and give the labeled pictures to the model. It uses that information as its knowledge about what minerals should look like in similar pictures. Then, we test its knowledge by giving it more pictures that we labeled secretly. This lets us see how good the model is at labeling that picture. With some tweaking, you can make a model that is reliable enough to save you a lot of time. Many researchers do this kind of work as part of their research, but they all have different rocks, and different questions. Luckily, these statistical models that do machine learning can be adjusted in a lot of ways to fit many different needs. We're going to train the model using some thin sections of rocks from the Grand Canyon. These were collected by Nicole Aikin and she wants to look at them more closely in order to figure out how rocks near each other in space are similar, and how they are different. In particular, she wants to know how pressure, temperature, and time affected the rocks in different ways. We can use a machine learning model to label the pictures of her rocks and give us a good idea of how much of each mineral is in each picture, and in each rock. Nicole can use that information to limit the pressure and temperature ranges that the rocks could have formed in. And *that* information is interesting for even bigger questions, like how the middle crust reacts to mountain building. Another way to teach a model to look at these pictures is to train it to figure out what it looks like when one mineral touches another mineral. This model doesn't just look at the color of the pixel, it also looks at the colors of the surrounding pixels to see how they are different from each other. By making a map of all the boundaries between minerals, it can tell you a lot about the shapes, sizes, and relationships between the minerals in the picture. We'll also look into doing this using another model called a convolutional neural network. We'd like this project to be a useful example for others to expand on so that it becomes easier for scientists to look at *more rocks faster*.
Tamara Aranguiz Open cracks
TBD
Geomorphology, Sedimentology, and Paleontology (1:45pm - 3:00pm):
Erich Herzig Modelled Landslides from Multiple Seattle Fault Earthquake Scenarios
An earthquake on the Seattle Fault could induce thousands of landslides. To better understand what controls how many landslides are induced by a Seattle Fault Earthquake, and where landslides are induced, we model landslide probability after 18 distinct earthquake scenarios under both wet and dry conditions. We model both shallow translational failures and deep-seated rotational failures. We find that most scenarios result in similar amounts of landsliding, with many more translational landslides than rotational landslides being induced. We also compare these model results with modern precipitation induced landslide inventories and hazard zones and find general agreement. There are slight differences between scenarios, such as wet conditions leading to more landslides, though these differences are minor.
Paul Morgan Landslide dam susceptibility in the Oregon Coast Range
When a landslide impacts a river, it may form a dam that blocks the flow of water and creates a lake upstream of the slide deposit. While this growing lake may flood roads or infrastructure, the often larger danger lies in the possibility that the lake can overtop in a sudden outburst, draining rapidly and possibly catastrophically. We present a novel workflow using geomorphic measurements and landslide inventories to assess landslide dam formation susceptibility along Oregon Coast Range rivers. Our results highlight susceptible stretches at a regional hazard level. Our results also highlight the impact of bedrock geology, and local relief in controlling valley width and thus river damability.
Tristan Bench Novel Exposure Dating Trials using Optically Stimulated Luminescence
Optically stimulated luminescence (OSL) exposure dating is opening new horizons for late Quaternary dating applications, offering the ability to date <10^2-10^4 year exposed rock surfaces of archaeological, geological, and forensic significance. The framework of the dating technique calculates an exposure age from the shape of OSL versus depth trends measured from rock surface cores, which are correlated to parameters for subsurface light attenuation and a simplified luminescence bleaching rate. The exposure dating technique is still fairly novel, and faces sampling limitations and data resolution issues. For application, it is required that separate, proximal known age rock surfaces are available to parameterize the attenuation and OSL bleaching rate properties for a rock surface of an unknown age, yet such surfaces are commonly absent at sampling sites. Even with successful surface calibrations, however, the millimeter data resolution of depth profiles, offered from wafer slice OSL measuring techniques, prevents precise age calculations, limiting the dating technique’s viability. In response, alternative measuring and sampling protocols are trialed on 11-year exposed surfaces from Lane Mountain Quarry, WA, to address the sampling and measuring challenges for the dating technique. This includes the use of lab-controlled surface exposed samples for rock surface parameter calibration, to eliminate the need for known age rock sources on site for dating, as well as the use of spatially resolved OSL laser scanning for depth profile measurements to attempt producing more resolute OSL depth profiles. In the trial applications, the use of spatially resolved OSL measurements improved the resolution of depth profiles and precision of parameterizations for exposure dating. However, samples with higher OSL intensities are needed to determine the viability of using controlled exposure experiments for rock surface parametrization. Continued geological dating applications using these techniques are planned to better understand and improve upon the limitations of the dating method.
Jacqueline Silviria An exceptional mammal locality from the first ~28 Kyrs after the Cretaceous-Paleogene mass extinction in northeastern Montana
The impact of the Cretaceous/Paleogene (K/Pg) mass extinction event (66.052 Ma) on mammalian evolution is best known from the Western Interior of North America, particularly the Hell Creek region of the western Williston Basin, northeastern Montana. However, the ‘early disaster’ subphase of faunal recovery, spanning the first ~28 kyr after the K/Pg event, remains poorly understood. Here we provide updated biostratigraphic and lithostratigraphic context for the Constenius Locality, an extremely productive vertebrate microfossil site within a sandstone channel from the lowermost Fort Union Fm (Tullock Mbr), just above the uppermost Hell Creek Fm. We hypothesize that the channel was deposited between equivalents of the Iridium Z coal (IrZ) at the K/Pg boundary and the McGuire Creek coal (MCZ; 66.024 Ma). The mammalian local fauna (>400 specimens from at least 13 morphospecies) includes multituberculates (Cimexomys, Mesodma, Stygimys, Valenopsalis), metatherians (Thylacodon), and eutherians (Baioconodon, Mimatuta, Procerberus, Protungulatum, Oxyprimus) typical of the Pu1 interval zone of the Puercan North American Land Mammal Age (NALMA; ~66.052-65.820 Ma). We have also identified metatherian (e.g., Alphadon, Pediomys) characteristic of the preceding Lancian NALMA (~69-66.052 Ma), as well as undescribed cimolestid and leptictid morphs resembling Lancian taxa. In this respect, Constenius resembles Z-Line Quarry, a Williston Basin ‘early disaster’ local fauna constrained between the IrZ and MCZ coals However, the Constenius local fauna is noticeably richer and represented by more complete elements (e.g., dentulous jaws). Additional geochronological and lithostratigraphic work is underway to further bracket the age of the Constenius channel and to rule out reworking as explanation for the Lancian-aspect mammals. Overall, the taxonomic composition of the Constenius local fauna corroborates previous hypotheses of a relatively rapid turnover of North American mammalian communities across the K/Pg boundary. Compositional differences between Constenius and Z-Line may indicate regional heterogeneity in faunal recovery within the Williston Basin.
Tamara Aranguiz Investigating the hyperarid climate and Holocene activity along the Salar Grande Fault, northern Chile, using IRSL dating in alluvial deposits
Deserts record geomorphic, tectonic, and climatic processes in striking detail. The Atacama Desert of South America, considered the oldest and driest desert on Earth, showcases inherited relief that has persisted without major changes since the onset of hyperaridity ~25 Ma. Although a desert climate persists, recent research suggests that hyperaridity fluctuates with humid episodes that increased erosion and deposition during periods of the Neogene suggested by cosmogenic nuclide dating from flat surfaces. Luminescence dating from hillslope deposits also suggests that these punctuated times of erosion persisted during the Late Pleistocene. However, drawing conclusions about the origin and climatic nature of hillslope deposits can be difficult because they can result from the availability of water and/or tectonic activity. To elucidate the origin and timing of increased depositional activity in the hyper-arid core of the Atacama, we collected samples in alluvial fans and colluvial wedge deposits on the foothills of the Coastal Range bounded by the Salar Grande Fault (SGF). We present eight new infrared stimulated luminescence (IRSL) dates spanning from ~40 ka - 2.5 ka. The most insightful results come from the contrasting ages of samples from an alluvial deposit with evidence of distributed deformation parallel to the SGF (6.9 ± 0.63 ka) and a neighboring alluvial fan with nondeformed deposits (3.55 ± 0.45 ka). We interpret these ages as a timing constraint of a paleoseismic event from the SGF, that produced distributed deformation near the epicenter characterized by open cracks and thrusting on alluvial fans near the fault. Our findings unravel the Holocene activity of the Salar Grande Fault reclassifying this fault as active for seismic hazard, rather than just speculated in the current database of Chile, and suggest that the core of the Atacama has been tectonically and climatically dynamic during the last 10 ka.
Keynote Address: 3:30 PM - 4:50 PM (JHN 102)
Guest Speaker : TBD
Poster Session (9:30am - 11:30am):
Fikri Roslan Could enhanced rock weathering sequester CO2 and reduce the hazard of naturally occurring asbestos downstream of the Swift Creek Landslide (Whatcom County WA)?
The Swift Creek Landslide is an active, slow-moving, deep-seated landslide in altered ultramafic rocks of Sumas Mountain in Whatcom County, Washington. Previous workers have estimated that the landslide deposits approximately 120,000 cubic yards of sediment annually into Swift Creek. Other prior work estimates that up to 50% of the suspended sediment introduced into the creek is chrysotile, a naturally occurring asbestos, posing a significant threat to the nearby community. Separately, Washington State’s commitment to reducing greenhouse gas emissions motivates investigation strategies sequester CO2 from the atmosphere or point sources, including enhanced rock weathering (ERW) of ultramafic and mafic rock to produce carbonate minerals. Typically, ERW requires mining and milling to produce fine sediment to provide surface area for the weathering reactions which remove CO2 from the atmosphere. These mining activities reduce the net sequestration potential of ERW. At the Swift Creek Landslide, very fine ultramafic sediments are naturally produced. This study aims to explore the potential utilization of sediment from the Swift Creek Landslide for geologic carbon sequestration. We model the weathering of chrysotile under a range of conditions to examine the potential annual sequestration capacity of SCL sediments. The approach presents a prospective strategy for mitigation of the asbestos hazard while concurrently addressing the pressing issue of climate change.
Kunmanee Bubphamanee Paleozoic deep ocean oxygenation: a record from shale-host selenium isotope analysis
The biodiversification of early benthic animals during the Ediacaran-Cambrian period coincided with the second rise of atmospheric oxygen levels. It has been suggested that deep ocean oxygenation may have been crucial for the evolution of complex animals with a large body plan. However, the paleontological evidence shows that early vertebrate fossils predominantly inhabited shallow water environments and did not diversify in the deeper setting until the late Devonian, challenging previous assumptions. Here we investigate the redox conditions driven by the oxygen contents in the deep waters during the Paleozoic (541 to 252 million years ago) by analyzing the selenium (Se) isotopic values in organic-rich shale. The isotopic signature of non-quantitative Se oxyanion, which preferential sequester light Se isotope (δ82Se <0‰), serves as a proxy for the large reservoir of Se oxyanion in a well-oxygenated deep ocean. In this study, we analyze approximately 100 samples to measure the Se isotope composition using the multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS). Our recent findings reveal an interval of negative δ82Se values during the Ediacaran-Cambrian transition. Then, the trend returns to a crustal δ82Se value during the late Cambrian-early Devonian period, persisting with a negative value after the late Devonian period. This compilation shows a period of deep ocean anoxia facilitating quantitative Se oxyanion during the late Cambrian to early Devonian, which may have constrained the diversification of early vertebrates in shallow water environments. This timing of redox changes may help elucidate the key biogeochemical cycling that protracted deep ocean oxygenation and delayed the diversification of complex life.
Jaimi Lutes Middle Miocene Climate and Landscape Stability in the Pacific Northwest
As the climate changes, we are beginning to see the impacts on a global scale. In order to understand how our landscapes will change with future warming, we can look back to see how landscapes were impacted by past warm, variable climates. This project looks to understand how climate variability in the Middle Miocene is expressed in terrestrial sedimentary records. Using X-ray fluorescence (XRF) analysis, we created a high-resolution elemental geochemical profile of sediment samples from Clarkia, ID. From XRF, elemental concentrations for a host of elements, including Ca, Fe, K, Mn, Sr, Ti, Zn, and Zr, were calculated. Some elements, notably Ca, showed long-term trends but also sections of shorter-term cyclic variability. It is possible that this variability reflects changes in basin weathering rates of Ca-bearing minerals as a function of climate change occurring on tens to hundreds of thousands of years. Alternatively, Ca concentrations may reflect changes to precipitation of Ca-bearing minerals within the ancient lake, responding to algal productivity. These hypotheses are tested using X-ray diffraction (XRD) to identify minerals and their crystalline structures as well as characterizing the elemental trends from an additional site, Clarkia’s P-40. Understanding the depositional history of the clarkia lakebeds aids our understanding in how climate impacts miocene landscapes.
Jason Ott Microstructural evidence of dislocation creep and diffusion accommodated deformation of glaucophane in a lawsonite blueschist
The rheological properties and mechanisms of deformation exhibited by mafic blueschists are crucial factors influencing the mechanical characteristics of the subducting oceanic crust within subduction zones. Blueschists are commonly found along the plate boundary, ranging from the lower part of the seismogenic zone to depths beneath volcanic arcs, yet the strength of this rock type remains uncertain. Studies of blueschists from exposed subduction zones indicate that they can undergo significant strain, primarily involving the sodic amphibole known as glaucophane. However, it remains uncertain whether this observed deformation is primarily facilitated by dislocation or diffusion processes. In this study, we examine the microstructural and textural features of a naturally deformed lawsonite blueschist obtained from the Catalina Schist on Santa Catalina Island, CA. Utilizing techniques such as electron backscatter diffraction (EBSD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), we analyze the textural and geochemical signatures of deformation mechanisms operative during the subduction history of this exposed sample. The blueschist exhibits a distinct foliation and lineation, predominantly composed of interconnected layers of glaucophane. Microstructural analysis using EBSD reveals evidence of dislocation-mediated deformation, including strong crystallographic preferred orientation (CPO), intra-granular orientation gradients, activation of dislocation motion across multiple slip systems, and the formation of subgrain boundaries. The presence of core-mantle structures suggests subgrain boundary recrystallization, indicating the activity of dislocation creep during the sample's deformation history. Additionally, SEM images and EDS maps reveal evidence of microfractures within the glaucophane, characterized by higher concentrations of Fe and lower concentrations of Al and Mg. Chemical zoning associated with these microfractures suggests the possible involvement of diffusion-mediated deformation processes in this blueschist. By integrating textural, chemical, and pressure-temperature (P-T) estimates for the phases and mélange hosting the sample, we infer insights into its deformation history during both subduction and subsequent exhumation phases.
Lucas Fifer Experimental Measurements of Gas Exsolution under Enceladus Conditions
On Saturn’s moon Enceladus, geyser-like eruptions of gas and ice spew into space, providing an opportunity to measure their composition. This plume is thought to originate from a global subsurface ocean, and thus is an important proxy for the composition of this otherwise inaccessible ocean. While molecules in the plume can indicate their presence in the ocean, the exact abundances in the plume do not necessarily reflect those in the ocean due to fractionating processes that occur during eruption. One such process is the differential exsolution of gases from the ocean. As dissolved gases exsolve and water evaporates due to the low pressure environment around Enceladus, the exsolution fluxes will be determined by both the concentrations in the ocean and the coefficients of mass transfer across the ocean-plume boundary. These coefficients of mass transfer can vary between molecules (e.g., hydrogen versus methane) and also with the rate of mixing in the ocean. In this work, we use a laboratory analog of the ocean-plume transition to experimentally measure rates of mass transfer during exsolution. Importantly, we seek to derive the coefficients of mass transfer under the low-temperature, low-pressure conditions that are relevant to Enceladus because mass transfer coefficients for gas exsolution are typically defined and measured under conditions relevant to atmosphere-ocean exchange on Earth. However, we find that exsolution rates under vacuum conditions are generally consistent with those under atmospheric pressure, and that the presence of dissolved NaCl has a negligible effect on gas exsolution. We also measure the effect of stir rate on exsolution, and find increasing exsolution rates with stirring. These results can be used to better constrain models of the chemical fractionation processes during eruption, and thus to better estimate Enceladus's ocean composition from plume measurements.
Leigh Tucker Using Garnet Inclusions to Identify Shared Provenance for Garnet in Washington Coast and Puget Sound Beach Sands
Several beaches along the northern Washington Coast contain garnet-bearing sands, but the source of these garnets is enigmatic. As garnets form they can trap small inclusions of other minerals that record information about the tectonic setting under which the garnet was formed, such as subduction zones or areas of regional metamorphism. Previous results show that inclusions from garnets collected on the outer coast of Washington demonstrate pressure-temperature conditions associated with regional metamorphism, indicating that those garnets were not produced by Cascadia subduction processes. The North/British Columbia Cascades, however, have experienced significant regional metamorphism and are a potential source. If that is the source, how did the garnets get to the coast? Garnet inclusions could be used as a tracer to help identify the source and transport mechanism of these sands, revealing information about glacial and fluvial transport. Here, I test the hypothesis that garnet inclusions in sands found on Puget Sound beaches have the same composition—and thus come from the same original source rock—as the garnets on the outer coast. If this is the case, the Puget Sound garnet sands may help to trace the path of the garnets, via a combination of glacial and fluvial transport, from the Northern Cascades, through the Puget Sound, and out to the coast. Garnet samples from three Puget Sound beaches have been separated from their matrix and mounted on slides. The slides have been polished to access the interior of the grains, allowing the garnet inclusions to be analyzed with scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS). Ongoing work tests whether Puget Sound garnet beach sands show the same inclusion composition as the coastal garnet beach sands. Beyond investigating the provenance of Washington garnet sands, this study further develops the use of garnet inclusions as a tracer for detrital sediment provenance.
Madeleine Lucas Joint geomorphic-geophysical analysis of active strike slip faults offshore Oregon
Compilations of high-resolution bathymetry are particularly useful for mapping the seafloor expression of faulting across multiple marine geophysical datasets. In this study, I use newly acquired USGS-NOAA 30-m and 15-m bathymetry compilations of the Cascadia accretionary wedge to conduct a detailed geomorphic analysis of strike slip faulting offshore central Oregon. My analysis of high-resolution USGS-NOAA bathymetry is complemented by deep-penetrating CASIE21 and near-surface USGS seismic reflection profiles of the region. Using these datasets, I have identified a complex system of both active and inactive right-lateral, N-S trending strike-slip faults offshore central Oregon. To characterize the geomorphic expression of this fault system, I map cross-cutting relationships in the seafloor expression of older and younger strike-slip fault structures in the 30-m bathymetry to constrain the evolution of faulting in this region over geologic time. I locate piercing points in the higher resolution 15-m bathymetry where geomorphic features are offset at the seafloor to help constrain fault slip rates and potential changes in slip rate over time. My analysis of near-surface seismic stratigraphy indicates there is evidence of late Quaternary activity on strike-slip faults cutting across older inactive faults, suggesting that the activity of strike-slip faulting has evolved over time and is linked to changes in fault expression at the seafloor. Deep-penetrating CASIE21 seismic profiles provide additional evidence that this fault system extends to greater depths based on changes in subsurface seismic reflectivity. I hypothesize that this system of strike-slip faults assists in the accommodation of transpressional strain from oblique subduction of the Juan de Fuca Plate beneath the North American Plate, consistent with other observations of active margin-parallel, right-lateral strike-slip faults in other regions of the Cascadia margin that have been shown to help accommodate this transpressional strain.
David Ausmus Earliest Paleocene Multituberculate Mammal Occurrences from the Constenius Locality, Garfield County, Montana
The Cretaceous-Paleogene (K-Pg) mass extinction is one of the most important events in mammalian evolution as it was the catalyst for mammals to diversify and fill the ecological holes left by the extinction of the non-avian dinosaurs. This extinction event impacted all groups of mammals, including the multituberculates, one of the longest-lived and most successful clades of Mesozoic and early Cenozoic mammals. The Constenius vertebrate fossil locality is in the lowermost part of the Tullock Member of the Fort Union Formation in Garfield County, northeastern Montana. It is assigned to the Pu1 interval zone of the Puercan North American Land Mammal Age (early Paleocene) and bracketed by radiometric ages of 66.052 – 66.024 million years ago, within 28,000 years after the K-Pg mass extinction. Constenius is a very rich but understudied fossil locality that provides a snapshot of the immediate aftermath following the K-Pg mass extinction. In this study, we used qualitative descriptions partnered with linear measurements to identify 17 lower fourth premolars (p4s) to the lowest possible multituberculate taxon. We recognized three genera of multituberculates, Cimexomys, Mesodma, and Stygimys, that corroborate the assignment of Constenius to the Pu1 interval zone. Further work on this project will include expanding the dataset to include other multituberculate dental specimens, such as upper premolars, and conducting a geometric morphometric analysis with the lower fourth premolar specimens to further confirm taxonomic identifications.
Erik Perkins Connecting the Dots: Searching for Links Between Puget Sound Faults
The Puget Sound in the state of Washington is riddled with a series of faults that all accomadate the state's north-south oriented shortening due to the rotation of the Oregon block into Washington, which is pushed against the backstop of British Columbia's Coast Range. While these faults all accomadate the same sense of stress, and numerous theories have been provided as to how they might link at depth, no known studies have sought to find a kinematic link between these fault systems using geomorphology. In this study, I used the TopoToolbox in MATLAB to search for signs of local deformation, evidenced by knickpoints, knickzones, and tectonic scarps, that could demonstrate a clear kinematic link between the Canyon River, Saddle Mountain, and Seattle Faults.
Veronica Fula Applying the Segment Every Grain Model to Calculate Air Bubble Shapes in Samples of Antarctic Ice
Old (> 4 Ma) ice drilled at the Allan Hills, Antarctica, can help us understand how Earth’s atmosphere has changed in the past. However, the preservation of this old ice depends on ice flow dynamics, possibly including localized shearing, that are difficult to observe. Bubbles in the ice become elongated when the ice around them deforms. Over time, surface tension processes tend to restore bubbles to spherical. Thus, bubbles can indicate the directions of recent or ongoing strain in the ice. We analyze thin/thick section images taken from four samples of Allan Hills ice. The images include information on grain size (size of individual ice crystals) and bubble size, shape, and distribution. We use the Segment Every Grain (SEG) model, a Python package based on the Segment Anything Model developed by Meta, to automatically calculate the sizes and shapes of bubbles in an image. We validate this method by comparing the values it returns with manually calculated measurements. The bubble orientations that we measure show the predominant directions of strain in the ice. Future work will use these data along with models of bubble elongation to estimate the strain rates at the Allan Hills.
Julia Grossman Crustal Faults in Puget Sound: A Proposal to Study Coupled Earthquake and Tsunami Hazards
Many crustal faults underlie the Puget Sound region of Washington State. Despite the significant earthquake and tsunami hazards, no previous studies have coupled earthquake and tsunami sources to investigate their combined impacts. In addition, Black et al. (2023) recently determined that the 923 C.E. Seattle fault earthquake — previously estimated to be between an M7.0-7.5 — was likely as large as an M7.8, and could have been a composite earthquake across both the Seattle and Saddle Mountain faults. Therefore, the tectonic hazards that the Seattle fault presents may be greater than previously realized. I propose to develop 3-D coupled earthquake/tsunami simulations to better understand the time-dependent hazards posed by the Seattle fault in the populated Puget Sound region. I will quantify ground motion and tsunami hazards by simulating earthquake slip and seafloor displacement along the Seattle fault using the spectral-element code SPECFEM3D, a high-resolution regional seismic velocity model, and the tsunami-modeling software ComMIT and GeoClaw. I will analyze ground shaking intensity measures (e.g., peak ground velocity, peak ground acceleration, and spectral acceleration) to determine the severity of earthquake-induced ground shaking and the most at-risk regions. I will also compare the results of my simulations to empirical ground motion prediction equations (derived from global data) to assess their validity. Then, I will examine tsunami travel times, amplitudes, run up, and inundation along Puget Sound area coastlines. In particular, I will conduct a time-dependent analysis of the spatial distribution and arrival times of earthquake ground shaking and tsunami inundation impacting coastal communities. Overall, a better understanding of the spatial and temporal overlap of co-seismic hazards (i.e., shaking and inundation) will have important implications for emergency planning and engineering standards in near-source communities and in the Puget Sound region as a whole.
Emma Heitmann Rise of the Colorado Plateau: Leveraging climate models, stratigraphy, and carbonate clumped-isotope thermometry to disentangle topographic and climatic signals from the Miocene Bidahochi Formation
Uplift of the Colorado Plateau in the southwestern U.S. was a consequential event that impacted regional climate and geomorphic features like Grand Canyon, but the cause of and history of surface uplift is a major focus of debate. This region is ~2 km above sea level today, and models and paleo-elevation estimates hypothesize that the plateau uplifted anywhere from 1.5km to 0km in the past 20Ma. To test these hypotheses, I aim to reconstruct surface elevation from 16-6Ma lake deposits of the Bidahochi Formation on the southwestern Colorado Plateau by using carbonate clumped isotope thermometry to construct a high-resolution surface-temperature (T) record. Depositional surface-T can be related to elevation because air-T decreases systematically with altitude. However, the deposits span a significant period of global climate change and it is estimated that global mean T dropped ~7-10 °C from 16 to 6 Ma. To determine how much regional elevation change the T record permits or requires, we must first understand the effect of coeval climate change. If surface-elevation was equivalent to modern (null hypothesis, H0), I would expect reconstructed T to mirror the timing, direction, and magnitude of global climate changes. Based on a local sea surface T record at a comparable paleolatitude and 1-D calculations of T lapse rates for a range of humidity conditions, I expect 3-5 °C of cooling from 12-6 Ma in the Bidahochi record due to climate change with constant CP elevation. My preliminary data (+/- 10°C 95%CI uncertainty) show a cooling trend across the depositional period that is significantly larger in magnitude than predicted for H0, which - if confirmed - would imply large-scale regional uplift since 15Ma. Here, I present results from climate model simulations to refine predictions for expected T changes under H0 and under different topographic scenarios.
Jonathan Lindenmann Speeding up the petrographic data pipeline with machine-learning-assisted image processing.
When micrographic techniques are applied to rock thin sections, they produce large, data-rich images. By its nature, extracting data from such images is often laborious and error-prone work. With the integration and expansion of machine learning techniques in data science, the task of training a computer to generate those datasets with human accuracy is not only achievable without cost-prohibitive equipment for many use cases, it can also be tailored to different applications. In this project, we develop two machine learning models to produce a label dataset for each thin section that 1) labels each pixel and 2) identifies mineral grain boundaries and 3) provides a comprehensive statistical and graphical overview of the labeled data for further processing. The model will be trained on a manually curated training dataset of pixels with mineral labels from thin sections of samples the Upper Granite Gorge (UGG) of the Grand Canyon, provided by Nicole Aikin’s PhD thesis project. We then test and compare the models and make adjustments to customize them to the desired application of producing detailed compositional data of the UGG samples for PT-space reconstruction. The labeling of individual pixels is achieved with a PCA and random forest model, while grain boundary recognition is modeled using a convolutional neural network. The project code will be publicly available on GitHub with proper documentation to serve as a proof of concept module for an open-source petrographic image-processing platform with robust, research-oriented customization capabilities. This project is in the early stages of progress.