April 3rd, 1:30-4:30pm, JHN 100-level hallway
Gabrielle Alampay: Interpreting Haida Gwaii's Marine Terraces Using LIDAR Data
- In this study, I map and consider possible driving mechanisms of marine terrace formation on the archipelago of Haida Gwaii, Canada. Marine terraces are gently sloping platforms created by wave erosion along shorelines, and are preserved through crustal uplift or sea level change. In the past, native people of the islands occupied areas along the now uplifted shorelines. Archeologists have found artifacts on some of these terraces and have dated them to be ~8,500-9,000 B.P.. Southwest of the islands, there is a young subduction zone, which produced a Mw 7.8 thrust earthquake in 2012 and has been hypothesized to drive uplift in Haida Gwaii. While the islands are ice free today, they hosted an ice cap during the last glacial maximum and were in the forebulge of the Cordilleran Ice Sheet. The islands may have also uplifted from isostatic rebound as a result of the ice melting. To identify the formations, I mapped marine terraces from 1,500 km2 of high resolution elevation topography derived from LIDAR data. In the data, I find terraces throughout the study area that extend up to 18 m above sea level. Typically, only one terrace is preserved and terrace heights are about the same elevation of ~15-18 m across the study area. From this study, we can find out more information about the terraces’ geometry, if there are spatial trends in elevation, size, and distribution in order to further our understanding of what is driving the land uplift. Identifying and studying Haida Gwaii’s marine terraces are important to help archaeologists date known terraces and help geologists better understand the tectonics of the area.
Surabhi Biyani: Estimating the Upper Bound of Crustal Heat Flow under Antarctica
- Geothermal flux, the amount of heat from the Earth’s interior that reaches the Earth’s surface, is an important boundary value used when modeling ice sheets in Antarctica and estimating future sea level rise. However, geothermal flux is difficult to measure directly. This research project used a numerical ice and heat flow model to estimate the upper bound for geothermal flux under ice domes in Antarctica. We applied this model to ice domes with identifiable Raymond arches, structures in the internal stratigraphy which form only when the ice is frozen to the bed. We estimated the geothermal flux at which an ice dome’s modeled basal temperature reaches the melting point, thus setting an upper bound, using site-specific values for the accumulation rate, surface temperature, and ice thickness. Where measured basal temperatures are known, we made more precise estimates of geothermal flux. Uncertainty values for the modeled flux values were derived by testing the uncertainty of each input value. Model estimates were compared with Martos et al. (2017) and An et al. (2015) geothermal flux estimates derived from remotely sensed data. Comparisons show that in regions such as the Siple Coast, estimates disagree significantly, while they mostly agree in the Antarctic Peninsula. The results of this project set an upper limit on geothermal flux values that can be used to support past and future geothermal flux estimates at these locations.
Fred Bradley: Ice Polymorph Formation and Segregation Within High-Pressure Icy Mantles of Watery Moons
- Understanding the subsurface dynamics and differentiation of icy moon interiors is critical for model development, future mission planning, and guiding the search for life beyond Earth. Icy moons such as Enceladus, Ganymede, and Europa contain enormous amounts of water that form kilometers thick icy crusts which cover massive liquid oceans. These waters also likely contain solutes (e.g. MgSO4, NaCl, Na2SO4) leached from the underlying silicate mantles. As a result, the interiors of these icy worlds are thought to be differentiated ocean systems with layers of ices and water whose vertical partitioning is dependent on the relative densities of each phase and decreases in melting temperature with higher salt concentrations. The experiments performed in the ESS mineral physics laboratory at UW determine not only the phase of ice expected at pressures and temperatures found within icy moons but also measures melting temperature depression for each phase as a function of salt complex and concentration. Determination of phase boundaries was measured by manually nucleating ice crystals in a diamond anvil high-pressure cell at a given temperature while ruby fluorescence spectroscopy recorded the corresponding pressure. Samples of pure water, as well as 0.5 molal, 1 molal, and 2 molal concentrations of each salt solution were studied. From in-situ sound speed measurements and X-Ray diffraction data, a local basis function representation of the free energy (Gibbs) was used to calculate and extract thermodynamic data for each aqueous solution and ice phases. These results allow for further exploration and understanding of the behavior of salty waters within the interiors of icy moons. These relationships are important for understanding the spatial distribution and partitioning of ice and aqueous solution phases, the possible geodynamic drivers such as heat transport regime and density contrasts, and predictions about the state of the hydrosphere/silicate mantle boundary.
Cassie Brigham: Examining the causes of degradation of fault scarps in Iceland
Connor Geiman: Designing a Reliable Asteroid Sample Retrieval System
Elizabeth Davis: Evidence for earthquakes from the Duwamish Waterway, Seattle
- The Duwamish Waterway in the city of Seattle provides clues to the city’s earthquake hazards. The industrialized banks of the waterway locally expose intertidal mud of the former Duwamish River estuary. These deposits contain evidence for two earthquakes in the centuries since the large Seattle Fault earthquake of 900–930. (All age ranges are in calibrated years CE at two standard deviations). The evidence consists of intrusions and extrusions of andesitic sand within the mud. These sand bodies were likely produced by earthquake-induced liquefaction of the Mount Rainier lahar-runout deposits that underlie the mud. The earlier of the two inferred earthquakes is evidenced by a sand layer that extends discontinuously for at least 50 m. This layer consists of coalesced sand lenses up to 12 cm thick. The layer coincides with the upper limit of parallel, mostly vertical sand intrusions interpreted as evidence for lateral spreading. The implied earthquake likely dates to 1010–1150, as judged from radiocarbon ages of growth-position Triglochin maritima leaf bases that one of the sand lenses drapes. At least one later earthquake is evidenced by dikes in younger mud. One of these dikes approaches the stratigraphic level of T. maritima leaf bases from 1250–1290. Other dikes nearby were traced up to Bolboschoenus maritimus corms from 1470–1640. None of the injected or erupted sand bodies observed thus far reach the likely stratigraphic level of the 1700 Cascadia earthquake or the Puget Sound earthquakes of 1949, 1965, and 2001. I am grateful for guidance by Brian Atwater, Juliet Crider, and Carrie Garrison-Laney; and for diatom analysis by Eileen Hemphill-Haley.
Gabriel Goncalves: A New Drepanosauromoph Species from the Chinle Formation of Petrified Forest National Park, Arizona
- Drepanosauromorpha is an extinct group of reptiles known from the Middle to Late Triassic (237–212 MA). The clade currently includes seven genera (Avicranium, Dolabrosaurus, Drepanosaurus, Hypuronector, Kyrgzsaurus, Megalancosaurus, and Vallesaurus) that are known from fossils collected in Europe (Italy, UK), North America (Arizona, New Mexico, New Jersey), and Asia (Kyrgyzstan). The first described drepanosauromorph, Drepanosaurus unguicaudatus, was based on a flattened holotype preserving most of a complete skeleton. Subsequently described drepanosauromorphs contain some of the following features: the length of the chevrons is substantially longer than caudal (tail) neural spines, the cervical (neck) vertebrae are heterocoelous (saddle-shaped articular surface), the cervical ribs are absent as distinct ossifications and the chevrons are fused to the centra. In recent years, both three-dimensionally preserved partial skeletons and isolated material of drepanosauromorphs have been found across both Europe and North America. These discoveries have helped shape our understanding of the biology and diversity of drepanosauromorphs. However, comparing isolated, three dimensionally preserved specimens to the more complete, yet two dimensionally preserved articulated specimens is difficult due to differences in preservation. Here, we describe a new drepanosauromorph species from the Chinle Formation in Petrified Forest National Park, Arizona based on the ungual phalanx of the second digit of the hand. Some of the characteristics that distinguish this claw from most drepanosauromorphs is the size of the claw. It differs significantly from all known Drepanosaurus specimens (like the Italian holotype and the Hayden Quarry Drepanosaurus) because of the ventral placement of the cotyle, the height of the claw, the lack of compression along the pre-axial/post-axial plane and a furrow along the midline. This new taxon not only shows how much morphological variation there is within Drepanosauromorpha, but this taxon also helps create a clearer understanding of the evolutionary history of smaller-bodied reptiles within the Triassic.
Logan Guillet: Ice Crater Analysis Using Advanced Surveying Techniques
- This research focuses on using advanced surveying techniques as well as hand mapping to analyze force distribution during laboratory impacts of man-made projectiles into ice. This is done in the hopes of characterizing substrate damage surrounding an impact crater created by a proposed hard landing system. Knowing where these different deformation zones occur is useful in determining where the lander could sample. The landing system, the Subsurface Ice Plume Sampler (SIPS) utilizes ejecta (broken up debris thrown from the crater) to create a transient atmosphere - decelerating a secondary instrument package through momentum transfer. Small-scale experiments were done on one-ton buckets of ice using scale-sized projectiles. Between two hundred and five hundred images used to 3D models of the ice craters using the structure from motion imaging technique. Hand mapping of the deformation zones (areas of different types of fractures) was conducted to compare to the 3D model to help show the directionality of force distributions through the crater. Using both the 3D models and a hand mapping analysis of the craters, we were able to determine that the crater shapes were atypical. In a typical crater, the force disperses radially outward from the impactor; however, we determined that the majority of the force was focalized directly below the impactor. Future work includes using Rhinoceros 3D computer software to quantitatively analyze each crater’s individual morphology, curvature, and volume and compare them to traditional impact craters.
Monica Hill: Constraining Slip Rates Along the Seattle Fault Zone Using Low Temperature Thermochronometry
- The Seattle Fault Zone (SFZ) is a region of complex, east-west striking thrust faults in the Puget Sound area in Washington. Radiocarbon dating of landslides has determined that the SFZ most recently ruptured ~900-930 years ago. At this time, non-glacial sedimentary rocks from the Blakeley Formation (26-37 Ma) were uplifted up to 7 meters along the hanging wall of the fault. In this study, we use low temperature (U-Th)/He thermochronology to constrain the timing and slip of the main thrust of the Seattle Fault Zone. The dating technique is used on apatite crystals from samples of the Blakeley sandstone to develop a time-temperature cooling history as the rocks were uplifted and subsequently exhumed. The apatite (U-Th)/He thermochronometer records the date that the mineral passed through 70℃ closure temperature. Based on a 25℃/km geothermal gradient, this closure temperature represents the upper 2-3 km of the crust. The samples were collected from a transect along the hanging wall of the fault, from Alki Point, Seattle in the west to East Lake Sammamish, Issaquah in the east. All samples were collected between 0.5 and 1 m from the surface, and at similar elevations in order to account for different exhumation rates. The rate of uplift along the fault will be determined by the dates recorded by the apatite thermochronometers, where younger dates indicate more rapid rates. From this data, we will back out erosion rates in order to constrain the total fault movement.
Brita Horlings
Joel Jacobsen: Anthropogenic Influence on Reactive Chlorine in the Troposphere
- Reactive halogens (Cl, Br, I) effect the oxidative capacity of the atmosphere as well as the lifetime of pollutants and greenhouse gases by serving as oxidants directly and indirectly through their impact on the atmospheric abundance of the hydroxyl radical and ozone. Sea-Salt is the largest source of reactive halogens in the troposphere. A global modeling study suggests that anthropogenic activities have increased the abundance of reactive halogens in the troposphere, primarily through an increase in ozone deposition to the ocean surface which reacts with iodide in sea water to release reactive iodine to the troposphere. However, many uncertainties exist in modeling reactive halogen chemistry. Here, we investigate the trends in reactive chlorine over the last 800 years using ice core records of sodium (Na+) and chloride (Cl-). Excess Cl has been found to increase after the beginning of the anthropogenic time period (1850 C.E.). This qualitatively supports modeling studies suggesting larger amounts of reactive Cl due to anthropogenic activities.
Bing Yu Lee: Understanding the Temporal Variation of Methane Seepage at Southern Hydrate Ridge (SHR) using Acoustics
- Methane reservoirs are commonly found throughout the world’s oceans and the release of methane from seafloor reservoirs is thought to make up 5 to 10% of the global atmospheric methane. In fact, the greatest deep-sea mass extinction in the last 97 Myr during the Paleocene-Eocene Thermal Maximum (PETM) may have been caused by methane release from seep sites along the upper continental slope margin. Recently, methane reservoirs along this margin have been gaining attention due to their potential to accelerate current global warming. Changes in seafloor pressure and temperature could destabilize these seafloor deposits and cause methane bubble plume release into the ocean. At SHR, an extensively studied active seep site located ~ 90 km offshore Oregon, discontinuity in methane plume release was observed, but still not well understood. Hence, using Acoustic Doppler Current Profiler (ADCP) and pressure data archived by the Ocean Observatories Initiative (OOI) Cabled Array, we will be investigating the potential correlation between tides and the presence of methane plume at SHR. Our study detects methane plume structures based on the proxies of echo contrast caused by acoustic-bubble interaction. By analyzing the derived plume structures and their correlation with 226 tidal cycles, we expect a trend of plume release triggered by low tides. Our study will provide the first high-temporal-resolution analysis on the methane plume release at SHR using OOI acoustic data.
Joshua Lee: Buildup of Larges Scale Field Test for Asteroid Sampler
- Our current research with the Kinematics and Impacts Lab at the University of Washington entails the design, buildup, and field testing of an asteroid sampling system. These field tests include the buildup of two stage closer rockets, which will be highlighted in this presentation. This asteroid sampler field testing helps characterize the sampling process of impacting an asteroid at high speeds- necessitating our rocket system be capable of stable, high speed flight, even at an inverted trajectory. The booster stage, or primary stage, of the system consists of a single large motor to allow the system to reach between 3000-4000 feet above the ground. The sustainer, or second stage, consists of eight smaller motors clustered around a central body tube, allowing the second stage to be hollow. Finally, a hollow point steel nose cone caps the sustainer. Inside the nose come assembly a sample dive is attached, designed to eject during impact. Field testing of this system occurred in December 2018, with preliminary results being compiled.
Alex Lowe: A project proposal: Ancient plant community and climate of the Pacific Northwest (USA) during the Middle Miocene Climatic Optimum
- The MMCO occurred ~17–14 Ma, is one of Earth’s most recent transient warming events, and may constitute our best modern analog for a warm Earth. Currently, the response of regional vegetation and climate to the MMCO in the western U.S. remains enigmatic, as previous studies utilizing different paleobotanical records arrive at conflicting inferences. For example, phytolith records suggest an open-habitat grassland – woodland mosaic persisted in Idaho from ~23–15 Ma, characterized by arid to sub-arid climates. In contrast, macrofossil records from other Pacific Northwest localities suggest that broadleaved evergreen forests spread northward to ~45 °N, following warmer, wetter, and seasonally milder climates. Comparing reconstructions from different proxies involves several confounding factors that are difficult to disentangle, including age differences, regional-specific factors (e.g., topography), and what ecological information is captured by each paleobotanical record. This collaborative project will avoid such confounding comparison by integrating plant microfossils (i.e., pollen/spores and phytoliths) and macrofossils (e.g., leaves) from eighteen PNW fossil sites that represent before, during, and after the MMCO. Fossil information will be placed into a refined temporal framework by high precision radiometric dating of interbedded tuffs. Aspects of the ancient plant community ecology will be assessed including relative abundance, diversity, leaf life span, habitat openness, and spatial heterogeneity. Climatic estimates will be developed using leaf physiognomic methods and co-existence analysis, the latter which considers the overlapping climatic tolerances of the fossil’s nearest living relatives. All these data will be integrated to assess temporal and spatial patterns in PNW climatic and vegetational response across the MMCO, and to provide insights critical to predicting the long-term effects of current anthropogenic warming.
Zack McIntire: On the Hydrodynamics of Crystal Clustering
- The formation of crystal clusters may influence the mechanical behaviour of magmas. However whether clusters form largely from physical contact in a mobile state during sedimentation and stirring, or require residence in a crystal mush is not well understood. We use discrete-element fluid dynamics numerical experiments to illuminate the potential for clustering from both sedimentation and open-system mixing in a model olivine basalt reservoir for three different initial solid volume fractions. Crystal clustering is quantified using both bulk measures of clustering such as the R index and Ripley's L(r) and g(r) functions and with a variable scale technique called Voronoi tessellations, which also provide orientation data. Probability density functions for the likelihood of crystal clustering under freely circulating conditions indicates that there is nearly an equal likelihood for clustering and non-clustered textures in natural examples. A crystal cargo in igneous rock suites exhibiting a dominance of crystal clusters may be largely sampling magmatic materials formed in a crystal mush.
Megan Mueller: Post-Collisional Evolution of Western Anatolia: Tectonostratigraphy of the Saricakaya Basin
- Anatolia is a complex mosaic of terranes that collided from the late Cretaceous through the Paleogene. In western Anatolia, the most significant collision occurred between the Sakarya Zone of the Pontide terrane and the Tavsanli Zone of the Tauride-Anatolide Platform. At least 700 km convergence since 90 Ma was facilitated by the subduction zone(s), today marked by the >1700 km long Izmir-Ankara-Erzincan suture. Despite the large volume of work on the numerous Anatolian terranes and collisions, basic questions regarding the onset of subduction, number and polarity of subduction zones, timing of collision, style of post-collisional deformation, and development of topography and fold and thrust belts remain enigmatic. Here, we discuss early fold-and-thrust belt development of the western Anatolian orogeny through the stratigraphic and sedimentologic evolution of the Saricakaya Basin. This basin is a small, poorly-studied sedimentary basin between the Izmir-Ankara Erzincan suture zone and basement-involved Söğüt Thrust fault, and exposes a thick, Eocene sedimentary sequence thrusted by post-collisional orogenic build-up. New age constraints from zircon U-Pb dating of volcanic deposits, and new data from U-Pb detrital zircon geochronology and sedimentary facies reveal changes in provenance and depositional environments related to the post-collisional evolution of the suture zone. We show that the Saricakaya Basin is an Eocene post-collisional wedge-top basin created by loading from the Söğüt Thrust, and the depositional environments record periods of thrust building and quiescence. Unlike the thin-skinned fold-and-thrust belt of central Anatolia, the Saricakaya Basin documents an along-strike change in deformation style and orogenic evolution.
Haley Redinger: A Comparison of Growth Strategies by U-reducing Bacterium Shewanella putrefaciens CN32
- Widespread distribution of dissolved uranium (U) from natural and anthropogenic sources poses a challenge to both environmental and human health. Some bacteria are known to reduce highly soluble U(VI) into more stable U(IV), limiting the rate it may leach into subsurface environments. Therefore, understanding how this metabolism functions in situ is vital for predicting subsurface U transport. Any thorough understanding of microbial metabolisms must compare different means of energy production (i.e. catabolic reactions). This means the metabolic processes involved in U(VI) reduction must be compared to those where an alternative terminal electron acceptor (TEA) is used. The facultative anaerobic bacterium Shewanella putrefaciens strain CN32 has the focus of many recent studies on U, but there has yet to be a detailed study of its metabolic efficiency across multiple TEA’s. This work quantitatively examined the metabolic efficiency of Shewanella putrefaciens CN32 by comparing the ratio of cells produced to the total mass of protein produced when growing on three different TEA’s: O2, Fe(III), and U(VI). Furthermore, the overall health of the culture was evaluated by measuring the size of cells grown with each TEA. Initial results indicate that both a larger average cell size and larger ratio of cells to protein mass correspond with potential Gibbs energy of each catabolic reaction (in decreasing order: O2, Fe(III), U(VI) reduction). Gaining a further understanding on bacterial U reduction will allow for hazard mitigation methods to be developed and used in at-risk areas around the world.
Nicole Sarieddine: Determining the month of soil carbonate formation for paleoclimate reconstruction
- Carbon dioxide concentrations have been on the rise since preindustrial times due to anthropogenic emissions. Understanding how past climates have responded to changes in the atmosphere is important to understand how our current climate will react to changes in our present-day atmosphere. Soil carbonates record the temperature at the time of their formation in their stable isotopic composition (called clumped isotope geochemistry). Ancient soil carbonates can record the temperature and allow us to better understand paleoclimates. Understanding what time of year soil carbonates form allows us to better interpret the temperature being recorded. The timing of changes in soil moisture is likely one of the most important environmental factors to consider. We test whether soil carbonates form during soil drying events using soil moisture and temperature data measured remotely by a satellite called Soil Moisture Active Passive (SMAP). This satellite has been gathering near-surface soil moisture data globally since 2015 at 35-65 km resolution. We compare the air temperature of the month with the greatest net negative soil moisture content month (determined from the satellite data) to the measured growth temperature of soil carbonates (estimated through geochemistry). We first compare the month of drying of three locales in North America, then extend the analysis globally to all locations for which soil carbonate clumped isotope data exist. Preliminary results suggest that the temperature of the month with the most drying agrees with formation temperature we estimated from clumped isotope geochemistry within one degree for a site in Nebraska and within seven degrees for a site in Wyoming. These results suggest that soil drying promotes soil carbonate formation in some environments. By using soil carbonates to explain past climates, we will improve temperature change estimates, which will help improve climate models for the future.
Kelsay Stanton: Tectonic implications recorded by Pleistocene and older marine terraces above the Cascadia Subduction Zone, Willapa Bay, Washington
- What is the record of subduction-related deformation at the timescale of a million years? Pleistocene and older marine terraces up to 400 feet above sea level near Willapa Bay, southwestern Washington may provide insight to the mechanism and timing of deformation above the Cascadia Subduction Zone. GIS analyses of terrace surfaces and detailed mapping will provide geological and structural information about terrace sets previously mapped as a single unit. Dating of terrace sediments will provide estimates of terrace ages and uplift rates. Comparison of terrace uplift rates around Willapa Bay can suggest a mechanism of uplift. If uplift of a given terrace is approximately the same north to south along the coast, I infer that most uplift has been from unrecovered elastic strain related to subduction. If the uplift of a given terrace is remarkably different north to south, faults and folds in the North American plate may be causing deformation.
Max VanArnam: Modeling Monsoon Flood Erosion in the Eastern Himalaya: using HEC-RAS to simulate velocity and depth for high discharge annual flows
- When seeking to better understand specific bedrock river erosional processes due to flooding, numerical modeling can help answer many questions, specifically the extent to which floods contribute to setting the landscape. The eastern Himalaya experiences multiple flooding events of different magnitude: annual monsoon floods (10^3 m3/s) and centennial outburst floods (10^5 m3/s). This region also experienced at least two ancient megafloods during the Holocene (10^6 m3/s). Previous studies of flooding in the region have assessed the potential geomorphic role of the outburst floods and megafloods; however, the relative geomorphic impact of annual monsoon flooding remains unknown. To fully understand the relative erosive power of these eastern Himalayan floods, it is necessary to compare the hydraulics of outburst dam-break floods to the hydraulics of seasonal monsoon flow. To do this, we will use HEC-RAS to numerically simulate monsoon flood flow in this region. We can analyze patterns of flow velocity and depth (HEC-RAS outputs) to understand the spatial pattern of shear stress during monsoon floods. We expect to find that monsoon flow will yield lower magnitudes of shear stress and more homogeneous patterns of potential erosion compared to those observed for the outburst floods and megafloods. Understanding these erosional spatial patterns will help us better recognize the relative contributions of various magnitude floods and the extent to which each can set the landscape.