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Articles 31 - 60 of 507

Full-Text Articles in Geology

Investigating Geomorphic Controls On The Luminescence Properties Of Quartz Sand In A River System, Jenna Mills Apr 2024

Investigating Geomorphic Controls On The Luminescence Properties Of Quartz Sand In A River System, Jenna Mills

Student Research Symposium

Optically Stimulated Luminescence (OSL) dating of quartz sand grains is used to date young deposits across disciplines in geology and archaeology. OSL dating requires that the quartz mineral is sensitized, or pre-conditioned to produce a luminescence signal following exposure to ionizing radiation. The geological processes that enhance the OSL sensitivity (photons released per given radiation dose and sediment mass) remain uncertain. Our Research Objectives are to investigate the geomorphic controls (bedrock source, fluvial transport, and hillslope processes) on OSL sensitivity using sediment collected along the Pagliara River in NE Sicily.

The Pagliara catchment (13km2) is tectonically active and …


Implications And Hydrographs For Two Pre-Bonneville Pluvial Lakes And Double Geosols From 14 Osl-Irsl Ages In Cache Valley, Ne Bonneville Basin, Robert Q. Oaks Jr., Susanne Jänecke, Tammy Rittenour, Thad Erickson, Michelle Nelson Jan 2024

Implications And Hydrographs For Two Pre-Bonneville Pluvial Lakes And Double Geosols From 14 Osl-Irsl Ages In Cache Valley, Ne Bonneville Basin, Robert Q. Oaks Jr., Susanne Jänecke, Tammy Rittenour, Thad Erickson, Michelle Nelson

Geosciences Faculty Publications

In the northeastern Great Basin, USA, thirteen new optically stimulated luminescence (OSL) ages and one infrared stimulated luminescence (IRSL) age show that two deep pluvial lakes preceded the Bonneville lake cycle in Cache Valley during marine oxygen-isotope stages (MIS) 6 (213-191 ka) and 4 (56-71 ka), respectively. Our new data define quantitative hydrographs of the Little Valley and Cutler Dam lake cycles in both Cache Valley and the main Bonneville basin. In western Cache Valley, excavation of a faulted, east-plunging spit has sequentially exposed these deposits and overlying MIS 3 Fielding humid-over-arid double geosols that end westward at a strand …


Cambrian Trilobites From The Nounan Dolomite And Lower St. Charles Formation (Upper Marjuman To Lower Sunwaptan; Miaolingian To Furongian Series), Smithfield Canyon, Northern Utah, Frederick A. Sundberg, Hannah R. Cothren, Carol M. Dehler Jan 2024

Cambrian Trilobites From The Nounan Dolomite And Lower St. Charles Formation (Upper Marjuman To Lower Sunwaptan; Miaolingian To Furongian Series), Smithfield Canyon, Northern Utah, Frederick A. Sundberg, Hannah R. Cothren, Carol M. Dehler

Geosciences Faculty Publications

The trilobite faunas that occur with the Steptoean Positive Isotope Carbon Excursion (SPICE) at Smithfield Canyon, Utah, have been reported, but not illustrated. Given the importance of the SPICE at this section for international correlations, the trilobites from new collections from the upper Nounan Dolomite to lower St. Charles Formation at Smithfield Canyon are reported herein and integrated with the previously reported taxa. Trilobite assemblages indicate that the upper Cedaria to the Ellipsocephaloides biozones (Miaolingian Series, Guzhangian Stage to Furongian Series, Jiangshanian Stage) are present stratigraphically below or above the SPICE.

Some of the taxa reported herein may represent new …


Constraining Silicate Weathering During The Middle Eocene Climatic Optimum (Meco) Using Radiolarian Ge/Si, Olivia R. Laub Dec 2023

Constraining Silicate Weathering During The Middle Eocene Climatic Optimum (Meco) Using Radiolarian Ge/Si, Olivia R. Laub

All Graduate Theses and Dissertations, Fall 2023 to Present

Silicate weathering has long been considered a fundamental component of the earth system and has been cited as one of, if not the primary stabilizing feedback for climate. However, recent work has shown that the role of silicate weathering in the climate system is more complicated and dynamic than previously assumed. In this study I examine the role of weathering in the enigmatic warming event, the Middle Eocene Climatic Optimum (MECO) that occurred approximately 40 Ma. This event works as a good case study as there are multiple features of the MECO that differentiate it from other warming events that …


Tropical Atlantic Temperature And Hydrologic Shifts During The Paleocene-Eocene Thermal Maximum, Chels Howard Dec 2023

Tropical Atlantic Temperature And Hydrologic Shifts During The Paleocene-Eocene Thermal Maximum, Chels Howard

All Graduate Theses and Dissertations, Fall 2023 to Present

The Paleocene-Eocene Thermal Maximum (PETM) is a geologic climate event that is studied heavily due to the similarities to anthropogenic climate change. This event occurred approximately 56 million years ago (Ma) and is characterized by a rapid release of carbon into the atmosphere, which resulted in an increase in temperature and a change in global climate events such as changes in patterns of evaporation and precipitation. We see this effect occurring in modern anthropogenic climate change due to the burning of fossil fuels releasing carbon dioxide (CO2) into the atmosphere. In this study I use elemental data of …


Geothermal Play Fairway Analysis, Part 1: Example From The Snake River Plain, Idaho, John W. Shervais, Jacob Deangelo, Jonathan M. Glen, Dennis L. Nielson, Sabodh Garg, Patrick Dobson, Erika Gasperikova, Eric Sonnenthal, Lee M. Liberty, Dennis L. Newell, Drew Siler, James P. Evans Nov 2023

Geothermal Play Fairway Analysis, Part 1: Example From The Snake River Plain, Idaho, John W. Shervais, Jacob Deangelo, Jonathan M. Glen, Dennis L. Nielson, Sabodh Garg, Patrick Dobson, Erika Gasperikova, Eric Sonnenthal, Lee M. Liberty, Dennis L. Newell, Drew Siler, James P. Evans

Geosciences Faculty Publications

The Snake River Plain (SRP) volcanic province overlies the track of the Yellowstone hotspot, a thermal anomaly that extends deep into the mantle. Most of the area is underlain by a basaltic volcanic province that overlies a mid-crustal intrusive complex, which in turn provides the long-term heat flux needed to sustain geothermal systems. Previous studies have identified several known geothermal resource areas within the SRP. For the geothermal study presented herein, our goals were to: (1) adapt the methodology of Play Fairway Analysis (PFA) for geothermal exploration to create a formal basis for its application to geothermal systems, (2) assemble …


Shallow Composition And Structure Of The Upper Part Of The Exhumed San Gabriel Fault, California: Implications For Fault Processes, Kaitlyn Crouch, James P. Evans Sep 2023

Shallow Composition And Structure Of The Upper Part Of The Exhumed San Gabriel Fault, California: Implications For Fault Processes, Kaitlyn Crouch, James P. Evans

Geosciences Faculty Publications

Quantifying shallow fault zone structure and characteristics is critical for accurately modeling the complex mechanical behavior of earthquakes as energy moves within faults from depth. We examine macro- to microstructures, mineralogy, and properties from drill core analyses of fault-related rocks in the steeply plunging ALT-B2 geotechnical borehole (total depth of 493 m) across the San Gabriel Fault zone, California. We use macroscopic drill core and outcrop-sample analyses, core-based damage estimates, optical microscopy, and X-ray diffraction mineralogic analyses to determine the fault zone structure, deformation mechanisms, and alteration patterns of exhumed deformed rocks formed in a section of the fault that …


Volatile Cycling And Metasomatism In Flat-Slab Subduction Zones Of The Central Andes, Coleman Hiett Aug 2023

Volatile Cycling And Metasomatism In Flat-Slab Subduction Zones Of The Central Andes, Coleman Hiett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Flat-slab subduction, where an oceanic plate subducts horizontally below a continental margin for hundreds of kilometers, is an enigmatic but prevalent tectonic configuration in which chemical cycling and alteration of the continental plate is poorly constrained. Geochemical investigations in regions of modern and ancient flat-slab subduction in the Central Andes afford an opportunity to study this process. Certain elements naturally occur with varying number of neutrons in their nuclei (isotopes), and measurements of isotope ratios within geologic materials inform on chemical sources and geologic processes. This research leverages stable isotope analyses and other geochemical tools to investigate volatiles and other …


Igneous Petrology Of Rumicolca Lavas From The Peruvian Altiplano: Controls On Compositional Variability And Source Characteristics, Jacob Ladner Apr 2023

Igneous Petrology Of Rumicolca Lavas From The Peruvian Altiplano: Controls On Compositional Variability And Source Characteristics, Jacob Ladner

Student Research Symposium

Lava flow samples from the Peruvian Altiplano plateau described petrologically, mineralogically, and geochemically for investigation of of genetic relation, compositional variability, and melt source characteristics. Reflective of a metasomatically altered mantle resulting from subduction of the Nazca plate under the western margin of South America.


Late Pleistocene Piedmont Records In The Grand Staircase Region, Southern Utah, Alexander K. Short Dec 2022

Late Pleistocene Piedmont Records In The Grand Staircase Region, Southern Utah, Alexander K. Short

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Today the climate in the southwestern United States is arid, characterized by desert landscapes and habitats, periods of drought, and arroyo streams that frequently fill with, and erode, through fine riverbed sediments. A series of cliffs and benches rising from the Grand Canyon to the southern plateaus of Utah, known as the Grand Staircase - home to Kodachrome Basin State Park, Bryce Canyon, are a classical example of this environment as we know it today. However, a record spanning the past 300 thousand years is preserved on the steps of the staircase indicating periods in the past where the climate …


Pleistocene Deposits Of Lower Wahweap Creek And Its Tributaries, Southern Utah, Noah Slade Dec 2022

Pleistocene Deposits Of Lower Wahweap Creek And Its Tributaries, Southern Utah, Noah Slade

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The famous landscapes of the Colorado Plateau have been created over millions of years, primarily by erosive forces of wind and water. Interruptions in the long-term erosion of the landscape occur when streams gain more sediment than they can transport, which causes deposition along channels and floodplains. The resulting sequences of terrace deposits are used by geologists to study when and how river systems have evolved.

Mammoth bones were recently discovered in stream deposits along Wahweap Creek, a tributary of the Colorado River in southern Utah. Previous work indicates that the deposits pre-date the last ice age, making it one …


Bedrock Geology Map Of The Naomi Peak 7.5' Quadangle, Cache County, Utah And Novel Age Constraints On Its Cambrian Strata, Hannah R. Cothren Dec 2022

Bedrock Geology Map Of The Naomi Peak 7.5' Quadangle, Cache County, Utah And Novel Age Constraints On Its Cambrian Strata, Hannah R. Cothren

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Geologists use various “rock-clocks” in order to interpret the timing and tempo of events in Earth’s history. These include global geochemical events in the oceans (chemostratigraphy), the evolution of certain fossil species (trilobite biostratigraphy), and the radiogenic decay of uranium to lead in certain mineral such as zircon (U-Pb geochronology). Integrating these methods in the stratigraphic record in one location can provide a well-constrained timeline for a select part of the Geologic, or Deep Time, record. This technique is especially important in the Cambrian Period (538.8 to 486.9 million years; Ma), which sets the stage for life today with the …


Regolith And Host Rock Influences On Co2 Leakage: Active Source Seismic Profiling Across The Little Grand Wash Fault, Utah, Lee M. Liberty, Jonathan Yelton, Elin Skurtveit, Alvar Braathen, Ivar Midtkandal, James P. Evans Aug 2022

Regolith And Host Rock Influences On Co2 Leakage: Active Source Seismic Profiling Across The Little Grand Wash Fault, Utah, Lee M. Liberty, Jonathan Yelton, Elin Skurtveit, Alvar Braathen, Ivar Midtkandal, James P. Evans

Geosciences Faculty Publications

Understanding carbon dioxide (CO2) reservoir to surface migration is crucial to successful carbon capture and sequestration approaches; especially fault/reservoir interactions under injection pressure. Through seismic imaging, we explore regolith and shallow stratigraphy across the Little Grand Wash fault. The presence of natural CO2 seeps, travertine and tufa deposits confirm modern and ancient fault-controlled CO2 leakage. We consider this an analogue for a long-failed sequestration site. We estimate bulk porosity and fracture density for host rock, regolith, and fault zone from petrophysical relationships. When combined with existing geochemical and geological data, we characterize a 60 m wide …


Natural And Experimental Slow Slip Observed Along Shallow Hematite Faults, Alexandra A. Dimonte Aug 2022

Natural And Experimental Slow Slip Observed Along Shallow Hematite Faults, Alexandra A. Dimonte

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fault slip relieves stress in the shallow crust by slipping suddenly during earthquakes, but some faults also slip slowly in between earthquakes. Exhumed faults, brought up to the Earth’s surface from depth, preserve a record of fault processes and slip rates informed by fault rock structures, textures, and chemistry. Hematite, a common iron oxide mineral that precipitates on fault surfaces, exhibits crystal textures that potentially indicate past slip rate. Hematite can be dated using the radioisotopic system of (U-Th)/He thermochronometry, which constrains the time when He is trapped within a crystal, a process that is a function of temperature. Exhumed …


Evaluation Of The Geothermal Potential Of The Camas Prairie, South-Central Idaho, Connor J. Smith Aug 2022

Evaluation Of The Geothermal Potential Of The Camas Prairie, South-Central Idaho, Connor J. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The area studied in this thesis was assessed based on the analysis of a water sample collected from the exploratory well USU Camas-1. The water sample was characterized and compared to other water samples collected and analyzed during a previous phase of this project according to its water chemistry.

Lithologic, geophysical, and temperature logs were also used to assess the study area. The depth sensitive data was analyzed to determine the characteristics of the formation as they relate to the favorable parameters of a geothermal resource, those being permeability of the subsurface, heat, and the presence of a clay seal. …


Shallow Composition And Structure Of The San Gabriel Fault, California In Drill Core And Geophysical Logs: Implications For Fault Slip And Energetics, Kaitlyn A. Crouch May 2022

Shallow Composition And Structure Of The San Gabriel Fault, California In Drill Core And Geophysical Logs: Implications For Fault Slip And Energetics, Kaitlyn A. Crouch

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Earthquakes are the sudden and intensive release of energy due to slip along faults. This energy may be felt on the Earth’s surface and may cause displacement of the Earth’s crust (seismic slip). As an earthquake ruptures, rocks in and around the fault are damaged and altered. When a fault displaces without earthquakes, it is referred to as aseismic creep. Faults may experience both seismic slip and aseismic creep throughout their cycles. In order to better model earthquake hazards and understand the cause of seismic slip versus aseismic creep in the shallow crust, we need to characterize the properties of …


Isotopic Analysis Of Hydrous Phenocrysts In Lava Flows Of The Peruvian Altiplano Plateau: Testing For A Subduction Signature, Alyssa Schiwal Apr 2022

Isotopic Analysis Of Hydrous Phenocrysts In Lava Flows Of The Peruvian Altiplano Plateau: Testing For A Subduction Signature, Alyssa Schiwal

Student Research Symposium

The process of flat-slab subduction introduces fluids directly into the overlaying lithosphere, leaving behind a unique stable isotope and trace element signature to the surrounding crust/mantle. Fluid alteration of the deep lithosphere can help explain geologic processes that are observed at the surface, such as patterns of crustal deformation (mountain building) and volcanism. The young high-K mafic volcanic rocks found in the Altiplano region of Southern Peru are derived from the melting of an altered mantle source. By analyzing the hydrogen stable isotopes as well as the trace elements of these volcanic rocks we can locate the water source associated …


Detecting Climate Change In Trilobite Time, Michelle Norman Apr 2022

Detecting Climate Change In Trilobite Time, Michelle Norman

Student Research Symposium

Trilobites are a signature marine fossil of the Cambrian explosion, which took place about 500 Ma (million years ago). By studying these fossiliferous rocks (limestone), we can get an understanding of ecological and environmental change. In fact, we can detect the ancient carbon cycle by measuring stable carbon isotopes in these limestone samples. By studying the carbon environment the trilobites lived in and which trilobite species evolve or go extinct, we can learn more about ancient climate events and constrain them to a certain period of time based off the age of radioactive zircons we find in sandy material around …


The Mechanics Of Initiation And Development Of Thrust Faults And Thrust Ramps, Sarah S. Wigginton, Elizabeth S. Petrie, James P. Evans Mar 2022

The Mechanics Of Initiation And Development Of Thrust Faults And Thrust Ramps, Sarah S. Wigginton, Elizabeth S. Petrie, James P. Evans

Geosciences Faculty Publications

This study integrates the results of numerical modeling analyses based on outcrop studies and structural kinematic restorations to evaluate the mechanics of thrust fault initiation and development in mechanically layered sedimentary rocks. A field-based reconstruction of a mesoscopic thrust fault at Ketobe Knob in central Utah provides evidence of thrust ramp nucleation in competent units, and fault propagation upward and downward into weaker units at both fault tips. We investigate the effects of mechanical stratigraphy on stress heterogeneity, rupture direction, fold formation, and fault geometry motivated by the geometry of the Ketobe Knob thrust fault in central Utah; the finite …


The Economic Contribution Of Utah's Energy And Mining Industries, Tanner J. Mccarty, Zuyi Wang, Man-Keun Kim, James Evans Jan 2022

The Economic Contribution Of Utah's Energy And Mining Industries, Tanner J. Mccarty, Zuyi Wang, Man-Keun Kim, James Evans

Geosciences Faculty Publications

Utah’s abundant energy and mineral resources are used to heat homes, drive industry, and keep the lights on. Effectively managing these energy and mineral resources and their associated supply chains requires knowledge of their economic value and how they currently contribute to Utah’s economy. This report calculates the total economic contribution of Utah’s energy and mining industries for 2019 and 2020. Each industry makes substantial contributions to Utah’s gross domestic product, employment, and tax base. Table 1 displays each industry’s economic contribution to Utah’s economy.

Collectively, these industries contributed over 10% to Utah's total Gross Domestic Product (GDP), supported over …


Lithological And Geochemical Characterization Of Ramp Sediments And A Depositional Model Of The Ordovicain Garden City Formation, Northeastern Utah, Kenneth W. Kehoe Dec 2021

Lithological And Geochemical Characterization Of Ramp Sediments And A Depositional Model Of The Ordovicain Garden City Formation, Northeastern Utah, Kenneth W. Kehoe

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Ordovician Garden City Formation is a mostly marine limestone rock formation deposited in what is known today as the Northern Utah Basin in North America ~485.5 million years ago. Previous research on the Pogonip Group, a time equivalent rock formation located in the Ibex Basin south of the Northern Utah Basin, has identified nine cycles of sea-level fall and rise. However, these nine sea-level cycles have proven difficult to identify within the Garden City Formation due to the limited contrast between rock types within the rock formation. Previous research on the Garden City has approximated these sea-level cycles through …


Redefining The Age Of The Lower Colorado River, Southwestern United States: Forum Reply, R. S. Crow, J. Schwing, K. E. Karlstrom, M. Heizler, P. A. Pearthree, P. K. House, S. Dulin, Susanne U. Jänecke, M. Stelten, L. J. Crossey Sep 2021

Redefining The Age Of The Lower Colorado River, Southwestern United States: Forum Reply, R. S. Crow, J. Schwing, K. E. Karlstrom, M. Heizler, P. A. Pearthree, P. K. House, S. Dulin, Susanne U. Jänecke, M. Stelten, L. J. Crossey

Geosciences Faculty Publications

No abstract provided.


Collaborative Research: Deciphering The Role Of Extreme Rainstorms And Hydroclimatic Regime On Arid Escarpment Retreat And Sub-Cliff Slope Evolution, Joel Pederson Aug 2021

Collaborative Research: Deciphering The Role Of Extreme Rainstorms And Hydroclimatic Regime On Arid Escarpment Retreat And Sub-Cliff Slope Evolution, Joel Pederson

Funded Research Records

No abstract provided.


Exploring Questions Of Tectonic Geomorphology In The Bear River Range, Utah Using Terrain Analysis And Reconstruction, Edward M. Grasinger Aug 2021

Exploring Questions Of Tectonic Geomorphology In The Bear River Range, Utah Using Terrain Analysis And Reconstruction, Edward M. Grasinger

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Despite a long tradition of geologic studies in the region surrounding Utah State University, there remain unexplored questions and unutilized approaches for understanding the landscape evolution of the Bear River Range. A large-scale reconstruction of the East Cache fault system can be useful in estimating the total displacement of the fault, its geologic longevity, and total energy involved. Likewise, an analysis of reach-scale features of the Logan River can explore how tectonics and bedrock type affect the patterns and history of the river. Geographic Information Systems (GIS) software is useful in reconstructing, visualizing, and measuring such geomorphological features and changes …


Constraining Deformation Mechanisms Of Fault Damage Zones: A Case Study Of The Shallow San Andreas Fault At Elizabeth Lake, Southern California., Caroline Studnicky Aug 2021

Constraining Deformation Mechanisms Of Fault Damage Zones: A Case Study Of The Shallow San Andreas Fault At Elizabeth Lake, Southern California., Caroline Studnicky

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Earthquakes nucleate at depth and rupture along the fault plane up to the Earth’s surface releasing seismic energy as the fault propagates. This energy creates the shaking we feel on the surface. Some faults do not rupture and create shaking but deform slowly and smoothly accommodating fault slip over extended time periods. This process is referred to as aseismic slip or creep. Whether a fault ruptures or creeps depends on the properties of the rocks through which the fault plane extends. In order to model seismic hazards correctly, we need to characterize the composition, deformation structures, and alteration materials of …


Multi-Proxy Approach To Robustly Capture Earthquake Temperature Rise At The Punchbowl Fault, California, Emma M. Armstrong Aug 2021

Multi-Proxy Approach To Robustly Capture Earthquake Temperature Rise At The Punchbowl Fault, California, Emma M. Armstrong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Earthquakes produce heat along a fault surface from friction created as two blocks of rock move past each other. The amount of heat generated depends on a variety of factors, including rock type, stresses, and thickness of the fault zone. Identifying evidence for and quantifying this earthquake (coseismic) temperature rise are essential for identifying past earthquakes in the rock record. Indirect methods, such as textures and geochemical signatures that change with temperature, can serve as paleothermometers. Here we compare two paleothermometers, biomarkers and thermochronometry, from two transects across the Punchbowl fault (PF), California. The PF is an ancient fault strand …


Geologic Characterization Of The Nonconformity Interface Using Outcrop And Drillcore Analogs: Implications For Injection-Induced Seismicity, Kayla Smith Aug 2021

Geologic Characterization Of The Nonconformity Interface Using Outcrop And Drillcore Analogs: Implications For Injection-Induced Seismicity, Kayla Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Starting around 2009, a greater number of earthquakes than anticipated have occurred in the midcontinent region of the United States. These earthquakes have been linked to increased rates and volumes of wastewater injection at several km’s depth into the Earth’s crust near a contact between crystalline metamorphic or igneous rock and overlying sedimentary rock, known as a nonconformity. While much is known about why these new earthquakes occur, comparatively little is known about the physical and chemical rock properties because the nonconformity contact is primarily buried under km’s of sedimentary rock in the midcontinent region. These rock properties are important …


Collaborative Research: A Fossil Ecosystem Under The Ice: Deciphering The Glacial And Vegetation History Of Nothwest Greenland Using Long Lost Camp Century Basal Sediment, Tammy M. Rittenour Jul 2021

Collaborative Research: A Fossil Ecosystem Under The Ice: Deciphering The Glacial And Vegetation History Of Nothwest Greenland Using Long Lost Camp Century Basal Sediment, Tammy M. Rittenour

Funded Research Records

No abstract provided.


Digital Appendix Of Masters Thesis "Constraining Deformation Mechanisms Of Damage Zones: A Case Study Of The Shallow San Andreas Fault At Elizabeth Lake, Southern California, James P. Evans, Caroline Studnicky May 2021

Digital Appendix Of Masters Thesis "Constraining Deformation Mechanisms Of Damage Zones: A Case Study Of The Shallow San Andreas Fault At Elizabeth Lake, Southern California, James P. Evans, Caroline Studnicky

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We performed macroscopic, optical petrographic, scanning electron microscopy, and geochemical analyses on rock core acquired across the San Andreas Fault at Elizabeth Lake, California, in order to understand the distribution and accommodation of fault-related slip and energy within the shallow damage zone of this continental scale strike-slip fault. We characterized the deformation structures, alteration textures, and elemental variabilities to constrain the properties of the uppermost ~2 km fault-related damage zone at this site. We identified evidence for coseismic slip in the form of pulverized rocks, injection veins, clay-clast aggregates, and pseudotachylyte, and aseismic slip through calcite twins, dilatant vein fills, …


Taphonomy Of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated With Teeth From Allosaurus Sp. And Ceratosaurus Sp., And Body Size Extrapolation From The Associated Theropod Teeth., Greg C. Agyan May 2021

Taphonomy Of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated With Teeth From Allosaurus Sp. And Ceratosaurus Sp., And Body Size Extrapolation From The Associated Theropod Teeth., Greg C. Agyan

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

An Apatosaurus sp. locality from Dinosaur National Monument designated DNM-15 was excavated in 1985, and associated with two Allosaurus teeth and one Ceratosaurus tooth that were near one of the caudal vertebrae. The Ceratosaurus tooth was buried between an overlying rib and that same caudal vertebra. The caudal vertebrae of the DNM-15 Apatosaurus were intact and articulated, but the anterior skeleton was mostly absent, with a row of articulated sacral vertebrae in close association with a femur. Two other Allosaurus teeth were reported near the preserved ilium of the Apatosaurus, but they could not be located in the collections. …