Geology Commons^™

The Biggest Snowball Fight In Earth History: Stratigraphy, Facies Analysis, And Geochronology Of The Pocatello Formation, Matthew W. Ellison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Snowball Earth Hypothesis details a time in Earth’s history (the Cryogenian period) where the entire planet was encapsulated by kilometer thick ice sheets for two, multi-million-year glaciations. The first, known as the Sturtian, lasted from 717 – 660 million years ago while the second, known as the Marinoan, lasted form approximately 650 – 635 million years ago. Snowball Earth was caused by a few processes that sort of built upon each other: Rodinia began splitting apart ~740 million years ago which allowed for increased rates of silicate weathering. High rates of silicate weathering resulted in CO₂ drawdown which …

Spatial And Temporal Patterns Of River Incision And Terrace Deposition In Response To Climate And Tectonics In Southern Taiwan, Dominique M. Shore

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Geologists often look at the Earth’s surface to understand the underlying processes that cause mountain formation. As tectonic forces drive uplift of Earth’s surface, processes of erosion transport sediment to lower elevations. Climate can play a large role in landscape formation as well as increased precipitation, accelerating rates of erosion. Rivers leave markers of landscape evolution through terrace landforms, former river floodplains that are left behind when rivers incise into a valley. To better understand landscape response to uplift, this research investigated the initial linkages between uplift, hillslope erosion (mass wasting) and river incision. At some point, it is thought …

Collaborative Research: Identifying Shallow Slow Slip Using Hematite Tectures And (U-Th)/He Thermochonometry Of Exhumed And Experimental Faults, Alexis Ault

Funded Research Records

No abstract provided.

Redefining The Age Of The Lower Colorado River, Southwestern United States, 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

Sanidine dating and magnetostratigraphy constrain the timing of integration of the lower Colorado River (southwestern United States and northern Mexico) with the evolving Gulf of California. The Colorado River arrived at Cottonwood valley (Nevada and Arizona) after 5.24 Ma (during or after the Thvera subchron). The river reached the proto–Gulf of California once between 4.80 and 4.63 Ma (during the C3n.2r subchron), not at 5.3 Ma and 5.0 Ma as previously proposed. Duplication of section across newly identified strands of the Earthquake Valley fault zone (California) probably explains the discrepancy. The data also imply the start of focused plate motion …

The Age And Origin Of Precambrian Orthogneiss Of The Grouse Creek Block, Northern Utah And Southern Idaho, Skadi Kobe

Fall Student Research Symposium 2020

New geochronologic and isotopic analyses from the Grouse Creek block (GC) provide insight into the assembly of western Laurentia during the late Archean to Paleoproterozoic and establish the influence of the GC in the evolution of Yellowstone-Snake River Plain hotspot magmatism in the central Snake River Plain. The GC is primarily exposed in the Albion-Raft River-Grouse Creek metamorphic core complex of northern Utah and southern Idaho and includes a complex assemblage of orthogneiss, schist, amphibolite, and metasediments intruded by Oligocene plutons and overlain by Cenozoic sedimentary units. Many investigations of the GC have focused on the structural evolution of the …

Hazard Analysis Of A Segment Of Highway Sr-12 Through Bryce Canyon National Park, Southern Utah, Tomsen Reed

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

Over 2.6 million people travel along highway SR-12, a National Scenic Byway, through Bryce Canyon in southern Utah each year. This highway is a major thoroughfare for tourists traveling to Bryce Canyon National Park, Grand Staircase-Escalante National Monument, and other scenic attractions. SR-12 is susceptible to rockfall and landslide hazards where it descends from the Paunsaugunt Plateau into Tropic Canyon, and these hazards have potential consequences of economic loss due to travel delays for tourists and commodities, and possible loss of life. Rockfall could have devastating effects at this location because of the traffic volume, sharp turns, low visibility, and …

Pre-Eruptive Evolution Of Izu-Bonin Boninite Melts: Mixing, Cooling, And Crystallization, Jesse L. Scholpp

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Subduction is the geologic process in which one tectonic plate moves beneath another as it sinks into the Earth’s mantle. Subduction initiation in the Izu-Bonin Marianas system is the result of a gravitational failure during which one tectonic plate (the Pacific plate) spontaneously sinks beneath another (the Philippne Sea plate). Fluids released by the sinking plate that caused the overlying mantle to melt by reducing its meltimg temperature, forming the Izu-Bonin Mariana island arc system.

The resulting melts initially have the chemical compositions that are rich in silica and magnesia, and highly depleted in other elements, refered to a boninite …

Lidar Reveals >150 Km Of New Holocene Ruptures And Faults In Northeast Basin-And-Range Province, N Utah And Se Idaho, Susanne U. Jänecke, Nathaniel R. Ellis, Robert Q. Oaks Jr., Carly M. Lee, James P. Evans

Geosciences Faculty Publications

Cache Valley is a N-trending graben in N-central Utah and SE Idaho. The East Cache fault zone (ECFZ) appears to be the master fault due to the high mountain in its footwall, its inversion of the Providence thrust fault, and the deep sedimentary basin in its hanging wall. However, trenching in 1990s showed more Holocene ruptures within the West Cache fault zone (WCFZ, 4) than ECFZ (1). We use LIDAR data to document post-Bonneville paleo-earthquakes along known and newly documented normal faults of the WCFZ. New faults with scarps occur throughout the ~105 km long and 5-10 km wide WCFZ. …

Collaborative Research: Constraining The Tempo And Dynamics Of Cambrian Earth Systems In Western Laurentia, Carol M. Dehler

Funded Research Records

No abstract provided.

Geomorphic History Of The Grand Staircase Region Of The Colorado Plateau: Understanding Arroyo Cut-Fill Dynamics, Erosion Rates, And Wildfire, Kerry E. Riley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Most streams in the southwestern United States do not flow all year, and given their delicate balance of sediment and water flow, they are sensitive to climate change. At the turn of the 20th century, many streams in the Southwest rapidly incised into their floodplains, forming arroyos with a channel entrenched into near-vertical channel banks mostly composed of sand and mud. This dissertation investigates past changes in watersheds draining the Grand Staircase region in southern Utah with the goal of understanding how changes in climate and sediment influence these types of streams. Results show sediment supply is highly variable across …

Connections Between Hydrothermal System Geochemistry And Microbiology: Traversing Tectonic Boundaries In The South-Central Peruvian Andes, Heather Upin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Geochemistry and microbiology are inherently tied in the natural world. The study of geomicrobiology has historically taken place in extreme systems, like hot springs of Yellowstone National Park and deep-sea hydrothermal vents, because the organisms that exist there have deep lineages on the tree of life and provide insight into early life on Earth. These microbes use chemical energy from nutrients available in their environment rather than relying on photosynthesis, energy obtained from the sun, to support their metabolism. The goal of this study is to improve our understanding of geological controls (for example the tectonic setting) on hot spring …

Fire Suppression Impacts On Fuels And Fire Intensity In The Western U.S.: Insights From Archaeological Luminescence Dating In Northern New Mexico, Christopher I. Roos, Tammy M. Rittenour, Thomas W. Swetnam, Rachel A. Loehman, Kacy L. Hollenback, Matthew J. Liebmann, Dana Drake Rosenstein

Geosciences Faculty Publications

Here, we show that the last century of fire suppression in the western U.S. has resulted in fire intensities that are unique over more than 900 years of record in ponderosa pine forests (Pinus ponderosa). Specifically, we use the heat-sensitive luminescence signal of archaeological ceramics and tree-ring fire histories to show that a recent fire during mild weather conditions was more intense than anything experienced in centuries of frequent wildfires. We support this with a particularly robust set of optically stimulated luminescence measurements on pottery from an archaeological site in northern New Mexico. The heating effects of an October 2012 …

Structural Controls On Crustal Fluid Circulation And Hot Spring Geochemistry Above A Flat‐Slab Subduction Zone, Peru, Brandt E. Scott, Dennis L. Newell, M. J. Jessup, T. A. Grambling, C. A. Shaw

Geosciences Faculty Publications

Hot spring geochemistry from the Cordillera Blanca and Cordillera Huayhuash, Peru, reveal the influence of crustal‐scale structures on geothermal fluid circulation in an amagmatic region located above a flat‐slab subduction zone. To test the influence of contrasting modes of faulting in these regions, springs were targeted along the Cordillera Blanca detachment fault, within its hanging wall, in the footwall of the detachment, and in the Cordillera Huayhuash. Hot springs along the Cordillera Blanca detachment fault zone are associated with recent extension and normal faulting, and those in its footwall and the Cordillera Huayhuash are located in the Marañon fold and …

Links Between Eruptive Styles, Magmatic Evolution, And Morphology Of Shield Volcanoes: Snake River Plain, Idaho, Katelyn J. Barton, Michelle Hurst

Utah Space Grant Consortium

Despite their similar ages and geographic locations, two low-shield volcanoes on the eastern Snake River Plain, Idaho, Kimama Butte (87 ka) and Rocky Butte (95 ka), have strikingly different profiles. In this study, these two volcanoes are examined to determine the connections between chemical composition, intensive parameters, eruption style, and topographic features of basaltic shield volcanoes. Because lava temperature, magma viscosity, and chemical composition overlap at the two volcanoes, they are probably not important controls on the differences in morphology. The main difference at the two shields, aside from general vent morphology, is the presence of late-stage, phenocryst-rich, high viscosity …

Nanotextural And Nanochemical Constraints On The Role Of Heat In The Development Of Crystalline-Hosted, Silica-Rich Fault Mirrors In The Wasatch Fault Damage Zone, Utah, Usa, Leah M. Houser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Earthquakes occur on faults, or rock that has experienced displacement at depth. Experimental work on a range of rock types reveals that >90% of earthquake energy on fault surfaces is given off as heat. Heat weakens rock and promotes earthquake rupture propagation. Thin (<0.5mm), high-gloss, "polished", light-reflective exposed fault surfaces are called fault mirrors (FMs). Fault mirrors may record rapid thermal, textural, and chemical changes that occur during an earthquake event.

The Wasatch Mountains are a N-S trending mountain range in Northern Utah that are the backdrop for Salt Lake City, Provo, Ogden, and Brigham City. This mountain range is currently built by the active Wasatch fault, and includes the exposed Wasatch fault damage zone. Many segments of the Wasatch fault are overdue for a potentially catastrophic …

Hematite (U-Th)/He Thermochronometry Detects Asperity Flash Heating During Laboratory Earthquakes, Melissa S. Chapot, Alexis K. Ault, Greg Hirth, Robert G. Mcdermott

Geosciences Faculty Publications

Evidence for coseismic temperature rise that induces dynamic weakening is challenging to directly observe and quantify in natural and experimental fault rocks. Hematite (U-Th)/He (hematite He) thermochronometry may serve as a fault-slip thermometer, sensitive to transient high temperatures associated with earthquakes. We test this hypothesis with hematite deformation experiments at seismic slip rates, using a rotary-shear geometry with an annular ring of silicon carbide (SiC) sliding against a specular hematite slab. Hematite is characterized before and after sliding via textural and hematite He analyses to quantify He loss over variable experimental conditions. Experiments yield slip surfaces localized in an ∼5–30-µm-thick …

Collaborative Research: Quantifying Crustal Hydration Effects In The Colorado Plateau From Xenoliths, Dennis Newell

Funded Research Records

No abstract provided.

Crustal Composition And Moho Variations Of The Central And Eastern United States: Improving Resolutionand Geologic Interpretation Of Earthscope Usarray Seismic Images Using Gravity, H. L. Zhang, D. Ravat, Anthony R. Lowry

Geosciences Faculty Publications

EarthScope's USArray Transportable Array has shortcomings for the purpose of interpreting geologic features of wavelengths less than the Transportable Array station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce nonuniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously derived density variations of sedimentary basins, crustal V_p/V_s variation, Moho variation, and upper mantle density variation derived from body wave imaging informed by surface wave tomography to estimate V_p/V_s. Although average densities and density contrasts for …

Mariana Serpentinite Mud Volcanism Exhumes Subducted Seamount Materials: Implications For The Origin Of Life., Patricia Fryer, C. Geoffrey Wheat, Trevor Williams, Christopher Kelley, Kevin Johnson, Jeffrey Ryan, Walter Kurz, John W. Shervais, Elmar Albers, Barbara Bekins, Baptiste Debret, Jianghong Deng, Yanhui Dong, Philip Eickenbusch, Emanuelle Frery, Yuji Ichiyama, Richard Kevorkian, Et Al.

Geosciences Faculty Publications

The subduction of seamounts and ridge features at convergent plate boundaries plays an important role in the deformation of the overriding plate and influences geochemical cycling and associated biological processes. Active serpentinization of forearc mantle and serpentinite mud volcanism on the Mariana forearc (between the trench and active volcanic arc) provides windows on subduction processes.  Here, we present (1) the first observation of an extensive exposure of an undeformed Cretaceous seamount currently being subducted at the Mariana Trench inner slope; (2) vertical deformation of the forearc region related to subduction of Pacific Plate seamounts and thickened crust; (3) recovered Ocean …

Evolution Of The Book Cliffs Dryland Escarpment In Central Utah - Establishing Rates And Testing Models Of Escarpment Retreat, Nicholas R. Mccarroll

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since the earliest explorations of the Colorado Plateau, geologists have suspected that cliffs are retreating back laterally. Clarence Dutton envisioned “the beds thus dissolving edge wise until after the lapse of millions of centuries their terminal cliffs stand a hundred miles or more back from their original position” when he wrote about the landscape in 1882. While many geologic studies have determined how fast rivers cut down through the Plateau, only a few studies have calculated how quickly cliffs retreat laterally, and geologists have been arguing since the 1940’s what exactly drives cliffs to retreat in the first place. We …

Sampling Methods For Luminescence Dating Of Subsurface Deposits From Cores, Michelle Nelson, Tammy M. Rittenour, Harriet Cornachione

Geosciences Faculty Publications

Study of subsurface deposits often requires coring or drilling to obtain samples for sedimentologic and geochemical analysis. Geochronology is a critical piece of information for stratigraphic correlation and rate calculations. Increasingly, luminescence dating is applied to sediment cores to obtain depositional ages. This paper provides examples and discussion of guidelines for sampling sediment core for luminescence dating. Preferred protocols are dependent on the extraction method, sedimentology, core integrity, and storage conditions. The methods discussed include subsampling of sediment in opaque core-liners, cores without liners, previously open (split) cores, bucket auger samples, and cuttings, under red lighting conditions. Two important factors …

Postmagmatic Tectonic Evolution Of The Outer Izu‐Bonin Forearc Revealed By Sediment Basin Structure And Vein Microstructure Analysis: Implications For A 15 Ma Hiatus Between Pacific Plate Subduction Initiation And Forearc Extension, Walter Kurz, Peter Micheuz, Gail L. Christeson, M. Reagan, John W. Shervais, Steffen Kutterolf, A. Robertson, Kurt Krenn, K. Michibayashi, D. Quandt

Geosciences Faculty Publications

International Ocean Discovery Program Expedition 352 recovered sedimentary‐volcaniclastic successions and extensional structures (faults and extensional veins) that allow the reconstruction of the Izu‐Bonin forearc tectonic evolution using a combination of shipboard core data, seismic reflection images, and calcite vein microstructure analysis. The oldest recorded biostratigraphic ages within fault‐bounded sedimentary basins (Late Eocene to Early Oligocene) imply a ~15 Ma hiatus between the formation of the igneous basement (52 to 50 Ma) and the onset of sedimentation. At the upslope sites (U1439 and U1442) extension led to the formation of asymmetric basins reflecting regional stretch of ~16–19% at strain rates of …

Nanoscale Evidence For Temperature-Induced Transient Rheology And Postseismic Fault Healing, Alexis K. Ault, Jordan L. Jensen, Robert G. Mcdermott, F.-A. Shen, B. R. Van Devener

Geosciences Faculty Publications

Friction-generated heat and the subsequent thermal evolution control fault material properties and thus strength during the earthquake cycle. We document evidence for transient, nanoscale fault rheology on a high-gloss, light-reflective hematite fault mirror (FM). The FM cuts specularite with minor quartz from the Pleistocene El Laco Fe-ore deposit, northern Chile. Scanning and transmission electron microscopy data reveal that the FM volume comprises a2+ suboxides. Sub–5-nm-thick silica films encase hematite grains and connect to amorphous interstitial silica. Observations imply that coseismic shear heating (temperature >1000 °C) generated transiently amorphous, intermixed but immiscible, and rheologically weak Fe-oxide and silica. Hematite regrowth in …

Evaluation Of The Geothermal Potential Of The Western Snake River Plain Based On A Deep Corehole On The Mountain Home Afb Near Mountain Home, Idaho, Thomas E. Lachmar, Thomas G. Freeman, James Andrew Kessler, Joseph F. Batir, James P. Evans, Dennis L. Nielson, John W. Shervais, Xiwei Chen, Douglas R. Schmitt, David D. Blackwell

Geosciences Faculty Publications

A geothermal exploration corehole was drilled to a total depth of 1821.5 m on the Mountain Home Air Force Base near Mountain Home, Idaho. The corehole was used to collect an unusually large amount of data, including uniaxial compressive stress (UCS) experiments on core samples, to evaluate the geothermal potential of the western Snake River Plain. In addition, unlike many exploration holes in this region, a fluid entry was encountered at 1745.3 m and flowed artesian to the surface. A maximum temperature of 149.4 °C was calculated for the entry. A temperature log run on the corehole from 3 to …

Collaborative Research: Development And Application Of A Framework For Integrated Geodynamic Earth Models, Anthony Lowry

Funded Research Records

No abstract provided.

Innovations In (U–Th)/He, Fission Track, And Trapped Charge Thermochronometry With Applications To Earthquakes, Weathering, Surface‐Mantle Connections, And The Growth And Decay Of Mountains, Alexis K. Ault, Cécile Gautheron, Georgina E. King

Geosciences Faculty Publications

A transformative advance in Earth science is the development of low‐temperature thermochronometry to date Earth surface processes or quantify the thermal evolution of rocks through time. Grand challenges and new directions in low‐temperature thermochronometry involve pushing the boundaries of these techniques to decipher thermal histories operative over seconds to hundreds of millions of years, in recent or deep geologic time and from the perspective of atoms to mountain belts. Here we highlight innovation in bedrock and detrital fission track, (U–Th)/He, and trapped charge thermochronometry, as well as thermal history modeling that enable fresh perspectives on Earth science problems. These developments …

Thermotectonic History Of The Kluane Ranges And Evolution Of The Eastern Denali Fault Zone In Southwestern Yukon, Canada, Robert G. Mcdermott, Alexis K. Ault, Jonathan Saul Caine, Stuart N. Thomson

Geosciences Faculty Publications

Exhumation and landscape evolution along strike‐slip fault systems reflect tectonic processes that accommodate and partition deformation in orogenic settings. We present 17 new apatite (U‐Th)/He (He), zircon He, apatite fission‐track (FT), and zircon FT dates from the eastern Denali fault zone (EDFZ) that bounds the Kluane Ranges in Yukon, Canada. The dates elucidate patterns of deformation along the EDFZ. Mean apatite He, apatite FT, zircon He, and zircon FT sample dates range within ~26–4, ~110–12, ~94–28, and ~137–83 Ma, respectively. A new zircon U‐Pb date of 113.9 ± 1.7 Ma (2σ) complements existing geochronology and aids in interpretation …

Collaborative Research: Tespresso, Tectonic Encoding, Shredding, And Propagation Of Environmental Signals As Surficial Observables, Tammy M. Rittenour

Funded Research Records

No abstract provided.

Deformation Conditions During Syn-Convergent Extension Along The Cordillera Blanca Shear Zone, Peru, Cameron A. Hughes, Micah J. Jessup, Colin A. Shaw, Dennis L. Newell

Geosciences Faculty Publications

Strain localization across the brittle-ductile transition is a fundamental process in accommodating tectonic movement in the mid-crust. The tectonically active Cordillera Blanca shear zone (CBSZ), a ∼200-km-long normal-sense shear zone situated within the footwall of a discrete syn-convergent extensional fault in the Peruvian Andes, is an excellent field laboratory to explore this transition. Field and microscopic observations indicate consistent top-down-to-the-southwest sense of shear and a sequence of tectonites ranging from undeformed granodiorite through mylonite and ultimately fault breccia along the detachment.

Using microstructural analysis, two-feldspar and Ti-in-quartz (TitaniQ) thermometry, recrystallized quartz paleopiezometry, and analysis of quartz crystallographic preferred orientations, we …

Assessing Paleoenvironmental And Geomorphic Variability In Relationship To Paleoindian Site Burial; Centennial Valley, Montana, Hillary A. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wave action along the shores of Lima Reservoir in Centennial Valley, Montana is actively eroding the southern margins of three neighboring Paleoindian sites. Despite ostensible similarity among the sites, major site formation differences are apparent in exposed sediments. Shoreline cutbank exposures one-to-five meters high connect the sites and reveal a complicated geomorphic history. Although each site contains artifact evidence of terminal Pleistocene-early Holocene occupations, Paleoindian components at these three localities occur in very different contexts: one is buried, while the other two are apparent surface scatters. This raise the question of why sites of the same age are in both …