Physical Sciences and Mathematics Commons^™

Magmatic Response To Subduction Initiation: Part 1. Fore-Arc Basalts Of The Izu-Bonin Arc From Iodp Expedition 352, John W. Shervais, Mark Reagan, Emily A. Haugen, Renat R. Almeev, Julian A. Pearce, Julie Prytulak, Jeffrey G. Ryan, Scott A. Whattam, Marguerite Godard, Timothy Chapman, Hongyan Li, Walter Kurz, Wendy R. Nelson, Daniel Heaton, Maria Kirchenbaur, Kenji Shimizu, Tetsuya Sakuyama, Yibing Li, Scott K. Vetter

Geosciences Faculty Publications

The Izu-Bonin-Mariana (IBM) fore arc preserves igneous rock assemblages that formed during subduction initiation circa 52 Ma. International Ocean Discovery Program (IODP) Expedition 352 cored four sites in the fore arc near the Ogasawara Plateau in order to document the magmatic response to subduction initiation and the physical, petrologic, and chemical stratigraphy of a nascent subduction zone. Two of these sites (U1440 and U1441) are underlain by fore-arc basalt (FAB). FABs have mid-ocean ridge basalt (MORB)-like compositions, however, FAB are consistently lower in the high-field strength elements (TiO2, P2O5, Zr) and Ni compared to MORB, with Na2O at the low …

The Ages2 (Awards For Geochronology Student Research 2) Program: Supporting Community Geochronology Needs And Interdisciplinary Science, Rebecca M. Flowers, J. Ramón Arrowsmith, Vicki Mcconnell, James R. Metcalf, Tammy M. Rittenour, Blair Schoene

Geosciences Faculty Publications

Geochronology is essential in the geosciences. It is used to resolve the durations and rates of earth processes, as well as test causative relationships among events. Such data are increasingly required to conduct cutting-edge, transformative, earth-science research. The growing need for geochronology is accompanied by strong demand to enhance the ability of labs to meet this pressure and to increase community awareness of how these data are produced and interpreted. For example, a 2015 National Science Foundation (NSF) report on opportunities and challenges for U.S. geochronology research noted: "While there has never been a time when users have had greater …

New Ca-Id-Tims Detrital Zircon Constraints On Middle Neoproterozoic Sedimentary Successions, Southwestern United States, Abigail R. Bullard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Three related sedimentary successions located in Arizona, Utah, and California were deposited in basins on proto-North America during the early rifting of Rodinia (~780 Mya). Previous detrital zircon U-Pb maximum ages for the units are inexact, making it difficult to piece together what happened at this point in Earth history.

We report better maximum age constraints on these units obtained by subjecting detrital zircons to high-precision CA-ID-TIMS analysis, which provide more exact ²⁰⁶Pb/²³⁸U ages. These new data significantly improve the precision for the base of the ChUMP units, with an average age of 775.63 ± 0.27 Ma …

The Influence Of Mechanical Stratigraphy On Thrust-Ramp Nucleation And Propagation Of Thrust Faults, Sarah S. Wigginton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Our current understanding of thrust fault kinematics predicts that thrust faults nucleate on low angle, weak surfaces before they propagate upward and forms a higher angle ramp. While this classic kinematic and geometric model serves well in some settings, it does not fully consider the observations of footwall deformation beneath some thrust faults. We examine an alternative end-member model of thrust fault formation called “ramp-first” fault formation. This model hypothesizes that in mechanically layered rocks, thrust ramps nucleate in the structurally strong units, and that faults can propagate both upward and downward into weaker units forming folds at both fault …

The Role Of Fault-Zone Architectural Elements On Pore Pressure Propagation And Induced Seismicity, John P. Ortiz, Mark A. Person, Peter S. Mozley, James P. Evans, Susan L. Bilek

Geosciences Faculty Publications

We used hydrogeologic models to assess how fault‐zone properties promote or inhibit the downward propagation of fluid overpressures from a basal reservoir injection well (150 m from fault zone, Q = 5000 m3/day) into the underlying crystalline basement rocks. We varied the permeability of the fault‐zone architectural components and a crystalline basement weathered layer as part of a numerical sensitivity study. Realistic conduit‐barrier style fault zones effectively transmit elevated pore pressures associated with 4 years of continuous injection to depths of approximately 2.5 km within the crystalline basement while compartmentalizing fluid flow within the injection reservoir. The presence of a …

Alaskan Marine Transgressions Record Out-Of-Phase Arctic Ocean Glaciation During The Last Interglacial, Louise Farquharson, Daniel Mann, Tammy M. Rittenour, Pamela Groves, Guido Grosse, Benjamin Jones

Geosciences Faculty Publications

Ongoing climate change focuses attention on the Arctic cryosphere’s responses to past and future climate states. Although it is now recognized the Arctic Ocean Basin was covered by ice sheets and their associated floating ice shelves several times during the Late Pleistocene, the timing and extent of these polar ice sheets remain uncertain. Here we relate a relict barrier-island system on the Beaufort Sea coast of northern Alaska to the isostatic effects of a previously unrecognized ice shelf grounded on the adjacent continental shelf. A new suite of optically stimulated luminescence dates show that this barrier system formed during one …

Analysis Of The Parkway Drive Landslide, North Salt Lake, Ut, Brianna V. Hill

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

On August 5^th, 2014, a hillside failed behind a North Salt Lake City, UT neighborhood threatening several homes. Aerial Photography, Digital Elevation Models (DEM), geochemistry, rain gage and seismic data were used to test the influence of contributing factors in this landslide failure. Aerial photographs available from 1993 to present were examined for signs of tension cracks suggesting impending ground motion, as well as documentation of human modification along the hillslope. Repeat DEM analysis of elevation and slope of the hillside before and after the slide were examined to characterize the pre-failure hillslope and subsequent landslide. Geochemical analyses …

Durmid Ladder Structure And Its Implications For The Nucleation Sites Of The Next M >7.5 Earthquake On The San Andreas Fault Or Brawley Seismic Zone In Southern California, Susanne U. Jänecke, Daniel K. Markowski, James P. Evans, Patricia Persaud, Miles Kenney

Geosciences Faculty Publications

We integrated new geologic data with published geophysical data to document that the southernmost San Andreas fault zone, onshore of the Salton Sea, southern California, is a transpressional, 1–4-km-wide ladder-like structure. This newly identified Durmid ladder structure is a voluminous right-reverse fault zone that broadens across Durmid Hill around rotating domains of regularly spaced, left- and right- lateral cross faults. The active East Shoreline fault zone of the San Andreas fault forms the southwest margin of this fault zone, and it is generally parallel to the main strand of the San Andreas fault zone for >30 km, deforms Pliocene to …

Quaternary Incision, Salt Tectonism, And Landscape Evolution Of Moab-Spanish Valley, Utah, James P. Mauch

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To study the history of processes that shape the Earth’s surface, geologists look for markers in the landscape that they can date and use to measure change. Rivers leave such markers in their deposits and terrace landforms and in the overall shape of their elevation profile from head to toe. This thesis uses luminescence and cosmogenic methods to date the sediment in terraces to determine when the river deposited it. Field mapping and global positioning system (GPS) surveying are also used to measure the distance between terrace levels to quantify how much change has occurred. This study seeks to answer …

Understanding The Late Mesoproterozoic Earth System From The Oldest Strata In Grand Canyon: C-Isotope Stratigraphy And Facies Analysis Of The 1254 Ma Bass Formation, Grand Canyon Supergroup, Az., Usa, Erin C. Lathrop

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rocks provide insight into ancient times before complex animals existed. The oldest sedimentary rocks in Grand Canyon (the Bass Formation) allow us to glimpse into what things might have been like over a billion years ago. These rocks record the time known as the Mesoproterozoic Era (1.6 to 1.0 billion years ago), otherwise known as the ‘boring billion’. These rocks are thought to be the right age to indicate the end of an oddly stable world when continents were quiet and life was calm, yet they predate younger rocks that record extreme events. The Bass Formation, some of the only …

Experimental Study Of Gravitational Mixing Of Supercritical Co2, Dennis L. Newell, J. William Carey, Scott N. Backhaus, Peter Lichtner

Geosciences Faculty Publications

CO₂ injection into saline aquifers for sequestration will initially result in buoyant supercritical (sc)CO₂ trapped beneath the caprock seal. During this period, there is risk of CO₂ migration out of the reservoir along wellbore defects or fracture zones. Dissolution of the scCO₂ plume into brine results in solubility trapping and reduces this risk, but based on diffusion alone, this mechanism could take thousands of years. Gravitational (density-induced) mixing of CO₂-saturated brine is shown to significantly accelerate this process in computational studies, but few experimental efforts have confirmed the phenomenon. Here, constant-pressure, 3-dimensional bench-scale experiments …

Evidence For Cyclical Fractional Crystallization, Recharge, And Assimilation In Basalts Of The Kimama Drill Core, Central Snake River Plain, Idaho: 5.5-Million-Years Of Petrogenesis In A Mid-Crustal Sill Complex, Katherine E. Potter, John W. Shervais, Eric H. Christiansen, Scott K. Vetter

Geosciences Faculty Publications

Basalts erupted in the Snake River Plain of central Idaho and sampled in the Kimama drill core link eruptive processes to the construction of mafic intrusions over 5.5 Ma. Cyclic variations in basalt composition reveal temporal chemical heterogeneity related to fractional crystallization and the assimilation of previously-intruded mafic sills. A range of compositional types are identified within 1,912 m of continuous drill core: Snake River olivine tholeiite (SROT), low K SROT, high Fe-Ti, and evolved and high K-Fe lavas similar to those erupted at Craters of the Moon National Monument. Detailed lithologic and geophysical logs document 432 flow units comprising …