Geology Commons^™

Melting In The Mantle Wedge: Quantifying The Effects Of Crustal Morphology And Viscous Decoupling On Melt Production With Application To The Cascadia Subduction Zone, Jiaming Yang

Dissertations and Theses

Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting and decompression melting due to upward flow. The distribution of melting is sensitive to temperature, the pattern of flow, and the pressure in the mantle wedge. The arc front is the surface manifestation of partial melting in the mantle wedge and is characterized by a narrow chain of active volcanoes that migrate in time. The conventional interpretation is that changes in slab dip angle lead to changes in the arc …

40ar/39ar Ages And Zircon Petrochronology For The Rear Arc Of The Izu-Bonin-Marianas Intra-Oceanic Subduction Zone, Graham Dm Andrews

Faculty & Staff Scholarship

Long-lived intra-oceanic arcs of Izu-Bonin-Marianas (IBM)-type are built on thick, granodioritic crust formed in the absence of pre-existing continental crust. International Ocean Discovery Program Expedition 350, Site U1437, explored the IBM rear arc to better understand continental crust formation in arcs. Detailed petrochronological (U–Pb geochronology combined with trace elements, oxygen and hafnium isotopes) characterizations of zircon from Site U1437 were carried out, taking care to exclude potential contaminants by (1) comparison of zircon ages with ship-board palaeomagnetic and biostratigraphic ages and 40Ar/39Ar geochronology, (2) analysing zircon from drill muds for comparison, (3) selectively carrying out in situ analysis in petrographic …

The Dynamic Relationship Between The Bear River, Quaternary Basaltic Center, Normal Faults, And The Resulting Rearrangement Of Rivers In The Northeast Edge Of The Great Basin, Southeast Idaho, Brady Utley

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

The objective of this research project in Gem Valley graben, southeast Idaho is to identify the location, age and history of the Quaternary diversion of the Bear River into paleo-Lake Thatcher, and then into the Lake Bonneville basin from the Columbia River basin. Mapping, geochemical analysis, cross-cutting relationships, and five new age determinations, together with prior published research, shed new light on the complex history of interaction between the volcanic rocks, rivers, lakes, and faults in Gem Valley. Research goals were to test the hypothesis that local faulting and volcanism drove the diversion of the Bear River and controlled the …

Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee

Earth and Planetary Sciences ETDs

Volatiles (N2, CO2, and He) are released by volcanism and hydrothermal activity during continental rifting and subduction processes. Analyses of volatile components have been conducted to obtain gas contents (CO2, SO2, H2S, N2, Ar, He, and so on), stable isotope compositions (δ13C, δ15N, and so on), and noble gas isotopes (3He/4He, 40Ar/36Ar, and so on). This dissertation includes four chapters to report new nitrogen isotope fractionation factors of bubbling gases during gas-water transfer at various water temperatures (Chapter 1), first measurements of massive amounts of CO2 released by incipient continental rifting in the Magadi and Natron Basin, East African Rift …

Origin Of Primitive Ocean Island Basalts By Crustal Gabbro Assimilation And Multiple Recharge Of Plume-Derived Melts, Anastassia Y. Borisova, Wendy A. Bohrson, Michel Grégoire

All Faculty Scholarship for the College of the Sciences

Chemical Geodynamics relies on a paradigm that the isotopic composition of ocean island basalt (OIB) represents equilibrium with its primary mantle sources. However, the discovery of huge isotopic heterogeneity within olivine‐hosted melt inclusions in primitive basalts from Kerguelen, Iceland, Hawaii and South Pacific Polynesia islands implies open‐system behavior of OIBs, where during magma residence and transport, basaltic melts are contaminated by surrounding lithosphere. To constrain the processes of crustal assimilation by OIBs, we employed the Magma Chamber Simulator (MCS), an energy‐constrained thermodynamic model of recharge, assimilation and fractional crystallization. For a case study of the 21–19 Ma basaltic series, the …

A High‐Resolution Atmospheric Dust Record For 1810–2004 A.D. Derived From An Ice Core In Eastern Tien Shan, Central Asia, Wangbin Zhang, Shugui Hou, Yaping Liu, Shuang-Ye Wu, Wenling An, Hongxi Pang, Chaomin Wang

Department of Earth, Environment and Sustainability Faculty Publications

Centennial‐scale, high‐resolution records of atmospheric dust conditions are rare in the arid and semiarid regions of central Asia, limiting our understanding of the regional climate and environmental changes and their potential driving forces. In this paper, we present an annually resolved atmospheric dust record covering the period of 1810–2004 A.D., reconstructed from an ice core retrieved at 4512 m above sea level from the Miaoergou Glacier in the eastern Tien Shan. The time series of dust flux for the past 195 years shows three periods of relatively low values (i.e., 1810–1829 A.D., 1863–1940 A.D., and 1979–2004 A.D.) and two periods …

A Case Study In Basement And Surface Structure Relationships And Their Implications For Fault Reactivation, Sawtooth Range, Mt, Jason M. Palu

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The reactivation of pre-existing basement structures affects the geometry of subsequent deformation structures. A case study analyzing the results of these interactions can be used to examine multiple fold-thrust systems and lead to valuable deformation predictions. These predictions include the potential for hydrocarbon traps or seismic risk in an actively deforming area. This case study examined the development of structures close to the Augusta Syncline in the Sawtooth Range, Montana (USA), using: 1) an ArcGIS map of basement structures, based on analysis of gravimetric and aeromagnetic data, seismic data, and well logs; 2) an ArcGIS map of the surface deformation …

Gravitational Study Of The Hastings Salt Dome And Associated Faults In Brazoria And Galveston Counties,Texas, Francis C. Okocha

Electronic Theses and Dissertations

Salt domes are important geological structures because they are potential major hydrocarbon traps and have a profound effect on overlying strata in the subsurface. Over five hundred salt domes have been located on the United States Gulf Coast region, including the Hastings Salt Dome. Hastings Oil Field is located about 40.2 km (25 miles) southeast of Houston, Texas. The Hasting oil field was discovered in 1934 and it was considered the largest oil reserve on the Gulf Coast. Its peak production of 75,000 BOPD (barrels of oil per day) was recorded in 1977 and it had a cumulative production of …

Structural And Stratigraphic Reconstruction Of The Whiting Dome Salt Structure In Viosca Knoll-Mississippi Canyon, Gom, Using 3d Seismic Data, Matthew R. Worrell

Electronic Theses and Dissertations

Understanding the complexities of salt tectonics is one of the most important factors regarding seismic interpretation of stratigraphy, structure, and geomorphology in the Gulf of Mexico. Evaluating the processes affecting recent mobilization of salt in the shallow, well-imaged section can help provide analogues for older, similar occurrences in the deeper section, thereby providing structural models for the autochthonous salt and its effect on stratigraphy and even potential timing and migration issues of hydrocarbons.

Progradation of delta front and shelf to slope transitional sediments has expulsed and emplaced an allochthonous salt structure (Whiting Dome) in the Viosca Knoll and Mississippi Canyon …

Basement And Cover Structural Analysis Along The Eagle River Gorge, Sawatch Range, Colorado, Kaitlin Lee Askelson

Electronic Theses and Dissertations

The Sawatch Range within the Rocky Mountains of central Colorado exposes Paleoproterozoic basement and overlying Paleozoic sedimentary rocks with a complex history of ductile and brittle deformation.

The goal of this study is to conduct analyses of brittle structures that occur in the basement and cover units to determine geometric relationships between the structures, provide a detailed description of structures and refine a geologic history for structures along the basement-cover contact in the northeastern Sawatch Range along the Eagle River canyon and U.S. Highway 24 from Red Cliff to Gilman, Colorado. Paleoproterozoic basement rocks include the Cross Creek granite, diorites, …

Impacts On The Stakeholders Of The Nexus Pipeline, Jessica A. Speweike

Honors Projects

This journalistic feature covers the different impacts on those individuals who are involved with or affected by the Nexus Gas Transmission pipeline. Testimony from Ohio landowners, activists, scientists and public officials cover a variety of opinions and concerns raised by the pipeline. Private property rights, environmental impact, and possible economic implications are detailed by those who have been involved with the Nexus pipeline since its early stages of implementation.

Lithospheric Evaluation Of The Mid-Continental Rift System In Iowa From A Gravity And Magnetic Analysis, Moamen Mohamed Almaz

Graduate Theses/Dissertations

The Proterozoic Midcontinent Rift System (MCRS) is considered one of the most important tectonic features in North America and was formed during a continental breakup event at 1.1 Ga (billion years). The MCRS is totally covered by Phanerozoic sedimentary rocks except in the Lake Superior region. Consequently, the geological characteristics of the MCRS are primarily inferred from extrapolations from the outcrop areas, drill holes, and from a variety of geophysical investigations. Iowa has a large segment of the MCRS which to date has only been partially investigated geophysically with little information regarding the lower crustal and upper mantle structure under …

Impact Of Icebergs On Net Primary Productivity In The Southern Ocean, Shuang-Ye Wu, Shugui Hou

Department of Earth, Environment and Sustainability Faculty Publications

Productivity in the Southern Ocean (SO) is iron-limited, and supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine environment. However, recent studies show that icebergs could provide a comparable amount of bioavailable iron to the SO as aeolian dust. In addition, small-scale areal studies suggest increased concentrations of chlorophyll, krill, and seabirds surrounding icebergs. Based on previous research, this study aims to examine whether iceberg occurrence has a significant impact on marine productivity at the scale of the SO, using remote sensing data of iceberg occurrences and ocean net primary productivity …

Timing Of Mid-Crustal Ductile Extension In The Northern Snake Range Metamorphic Core Complex, Nevada: Evidence From U/Pb Zircon Ages, Jeffrey Lee, Terrence Blackburn, Scott Johnston

All Faculty Scholarship for the College of the Sciences

Metamorphic core complexes within the western U.S. record a history of Cenozoic ductile and brittle extensional deformation, metamorphism, magmatism, and exhumation within the footwalls of high-angle Basin and Range normal faults. In models proposed for the formation of metamorphic core complexes there is a close temporal and spatial link between upper crustal normal faulting, lower crustal ductile extension and flow, and detachment faulting. To provide constraints on the timing of ductile extension in the northern Snake Range metamorphic core complex (Nevada) and thereby test these models, we present new 238U-206Pb dates on zircons from both deformed and undeformed rhyolite dikes …

Delayed Warming Hiatus Over The Tibetan Plateau, Wenling An, Shugui Hou, Yongyun Hu, Shuang-Ye Wu

Department of Earth, Environment and Sustainability Faculty Publications

A reduction in the warming rate for the global surface temperature since the late 1990s has attracted much attention and caused a great deal of controversy. During the same time period, however, most previous studies have reported enhanced warming over the Tibetan Plateau (TP). In this study we further examined the temperature trend of the TP and surrounding areas based on the homogenized temperature records for the period 1980–2014, we found that for the TP regions lower than 4000 m the warming rate has started to slow down since the late 1990s, a similar pattern consistent with the whole China …

Ground-Rupturing Earthquakes On The Northern Big Bend Of The San Andreas Fault, California, 800 A.D. To Present, Katherine Scharer, Ray J. Weldon Ii, Glenn Biasi, Ashley Streig, Thomas Fumal

Geology Faculty Publications and Presentations

Paleoseismic data on the timing of ground-rupturing earthquakes constrain the recurrence behavior of active faults and can provide insight on the rupture history of a fault if earthquakes dated at neighboring sites overlap in age and are considered correlative. This study presents the evidence and ages for 11 earthquakes that occurred along the Big Bend section of the southern San Andreas Fault at the Frazier Mountain paleoseismic site. The most recent earthquake to rupture the site was the Mw7.7–7.9 Fort Tejon earthquake of 1857. We use over 30 trench excavations to document the structural and sedimentological evolution of a small …

Unusual Geologic Evidence Of Coeval Seismic Shaking And Tsunamis Shows Variability In Earthquake Size And Recurrence In The Area Of The Giant 1960 Chile Earthquake, M. Cisternas, E. Garrett, R. Wesson, T. Dura, Lisa L. Ely

All Faculty Scholarship for the College of the Sciences

An uncommon coastal sedimentary record combines evidence for seismic shaking and coincident tsunami inundation since AD 1000 in the region of the largest earthquake recorded instrumentally: the giant 1960 southern Chile earthquake (Mw 9.5). The record reveals significant variability in the size and recurrence of megathrust earthquakes and ensuing tsunamis along this part of the Nazca-South American plate boundary. A 500-m long coastal outcrop on Isla Chiloé, midway along the 1960 rupture, provides continuous exposure of soil horizons buried locally by debris-flow diamicts and extensively by tsunami sand sheets. The diamicts flattened plants that yield geologically precise ages to correlate …

The Tuscaloosa Marine Shale: Geologic History, Depositional Analysis, And Exploration Potential, Jessica D. Pair

Electronic Theses and Dissertations

The Tuscaloosa Marine Shale (TMS) was deposited across southern Louisiana and Mississippi during the Upper Cretaceous. The study focuses on a core region containing vast deposits of Cretaceous-aged sediments that have economic importance for oil and gas exploration. This region has been conventionally drilled for decades, focusing on the recovery of the Cretaceous hydrocarbons. Explorers within this region had traditionally targeted the massive sand units of the Lower and Upper Tuscaloosa Group while neglecting the middle Tuscaloosa Marine Shale unit. With the onset of unconventional drilling technology, new explorers to the region have begun to delineate the Tuscaloosa Marine Shale’s …

Explaining Creep-Like Deformation In The Marmara Sea: Results From Avo-Derived Vp/Vs And Pore Pressure Analysis, Rahmi M. Bolat

Earth Sciences Theses and Dissertations

Recent studies suggest that high pore pressures have caused seafloor creep-like deformation and slope failure in the Marmara Sea (e.g. Shillington et al., 2012). Stratigraphic analysis provides evidence for creep-like deformation in Marmara Sea sediments, however, no detailed quantitative geophysical analysis has been conducted to determine whether elevated fluid pressures exist in the Marmara Sea sediments today, or if these sediments are potentially near-critically stressed. If fluid pressures are high and the sediments are close to failure, only minor ground accelerations from earthquakes along the active Northern Anatolian Fault might trigger failure. For this study, I use high resolution multichannel …

Structural Analysis Of A Triangle Zone Culmination, Comb Rock, Lewis And Clark County, Montana, Shane S. Fussell

Graduate Student Theses, Dissertations, & Professional Papers

A triangle zone is a structure commonly found at the leading edge of a thrust belt, characterized by a triangular cross-section of thrust faults. In the Montana triangle zone, west-dipping thrust faults intersect east-dipping ones above a regional detachment fault. Most studies of triangle zones focus on the structure in a cross-sectional sense, but little work addresses variations along the trend. The Canadian Rocky Mountain triangle zone has long been a productive petroleum province, so understanding the southern extent of this zone, where it enters Montana, is of interest for economic purposes as well as geologic understanding. Previous studies have …

Potential Field Modeling Across The Neodymium Line Defining The Paleoproterozoic-Mesoproterozoic Boundary Of The Southeastern Margin Of Laurentia, Rachel Lauren Durham

Theses and Dissertations--Earth and Environmental Sciences

A zone of high magnetization along the SE margin of Paleoproterozoic Laurentia in the United States is indicated by magnetic anomaly data. The SE edge corresponds to the geochemical Neodymium mantle derivation model age (T_DM) boundary and the entire anomaly overlies the Paleoproterozoic Mazatzal Province. Two-dimensional gravity and magnetic models across the Nd boundary are created with Moho constrained from receiver functions with gravity, sedimentary thickness and the base of the crustal magnetization. Upper crustal magnetization does not show strong variation across this boundary and much of the strong magnetization appears to lie in the middle crust. Using …

Pressure Dependence Of Polycrystalline Magnesite And Dolomite, Cole Blasko

Williams Honors College, Honors Research Projects

Intermediate depth (170-400 km) deep focus earthquakes are observed in subducting slabs, but unlike shallow (50-170 km) and deep (400-660 km) deep focus earthquakes, the mechanism(s) responsible for them are not clear. Two common alteration products observed in peridotites, magnesite and dolomite, are stable along the pressure-temperature path of a subducting slab. Low pressure experiments indicate that these minerals are weaker than olivine, but there are no data about the pressure dependence of the strength of magnesite or dolomite. Magnesite and dolomite cylinders (1mm by 1mm) were deformed in stacked series to 25-30% strain using the deformation-DIA (DDIA) at Argonne …

Mechanisms Of Shear Zone Localization And Raman Thermobarometry In Spinel Peridotites From The Alpine Fault, New Zealand, Emily J. Lubicich

Dissertations and Theses

A suite of xenoliths from two localities on South Island, New Zealand, exhibit rare microstructures and provide information on deformation during the early stages of development of the Alpine Fault. The first set of samples has evidence of dislocation creep with subgrains, recrystallized grains, undulose extinction and a lattice preferred orientation. These samples also show evidence of post deformation static grain growth with polygonal grains, 120° triple junctions, and euhedral grains within larger grains of the same phase. Samples from the second locality also show evidence of dislocation creep but with minimal static grain growth. This set also has a …

Surface Offset And Slip Rates For The Winter Rim Fault System In The Summer Lake Basin, Oregon, Jennifer Hall

All Master's Theses

The 66-km-long Winter Rim Fault (WRF) system, located in the northwestern Basin and Range Province, encompasses several Holocene fault scarps within the Summer Lake basin that include the WRF system, a normal fault divided into three segments: Slide Mountain (SMF), Winter Ridge, and Ana River (ARF), and the newly-mapped Thousand Springs fault (TSF). The current least-compressive stress field is oriented ~264° (Crider, 2001). The USGS estimates a slip rate of 0.43 mm/yr, earthquake magnitudes of 6.5-7.19, and recurrence interval of 3.1 ka (Crone et al., 2009). However, these estimates are only based upon ARF and the unfavorably slip-oriented SMF. With …

Archived Rock Samples From Jane Selverstone's Research Collection, Jane Selverstone

Earth and Planetary Sciences Faculty and Staff Publications

This Excel spreadsheet lists all of the rock samples from Jane Selverstone's research collection that have been archived into the Earth and Planetary Sciences Collections at the University of New Mexico. All samples are listed by original (published) sample number and by an affiliated International GeoSample Number. Samples are grouped by research project, and doi information is given for all publications resulting from work on each project. Rock samples include various combinations of hand specimens, powders, thin sections, and billets from which thin sections were prepared. Information is included to identify the drawers within which each sample can be found …

Characterization And Delineation Of Karst Geohazards Along Rm652 Using Electrical Resistivity Tomography, Culberson County, Texas, Adam F. Majzoub

Electronic Theses and Dissertations

The Delaware Basin of West Texas and southeastern New Mexico is the major western subdivision of the Permian Basin and a northern extension of the Chihuahuan Desert. The major evaporite unit within the Delaware Basin is the Castile Formation, which consists of gypsum/anhydrite and is highly susceptible to dissolution and karsting. Manifestations of karst within the Castile outcrop are abundant and include sinkholes, subsidence features and caves, both epigene and hypogene in origin.

Land reconnaissance surveys conducted during the summer of 2015 documented abundant karst landforms in close proximity to a major thoroughfare, RM 652, in Culberson County, Texas. 2D …

Future Changes In Mean And Extreme Monsoon Precipitation In The Middle And Lower Yangtze River Basin, China, In The Cmip5 Models, Yanjuan Wu, Shuang-Ye Wu, Jiahong Wen, Felipe Tagle, Ming Xu, Jianguo Tan

Department of Earth, Environment and Sustainability Faculty Publications

In this study, the potential future changes of mean and extreme precipitation in the middle and lower Yangtze River basin (MLYRB), eastern China, are assessed using the models of phase 5 of the Coupled Model Intercomparison Project (CMIP5). Historical model simulations are first compared with observations in order to evaluate model performance. In general, the models simulate the precipitation mean and frequency better than the precipitation intensity and extremes, but still have difficulty capturing precipitation patterns over complex terrains. They tend to overestimate precipitation mean, frequency, and intensity while underestimating the extremes. After correcting for model biases, the spatial variation …

Birth And Evolution Of The Rio Grande Fluvial System In The Last 8 Ma:Progressive Downward Integration And Interplay Between Tectonics, Volcanism, Climate, And River Evolution, Marisa N. Repasch

Earth and Planetary Sciences ETDs

The Rio Grande-Rio Chama (RG-RC) fluvial system has evolved dramatically over the last 8 Ma, undergoing channel migrations, drainage capture and integration events, volcanic damming, and carving and refilling of paleocanyons. Volcanism concurrent with the development of the river system provides a unique opportunity to apply multiple geochronometers to the study of its incision and drainage evolution. This paper reports 19 new ⁴⁰Ar/³⁹Ar basalt ages and 19 detrital mineral samples (zircon and sanidine) collected from RG-RC alluvium overlain by dated basalt flows in the context of a compilation of published ⁴⁰Ar/³⁹Ar basalt ages. The …

Possible Recent Warming Hiatus On The Northwestern Tibetan Plateau Derived From Ice Core Records, Wenling An, Shugui Hou, Wangbin Zhang, Shuang-Ye Wu, Hao Xu, Hongxi Pang, Yetang Wang, Yaping Liu

Department of Earth, Environment and Sustainability Faculty Publications

Many studies have reported enhanced warming trend on the Tibetan Plateau (TP), even during the warming hiatus period. However, most of these studies are based on instrumental data largely collected from the eastern TP, whereas the temperature trend over the extensive northwestern TP remains uncertain due to few meteorological stations. Here we combined the stable isotopic δ¹⁸O record of an ice core recovered in 2012 from the Chongce glacier with the δ¹⁸O records of two other ice cores (i.e., Muztagata and Zangser Kangri) in the same region to establish a regional temperature series for the northwestern …

Geologic, Geochemical, And Geophysical Characterization Of The Gold Deposits Of The Horseshoe Bend Mining District, Idaho: Building A Four Dimensional Model For Ore Exploration, Joshua Ekhoff

Boise State University Theses and Dissertations

The Eocene aged Trans-Challis Fault System of central Idaho provides the tectonic and magmatic framework for a series of Au-Ag and Cu-Mo ore deposits. From its northernmost extension near Butte, Montana to its southwestern terminus in the Boise Basin of south-central Idaho the Trans-Challis Fault System is associated with some of the richest precious metal deposits found in Idaho. However, the southernmost tip of the Trans-Challis Fault System, composed of the Horseshoe Bend and Pearl mining districts, remains understudied, receiving little economic or academic attention. As a result, how the Pearl to Horseshoe Bend mining districts fit within the established …