Geology Commons^™

Phase Equilibria, Compressibility, And Thermal Analysis Of Bastnaesite-(La), Richard Lee Rowland

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding basic material properties of rare earth element (REE) bearing minerals such as the temperatures and pressures at which different phases are thermodynamically stable and how they respond to changes in temperature and pressure can assist in understanding how economically viable deposits might form, thereby potentially leading to the discovery of new deposits. Bastnaesite is the most common REE bearing mineral mined. The lanthanum-fluoride end member, bastnaesite-(La), was synthesized. Synthetic bastnaesite-(La) and lanthanum oxyfluoride was investigated using thermal analysis at ambient pressure and high temperature through the methods of thermogravimetric analysis, differential scanning calorimetry, and heated stage powder X-ray diffraction. …

U–Pb Dating Of Cave Spar: A New Shallow Crust Landscape Evolution Tool, D. D. Decker, V. J. Ployak, Y. Asmeron, Matthew Lachniet

Geoscience Faculty Research

In carbonate terranes, rocks types that provide apatite are not available to effectively use apatite fission track (AFT) or (U/Th)‐He chronometry (AHe). Here we suggest that calcite cave spar can be an effective chronometer and complimentary to AFT and AHe thermochronometers in carbonate regions such as our study area, the Guadalupe Mountains of southeastern New Mexico, and west Texas. Our measured depth of cave spar deposition is 500 ± 250 m beneath the regional water table, formed at temperatures of 40° to 80°C, indicating that these caves and their spar crystals form near the supercritical CO2‐subcritical CO2 boundary where we …

Late Cretaceous Extensional Collapse Of The Southern Cordillera: Evidence From The Bristol And Granite Mountains, Se California, Lee Hess

UNLV Theses, Dissertations, Professional Papers, and Capstones

Demonstrating the regional extent of Late Cretaceous extensional collapse of western North America’s southern Cordillera is important to understanding the tectonic evolution of the Sevier-Laramide orogens, and the geodynamics of ancient and modern orogens and synconvergent extension. Documenting Late Cretaceous extension in the southern Cordillera requires looking through the extensive overprint by Cenozoic structures. Late Cretaceous extension in the eastern Mojave region has been inferred from geochronology and thermochronology studies, which document Late Cretaceous cooling of Mesozoic granitoid rocks, some of which were emplaced in the middle crust. Cooling histories from these rocks have also been interpreted to be a …

Environmental Changes Across The Early Mississippian Carbon Isotope Excursion, Dev Krishna Maharjan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Early Mississippian K–O (Kinderhookian-Osagean) δ13C excursion or TICE (mid-Tournaisian carbon isotope excursion) is characterized by an anomalous carbonate carbon isotope value of ≥5‰ that has been documented from numerous stratigraphic sections across the globe. This δ13C excursion coincides with global cooling and sea-level fall and predicts a significant change in seawater chemistry. However, sulfate sulfur isotope data across the K-O δ13C excursion reported in previous studies seem not to be responsive to the carbon cycle. Likewise, a recent study has documented a unidirectional increase in nitrogen isotopes across this excursion, which is not anticipated considering the amount of organic …

An Elemental Highway: Investigation Of A High Nickel Anomaly In Olivine From The Island Of Niihau, Hawaii, Alexander James Valentine

UNLV Theses, Dissertations, Professional Papers, and Capstones

The study of volcanic geochemistry is one of the main gateways for investigating the Earth’s mantle. One important topic in the field is that of nickel (Ni) in the mineral olivine. While Ni is a compatible element in olivine, its high concentration at a given MgO content is not well understood. A variety of hypotheses have been proposed, including attributing presence of Ni to pyroxenite source melting, contribution from the core, or variation in peridotite source melting. In addition to the other hypotheses, chemical diffusion may also be a mechanism for enriching olivine Ni concentration. Magnesium-iron (Mg-Fe) isotopic measurements have …

Characterizing Crystal Populations For The Petrogenesis Of The Post-Collapse Rhyolites In The Long Valley Caldera, California, William Joseph

UNLV Theses, Dissertations, Professional Papers, and Capstones

Post-collapse rhyolites of the Long Valley in eastern California are the product of remelting of crystal mush bodies via mafic rejuvenation following the eruption of the Bishop Tuff. This is supported by mineral textures and major element geochemistry from the Resurgent Dome rhyolite, the Moat rhyolite, the Hot Creek Flow, and the Deer Mountain rhyolite. New 40Ar/39Ar eruptive ages are reported for the Moat rhyolites (525 ka, 333 ka, 118 – 94 ka), Hot Creek Flow (312 – 295 ka), and the Deer Mountain rhyolite (65 ka). The initial post-collapse eruptions, resulting in the Resurgent Dome rhyolite, appear to be …

Assessing A Potential Paleothermal Anomaly Near A Salt Wall Using (U-Th)/He Thermochronology And Silica Cementation Analysis, Onion Creek, Utah, Richard Gregory Ness

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Onion Creek salt wall in Fisher Valley, Utah is an exposed salt structure that lies adjacent to sandstones of the Permian age Cutler Group. The thermal conductivity of salt is two to four times greater than other sedimentary rocks and has been shown to act as a regional conduit for heat flow which has implications for petroleum systems in hydrocarbon exploration. Numerical models predict that thermal anomalies should extend 1.5 times the radius of a salt structure into adjacent strata. I hypothesized that an elevated paleothermal anomaly exists in sandstones of the Cutler Group where they are located near …

Canovas Canyon Rhyolites, Jemez Volcanic Field, New Mexico: Discrete Source Magmas, Or A Potential Caldera Forming Magma System?, Penelope Marie Padmore

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Jemez volcanic field (JVF), New Mexico, is a caldera-forming volcanic field located at the junction of the Rio Grande Rift and the Jemez Lineament. The JVF is one of three large North American caldera-forming systems, including Long Valley, California and Yellowstone Plateau volcanic field, Wyoming, which have been active during the Quaternary. Because portions of the JVF are unusually well preserved, it offers a rare opportunity to study how such systems develop. Insight into the history of caldera-forming systems will contribute to the understanding of their potential future behavior. In the case of Yellowstone and Long Valley, that insight …

Patterns Of Synorogenic Sedimentation Associated With The Unroofing Of The Willard-Paris-Meade Thrust Sheets, Sevier Fold-Thrust Belt, Amanda Gentry

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Willard-Paris-Meade thrust is the oldest and western-most sheet to develop in the Wyoming salient of the Sevier fold-thrust belt. The 10-15 km thick thrust sheet was emplaced ~60 km eastward and included Jurassic-Triassic strata, mixed siliciclastic-carbonate upper Paleozoic strata, carbonate-rich lower Paleozoic strata, and quartzite-rich basal Cambrian to Neoproterozoic strata. Each stratigraphic interval has a distinctive detrital zircon (DZ) age signature, which can be used in provenance analysis of foreland basin fill. The thrust system had a long deformation history recorded by westward thickening and coarsening synorogenic strata. DZ U-Pb geochronology of 27 synorogenic samples collected from two transects …

Structural Evolution Of The Maynard Lake Fault Within The Left-Lateral Pahranagat Shear Zone, Nevada, Usa, Mahmud Mustafa Muhammad

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Pahranagat shear zone (PSZ) contains three ENE-striking left-lateral strike-slip faults: The Arrowhead Mine fault (AMF), Buckhorn fault (BF), and Maynard Lake fault (MLF) from north to south. This shear zone lies along the boundary between the northern and central Basin and Range physiographic sub-provinces (NBR-CBR). In addition, this zone is positioned SW of a regional strike-slip zone, the Caliente-Enterprise zone (CEZ), and surrounded by extensional domains with differences in timing and magnitude of extension. Hence, understanding the development of the PSZ, particularly the MLF, is essential to better understanding tectonic evolution of the boundary zone between the northern and …

Characterizing The Earliest Stages Of Partial Melting: A Study Of The Pyrometamorphic Aureole Of Miocene Mt. Perkins Pluton, Northwest Arizona, Mathew Beshears

UNLV Theses, Dissertations, Professional Papers, and Capstones

Partial melting is an important process in the evolution of continental crust. Due to its progressive nature, evidence of the early stages of partial melting is often overprinted by later, advanced stages of partial melting. Experimental work has provided a model for the early stages of partial melting, but is limited to timescales of hours to weeks. Pyrometamorphic environments within the contact aureole of mafic intrusions provide natural laboratories for the study of the earliest stages of partial melt production on geologic time scales of 102 collected along two traverses of the tilted pyrometamorphic aureole of the Mt. Perkins pluton …

(U-Th)/He Studies Of The Southern Snake Range Metamorphic Core Complex, Nv And Gypsum Valley Salt Wall, Paradox Basin, Co, Usa, Sarah Lynn Evans

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation presents three studies that investigate extension in the Southern Snake Range (SSR) metamorphic core complex (MCC) of east-central Nevada and a thermal anomaly associated with the Gypsum Valley salt wall (GVSW) of southwestern Colorado. Low temperature thermochronologic studies using the (U-Th)/He system have been applied in numerous geologic settings to understand erosional and tectonic denudation processes. Two of the studies presented use (U-Th)/He thermochronology, combined with other techniques, to investigate the extensional history of the SSR and the extent of the GVSW thermal anomaly. Both of these studies present novel methods for understanding the thermal histories of the …

Glass Shards At Pinnacle Point Rock Shelter 5-~6, South Africa: Are They From The Last Super-~Eruption Of Toba?, Amber Elizabeth Ciravolo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cryptotephra, in the form of individual glass shards, have been discovered in paleoarchaeological site PP5-6 North at Pinnacle Point, Western Cape, South Africa. This marks the first documentation of cryptotephra in a South African paleoarchaeological site. PP5-6 North is a rock shelter in the cliffs along the coast of the Western Cape and is one of a series of caves and rock shelters at Pinnacle Point that were inhabited by early modern humans. The presence of cryptotephra at PP5-6 is an important discovery in terms of tephra preservation in cave deposits as well as the possibility of tephra being present …

Rewetting Of Artificially Desiccated Soils: Effect Of Gravity On Vapor-Phase Diffusion, Taylor Arland Ball

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil desiccation has been suggested as an economically viable alternative for stabilizing water soluble contaminants in deep vadose zones such as at the Hanford Site. This approach would result in a large volume of the vadose zone being dried out in an effort to eliminate the transport mechanism for aqueous phase contaminants. Protecting the top and sides of the desiccated vadose zone from rewetting is a realistic possibility; however, it would be extremely difficult to restrict the upward migration of water from beneath the desiccated zone. One scenario related to the rewetting of the desiccated soil involves the upward migration …

Characterization Of Gold And Related Mineralization At The North Bullion Carlin System, Railroad Project, A Nevada Carlin-~Type Gold Prospect, Melanie Nicole Newton

UNLV Theses, Dissertations, Professional Papers, and Capstones

A study of the North Bullion Carlin system, a Nevada Carlin-type gold prospect located on trend with the large Carlin-type gold deposits (CTGD) of the Carlin Trend, identified characteristics of ore and alteration mineralization, mineral paragenesis, and pyrite and whole rock geochemistry that are similar to characteristics that typify Carlin-type gold deposits. The North Bullion Carlin system is hosted in Devonian shelf carbonates and the Mississippian overlap assemblage, host rocks that are different from typical CTGD shelf-slope carbonate assemblage host rocks. The mineralogy and ore-stage gold-bearing pyrite rims at North Bullion are not as well developed as they are in …

Ediacaran Ocean Redox Evolution, Swapan Kumar Sahoo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The relative role that environmental versus intrinsic biological factors played in

shaping the history of life on Earth is a fundamental but unanswered question in the

natural sciences. Most famously, it has been heavily debated if the emergence and

diversification of early animals during the Ediacaran Period (ca. 635–541 Ma) was tied to

a rise in atmospheric-oceanic oxygen levels. Temporally discontinuous geochemical data and patchy fossil record in literature are inadequate to chart the Ediacaran redox history and its causal relationship with the biotic evolution. My PhD study aims for a multiproxy geochemical record within a well-established stratigraphic framework of …

Dissolution Of Nontronite In Low Water Activity Brines And Implications For The Aqueous History Of Mars, Michael Henry Steiner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Water is essential to life on Earth and is likely to play a role in determining the habitability of other planets. Pure liquid water is not stable on the surface of Mars but brines can temporarily remain liquid, and increasing evidence suggests the presence of recent liquid water, including brines, on Mars. Brines can host life at temperatures as low as -30 ºC and some organisms can live at activities of water as low as 0.61. Therefore, if brines have been present on Mars, they may act as habitable environments.

The Fe-rich smectite nontronite, (CaO0.5,Na)0.3 Fe3+2(Si,Al)4O10(OH)2·nH2O, has been detected on …

Testing Established Models Of Hydrothermal Fluid Distribution Around Porphyry Deposits: The Application Of Fluid Inclusion Research To Porphyry Deposit Exploration, Wyatt Moyer Bain

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Kabba porphyry copper prospect in northwestern Arizona contains two zones of porphyry style mineralization and alteration, which are spatially separated by a north-south trending normal fault. These two zones are referred to as the Kabba footwall and hanging wall and are hypothesized to represent the root and intermediate depth levels of the same porphyry-like hydrothermal system, respectively. If this hypothesis is correct, then fluid inclusions found in the hanging wall and footwall should have the physical and chemical characteristics of fluid inclusions in the root and intermediate depth levels of other known porphyry deposits. Vein and alteration petrography, fluid …

An Investigation Into Transitions In Clay Mineral Chemistry On Mars, Seth Gainey

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation is comprised of three studies investigating clay mineralogy on, or near the martian surface, with an introductory chapter, introducing and linking the three studies. Chapter two is on the subject of clay mineral synthesis, including Fe/Mg clay minerals which have been detected at multiple locations across the southern highlands. These Fe/Mg clay minerals have been previously interpreted as forming in anoxic/reducing environments, conducive to the preservation of organic matter. The results of this study suggest that the previous interpretation of Fe/Mg-rich clay as requiring anoxic/reducing conditions may not be accurate, as the minor presence of Mg (below what …

Kinematics And Timing Of The Miocene-Quaternary Deformation In Nellis Dunes Recreational Area, Nevada, Shaimaa Abdelhaleem

UNLV Theses, Dissertations, Professional Papers, and Capstones

The kinematics and origin of transfer, accommodation and strike-slip zones is of paramount significance in understanding continental extension. The Las Vegas Valley Shear Zone (LVVSZ) is a NW-striking right-lateral fault system in the central Basin and Range province. Despite its prominence among the structures of the region and its role in the regional tectonic development, little is understood about its eastern portion. The inadequately constrained trace of the LVVSZ along its eastern part contributes largely to the ambiguity of the time activity and role of the LVVSZ. The eastern part of LVVSZ lies in Nellis Dunes Recreational Area (NDRA), north …

Stable Isotope Analysis Of Bison Latifrons And Paleoecological Inferences, Fabian Ceron Hardy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bison latifrons was a large Pleistocene herbivore that is traditionally hypothesized to have been adapted to living in forest openings and woodlands. According to this view, the species was primarily a browser of high-growing, woody plants. Very little isotopic work has been conducted on this species, and there have been no prior studies of high altitude localities containing this species. This study aims to address both of these issues.

B. latifrons is known from sites in several states, including California, Idaho, Colorado, Nevada, and Florida, among others. These sites provide diverse examples of this species’ habitat and the opportunity to …

Trace Element Variations In A Stalagmite From Southwest Mexico: Implications For Paleoclimate, Chad Michael Crotty

UNLV Theses, Dissertations, Professional Papers, and Capstones

The combination of stable isotope and trace element concentrations in speleothems has been shown to be a valuable indicator for interpreting paleoclimatic conditions. Anomalous spikes in trace element concentrations have also been shown to indicate anthropogenic environmental changes to the surface, such as deforestation events. In this study, trace element concentrations (24Mg, 25Mg, 84Sr, 88Sr, 137Ba, and 238U) of a stalagmite (JX-6) from Juxtlahuaca Cave, in southwestern Mexico, were measured using an inductively coupled plasma mass spectrometer (ICP-MS). These trace element concentrations were compared to previously analyzed δ18O and δ13C values from JX-6, and to the results of previous studies …

Modeling Background Radiation Using Geochemical Data, Kara Marsac

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerial gamma ray surveys have many applications in geology and science in general, such as locating mining prospects, defining radioactive plumes, and detecting nuclear weapons. Unfortunately there is currently no simple way to separate the natural gamma radiation of soil and rocks from that of contaminants such as radioactive plumes. This project used geochemical data (uranium, potassium and thorium concentrations) collected from national databases, private companies, and the NURE (National Uranium Resource Evaluation) Survey, to create forward models of exposure rates measured by aerial gamma ray surveys. We developed these techniques using an area in north central Arizona known as …

Carbon Isotope Variations Associated With A Middle Ordovician Karstic Unconformity, Patricia Suzanne Williams

UNLV Theses, Dissertations, Professional Papers, and Capstones

Large negative carbon isotope (δ¹³C) excursions have been documented from late Neoproterozoic-Paleozoic successions. These δ¹³C excursions have been widely used for regional and global stratigraphic correlation, particularly in strata with limited paleontological and radiometric age controls. Recent studies, however, argued that some negative δ¹³C excursions from stratigraphic record may have been resulted from meteoric/burial diagenesis, which commonly shifts both carbon and oxygen isotopes toward lower values. Testing the diagenetic origin of δ¹³C excursions in stratigraphic successions without independent stratigraphic framework has been difficult because it evolves into circular arguments about stratigraphic completeness …

Ore Classification And Breccia Formation In The 144 Zone Gold Deposit: A Chemical Replacement Model, Bare Mountain Range, Nevada, William Thomas Fischer

UNLV Theses, Dissertations, Professional Papers, and Capstones

The 144 Zone is an oxidized, breccia-hosted, disseminated gold deposit that formed along the contact between Early Cambrian Carrara Formation limestone and overlying Bonanza King Formation dolomite within the Bare Mountain range in southern Nevada. Gold mineralization occurs within a breccia body that contains a variety of breccia types. Research goals of this project included classifying clay, oxide and other minerals as well as breccia types to identify the habits of gold mineralization and the minerals associated with gold. Research was also aimed at determining the paragenesis of Au mineralization and brecciation in the 144 Zone. Underground mapping provided spatial …

Subalklaine Volcanism In The Eastern Basin And Range Province: Examples From The Miocene Mccullough Range Volcanic Field And The Pliocene To Holocene Black Rock Desert Volcanic Field, Racheal Leighann Johnsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation is composed of three papers that apply geologic mapping, whole rock geochemical and isotopic analysis, and mineral chemistry to describe two large, long-lived (~6 million years), and compositionally heterogeneous volcanic fields and posit sources of the rock types present in each. These fields are the McCullough Range in southern Nevada, which was a locus of volcanic activity from ~19 - 12 Ma and the Black Rock Desert volcanic field in west-central Utah, which began forming at ~6 Ma and is still active today, with the most recent eruption occurring ~720 years ago.

Chapter Two is composed of a …

Thermal Impacts Of Salt On Sandstones And Mudstones In The Lusitanian Basin, Portugal, Brett Perry

UNLV Theses, Dissertations, Professional Papers, and Capstones

In order to assess the impact of salt structures on paleotemperatures in adjacent sedimentary rocks, a field based study which quantified thermally driven diagenetic products as a function of distance from salt was undertaken. Several salt diapirs are now exposed at the surface of the Earth within the Lusitanian Basin and offered a unique opportunity to document paleothermal anomalies by studying thermally controlled diagenesis in adjacent, exposed Upper Jurassic rocks. Four transects were chosen within Upper Jurassic rocks that contained both sandstones and mudstones. Quartz cementation and albitization of feldspars, both of which are thermally driven processes, were quantified in …

New Early Miocene 40ar/39ar Ages For Nakwai, Northwest Kenya, Africa, And Paleontological Analysis Of Meroehyrax Kyongoi Dentition, Dawn Elena Reynoso

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nakwai is a fossiliferous region in the Turkana Basin of northwestern Kenya. Until recently the only ages for the Nakwai formation were based on biostratigraphic correlation with Losodok; a late Oligocene site located to the north of Nakwai. The new 40Ar/39Ar ages in this study range from 23 Ma to 15 Ma and constrain the upper portions of the Nakwai section to the early Miocene. These ages make it the only securely dated fossil locality in the region that represents the earliest Miocene; all of the other early Miocene fossil localities date back to ~20 Ma or younger. The time …

Estimating Aquifer Characteristics And Identification Of A Sub-Basin For Artificial Storage And Recovery, Northeastern Ivanpah Valley, Nevada, Nikolas James Taranik

UNLV Theses, Dissertations, Professional Papers, and Capstones

The identification of a structurally controlled sub-basin with impediments to groundwater flow within Southern Nevada could provide a favorable area for artificial recharge and storage of native or imported water, extending the water supply of Southern Nevada. For this purpose, the area of northeastern Ivanpah Valley was investigated to determine the ability of the aquifer to accept and recover stored water, if acceptable water quality existed in the potential sub-basin storage area, and if structural controls impeded and isolated groundwater flow. The results found evidence the proposed sub-basin is structurally isolated by the McCullough, Roach, and Stateline Faults, which was …

Kinematics And Timing Of Superposed Deformation In The Funeral Mountains Metamorphic Core Complex, Death Valley, Ca, Katrina Marie Sauer

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Funeral Mountains metamorphic core complex (FMMCC) in Death Valley, California exposes middle to lower crustal rocks of the Sevier-Laramide orogen in the footwall of the Miocene Boundary Canyon detachment. The structurally deepest rocks in the FMMCC are exposed in Monarch Canyon, where the Meso- to Neoproterozoic metasedimentary rocks record upper amphibolite facies metamorphism with migmatites developed at the deepest levels. Distributed ductile deformation and stratigraphically-localized high-strain zones, termed intracore shear zones, are responsible for attenuation and local stratigraphic omission during top-northwest non-coaxial deformation. The structurally deepest Monarch Spring shear zone (MSSZ) juxtaposes the migmatitic paragneisses below against greenschist to …