Earth Sciences Commons^™

Craters Of The Moon National Monument Basalts As Unshocked Compositional And Weathering Analogs For Martian Rocks And Meteorites, Christopher T. Adcock, Arya Udry, Elisabeth M. Hausrath, Oliver Tschauner

Geoscience Faculty Research

The availability of terrestrial sites that are martian analogs allows researchers to investigate Mars using knowledge gained on Earth. Among the terrestrial analog sites for Mars is Craters of the Moon National Monument (COTM) in Idaho, U.S.A. Craters of the Moon National Monument is home to over 60 basalt lava flows, many of which have been dated from 2050 to 18 340 years before present (y.b.p.). Following previous authors, we examined the chemistry and petrogenesis of COTM basalts compared to basaltic martian rocks, martian meteorites, and meteorite clasts, and then examined the results of chemical weathering of the basaltic flows. …

Humans Thrived In South Africa Through The Toba Eruption About 74,000 Years Ago, Eugene I. Smith, Zenobia Jacobs, Racheal Johnsen, Minghua Ren, Erich C. Fisher, Simen Oestmo, Jayne Wilkins, Jacob A. Harris, Panagiotis Karkanas, Shelby Fitch, Amber Ciravolo, Deborah Keenan, Naomi Cleghorn, Christine S. Lane, Thalassa Matthews, Curtis W. Marean

Geoscience Faculty Research

Approximately 74 thousand years ago (ka), the Toba caldera erupted in Sumatra. Since the magnitude of this eruption was first established, its effects on climate, environment and humans have been debated1. Here we describe the discovery of microscopic glass shards characteristic of the Youngest Toba Tuff—ashfall from the Toba eruption—in two archaeological sites on the south coast of South Africa, a region in which there is evidence for early human behavioural complexity. An independently derived dating model supports a date of approximately 74 ka for the sediments containing the Youngest Toba Tuff glass shards. By defining the input of shards …

Revisiting Polymorphism Of Molecular Crystals From The Melt, Alexander Shtukenberg, Qiang Zhu, Bart Kahr

Physics & Astronomy Faculty Research

No abstract provided.

Postaragonite Phases Of Caco3 At Lower Mantle Pressures, Dean Smith, Keith V. Lawler, Miguel Martinez-Canales, Austin W. Daykin, G. Alexander Smith, Christian Childs, Jesse S. Smith, Chris J. Pickard, Ashkan Salamat

Chemistry and Biochemistry Faculty Research

The stability, structure, and properties of carbonate minerals at lower mantle conditions have significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon hybridization, which has relevance for the storage of carbon within the deep mantle. Using high-pressure synchrotron x-ray diffraction in a diamond anvil cell coupled with direct laser heating of CaCO3 using a CO2 laser, we identify a crystalline phase of the material above 40 GPa—corresponding to a …

Visualization For Spatial Comprehension, Gabriel Judkins

UNLV Best Teaching Practices Expo

Mapping and understanding spatial data are fundamental necessities for geographers, yet challenging for many students (Rapp et al. 2007)

Elastic Geothermobarometry: Corrections For The Geometry Of The Host-Inclusion System, M. L. Mazzucchelli, Pamela Burnley, R. J. Angel, S. Morganti, M. C. Domeneghetti, F. Nestola, M. Alvaro

Geoscience Faculty Research

Elastic geothermobarometry on inclusions is a method to determine pressure-temperature conditions of mineral growth independent of chemical equilibrium. Because of the difference in their elastic properties, an inclusion completely entrapped inside a host mineral will develop a residual stress upon exhumation, from which one can back-calculate the entrapment pressure. Current elastic geobarometric models assume that both host and inclusion are elastically isotropic and have an ideal geometry (the inclusion is spherical and isolated at the center of an infinite host). These conditions do not commonly occur in natural rocks, and the consequences for inclusion pressures can only be quantified with …

Nevada Desert Dust With Heavy Metals Suppresses Igm Antibody Production, Deborah E. Keil, Brenda J. Buck, Dirk Goossens, Brett Mclaurin, Lacey Murphy, Mallory Leetham-Spencer, Yuanxin Teng, James E. Pollard, Russell Gerads, Jamie C. Dewitt

Geoscience Faculty Research

Systemic health effects from exposure to a complex natural dust containing heavy metals from the Nellis Dunes Recreation Area (NDRA) near Las Vegas, NV, were evaluated. Several toxicological parameters were examined following lung exposure to emissive dust from three geologic sediment types heavily used for recreational off-road activities: yellow sand very rich in arsenic (termed CBN 5); a shallow cover of loose dune sand overlying a gravelly subsoil bordering dune fields (termed CBN 6); and brown claystone and siltstone (termed CBN 7). Adult female B6C3F1 mice were exposed by oropharyngeal administration to these three types of geogenic dusts at 0.01–100 …

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. …

Miocene-Pliocene(?) Folds, Normal Faults And The Left-Lateral Buckhorn Fault With Regional Implications, Pahranagat Shear Zone, Nevada, Thomas Godfrey Price

UNLV Theses, Dissertations, Professional Papers, and Capstones

Strike-slip faults play an important role in the development and evolution of extensional regimes including in the intraplate extension in the Basin and Range province. The Basin and Range province is divided into the Northwestern, Northern, Central and Southern Basin and

Range subprovinces. The boundary zone between the Northern and Central subprovinces is marked by several left-lateral fault zones, including the Pahranagat Shear Zone (PSZ), Caliente-Enterprise Zone and Rock Valley Fault Zone. The PSZ has a close spatial and kinematic relationship with the left-lateral Caliente-Enterprise Zone, which lies to the NE, and a slightly more distal relationship to the left-lateral …

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 …

Phosphate Release: The Effect Of Prebiotic Organic Compounds On Dissolution Of Merrillite, Whitlockite, Chlorapatite, And Fluorapatite, Courtney Lea Bartlett

UNLV Theses, Dissertations, Professional Papers, and Capstones

Phosphate is an essential nutrient on Earth, used by life for ATP, DNA, RNA, and phospholipid membranes. Therefore, if life is or ever was present on Mars, phosphorus may have played an important role in determining the habitability of an environment. Phosphorus does not have a significant volatile phase; its release from minerals is consequently critical to phosphorus availability and prebiotic chemistry. Phosphate release from Mars-relevant minerals such as merrillite and chlorapatite has been previously found to differ significantly from phosphate release from fluorapatite, the dominant phosphate phase on Earth. However, the environments in which phosphate release would have been …

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 …

Behavioral Paleoecology Of Lower Cambrian Deposit Foragers: Reinterpreting Looping And Meandering Traces Using Optimal Foraging Theory And Quantitative Analysis, Zachary Andrew Jensen

UNLV Theses, Dissertations, Professional Papers, and Capstones

The early Cambrian was a period of transition during which the seafloor environment was changing from a microbial-mat-dominated environment to a bioturbation-dominated environment. The result was a patchy landscape of variable food resources for foraging burrowers to exploit. Looping trace fossils, such Psammichnites gigas and Taphrhelminthopsis nelsoni, appear in strata worldwide during this transitional period, and the ecological niche they filled is a subject of debate among ichnologists. The objectives of this study are (1) to determine the foraging strategies preserved by looping traces through the application of optimal foraging theory and quantitative analysis, and (2) use those results to …

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 …

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 …

Analyses Of Streamflow Change Patterns And Correlation Of These Changes With Sea-Surface Temperature Fluctuations, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents a comprehensive statistical analysis that determines the direction, rate, and interval of significant streamflow change patterns in the continental U.S. and correlates these changes with sea-surface temperature fluctuations. First, by using two non-parametric tests, namely, the Mann-Kendall trend test and the Pettitt’s test, the presence of long-term trends and abrupt shifts were determined at 10% significance level over continuously adjustable periods that stretched from 1903 to 2012. Modified versions of the tests were applied to account for the presence of persistence (autocorrelation) in data. Theil-Sen slope was determined to evaluate the rate of change across multiple temporal …

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 …

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 …

Effects Of Hydraulic Connections On Unsaturated Flow In Dual-Permeability Media, Jeevan Jayakody

UNLV Theses, Dissertations, Professional Papers, and Capstones

A geological medium that exhibits two distinct types of flow is known as dual-permeability medium. Unconsolidated deposits composed of coarse (> 2 mm diameter) clasts (gravel, talus, rockslide debris), engineered systems (heap leach piles, capillary barriers, rock fill), and mine/construction waste fall into this category. The large inter-clast pores that are characteristic of this type of media will drain at near zero matric potentials constraining flow to the interiors of porous clasts and/or the clast surfaces. In either case, water must pass through hydraulic bridges (porous contacts and/or pendular water) that form physical connections between neighboring clasts. Therefore, properties of …

Water Balance And Moisture Dynamics Of An Arid And Semi-Arid Soil: A Weighing Lysimeter And Field Study, Jeremy E. Koonce

UNLV Theses, Dissertations, Professional Papers, and Capstones

Semi-arid and arid environments are characterized by low precipitation and high evapotranspiration (ET), leaving little water available for discharge into surface water bodies and groundwater recharge. For these water-limited environments, understanding the relationships between precipitation, ET, and soil moisture is critical. These relationships not only affect water resources in these increasingly populated regions but are also necessary to predict the impact of climate change on semi-arid and arid ecosystems.

The overall goal of this dissertation was to shed light on the quantitative relationships between precipitation, evaporation, ET and soil moisture dynamics in an arid and a semi-arid environment. A three-step …

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 …

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 …

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 …

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 …