Physical Sciences and Mathematics Commons^™

Examination Of Maskelynite Through Static Recompression And Dynamic Compression, Justin James Reppart

UNLV Theses, Dissertations, Professional Papers, and Capstones

This is an experimental study that aims to clarify the possible formation mechanisms of maskelynite. Maskelynite is a diaplectic glass, that forms during shock compression of feldspar far below the melting point, and without fusion. Maskelynite also paramorphises precursor feldspar grains. Maskelynite is an important probe of shock-pressures at terrestrial impact sites and in many meteorites. Two mechanisms of formation of maskelynite are examined here: 1) maskelynite is result of a pressure-induced amorphization of feldspar compressed beyond its mechanical stability where the formation of thermodynamically stable phases is kinetically inhibited [1, 2]. 2) Feldspar transforms upon dynamic compression into a …

Utility Of Bench Scale Sand Tank Experiments At Assessing Permeable Reactive Barrier Design, Brandon Meier

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this work was to evaluate the utility of bench scale sand tank experiments at assessing permeable reactive barrier (PRB) design. Our criteria for meeting this goal was that differences between PRB designs could be identified solely by measuring concentration in outflow from the sand tank models. For our PRB designs (funnel-and-gate, staggered wells, and parallel bars), numerical simulations clearly showed that PRB design had a quantifiable effect on outflow concentration, provided that the solute reacted with the PRB materials. Conversely, use of a conservative (non-reactive) solute did not allow us to discern between PRB design alternatives. Employing …

Moisture Dynamics Of A Near-Surface Desert Soil, Yuan Luo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Desert soils cover about one third of the Earth’s land surface. Despite their large extent, however, our understanding of desert soil hydraulic processes and properties is still rather limited. In particularly with respect to the near-surface (top centimeters) of the soil profile, which play a critical role for infiltration, redistribution and evapotranspiration of rainwater, the limiting resource for life in desert environments, but also hosts most of the biologic activity and controls runoff, erosion as well as the emission of dust (Nannipieri et al.,2003; Bradford et al.,1987). Additionally, deserts are ideal locations for electricity generation with solar energy using large-scale …

Application Of Semi-Hydrophobic Layers To Decrease Bare Soil Evaporation, Jesse Lee Barnes

UNLV Theses, Dissertations, Professional Papers, and Capstones

Evaporative water loss from bare agricultural soils is a primary area of water conservation research. Mulching is the commonly utilized method to decrease evaporative water loss. The most commonly utilized mulch is nonbiodegradable polyethylene sheeting because it tends to decrease evaporative water loss and increase crop yields more than environmentally friendly mulches. This study aimed to test the utility of sand coated with polymerized soybean oil (i.e., hydrophobic sand) as a treatment to reduce bare soil evaporation and an alternative to current practices. Evaporation rates were measured in laboratory soil columns containing both treated and untreated soils. Treatment parameters were …

Petrogenesis Of Unusual Occurrence Of Amphibole Asbestos In Mohave County, Arizona And Clark County, Nevada, Tomoyo Austin

UNLV Theses, Dissertations, Professional Papers, and Capstones

The term “asbestos” applies to six types of fibrous amphiboles or chrysotile with specific morphologies that are commercially mined and processed. Inhaling asbestos fibers is known to cause many negative health effects, including mesothelioma, several different cancers, various respiratory diseases and non-respiratory diseases, and fatalities. The recent years, several cases of non-occupational exposure to asbestos fibers raised an awareness of environmental exposure to naturally occurring asbestos (NOA) which refers to asbestiform minerals that fall out of the regulatory definition of asbestos.

There are two sources of NOA in the area, Wilson Ridge pluton, AZ, and Boulder City pluton, NV which …

Assessing Minimal-Input Restoration Strategies For Desert Soil And Vegetation Restoration, Audrey Jean Rader

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Mojave and Sonoran Deserts have been negatively impacted by anthropogenic disturbances. Considering that these ecosystems may recover on millennial timescales, research has shown that restoration techniques can be fairly successful in initiating long-term recovery processes in these sensitive environments. However, uncertainty remains as to which techniques are effective in different circumstances, such as in different climates or across different soil properties, and which techniques may best avoid unintended consequences, such as facilitating non-native plants. To reduce fugitive dust as a human health hazard, increase soil stability, and enhance wildlife habitat, further work is necessary to develop restoration techniques for …

Early Contractional History Of The Funeral Mountains And Its Influence On The Formation Of The Funeral Mountains Metamorphic Core Complex, Death Valley, Ca, Taylor Douglas Craig

UNLV Theses, Dissertations, Professional Papers, and Capstones

Zones of localized crustal thickening in orogenic belts commonly host low-angle normal faults, which have been controversial since their recognition. The metamorphic core complexes of the Sevier hinterland are localized within a belt that is attributed with the highest degrees of crustal thickening during Sevier orogenesis. This association of deep-rooted detachment faulting and early contractional deformation indicates an important link between the two processes, however repeated tectonic episodes often overprint and obscure the earlier fabrics, making this link difficult to study. The Funeral Mountains metamorphic core complex, located in Death Valley, CA, has a complex history of protracted SE-contraction and …

Assessing Simulated Transmissivity In Numerical Flow Models Of Complex Hydrogeology, Afan Tarar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurately extracting a meaningful transmissivity, a target value within one order of magnitude of field estimates, in numerical models poses a significant challenge when modeling complex groundwater systems. Aquifer transmissivity is directly proportional to the aquifer thickness and the estimated aquifer hydraulic conductivity. In complex geologic conditions (especially in fractured systems) with multiple heterogeneous and anisotropic hydrogeologic units, transmissivity can vary over several orders of magnitude.

To extract a meaningful value of transmissivity from a numerical model, a simple five-layer MODFLOW model was constructed. Each layer in the model was assigned a fixed hydraulic conductivity and thickness. The model simulates …

Petrogenesis Of The El Rechuelos Rhyolite, Jemez Mountains Volcanic Field, New Mexico, Usa, Kelsy Jo Konkright

UNLV Theses, Dissertations, Professional Papers, and Capstones

The El Rechuelos Rhyolite represents volcanic activity preceding the multiple caldera collapse events of the Jemez Mountains volcanic field (JMVF) in northern New Mexico. This study focuses on seven rhyolitic units clustered north of the Valles caldera. These units have been studied in order to interpret their relationships to one another and the eruptive history of the JMVF. Additionally, this study adds to the research on the relationships between effusive and explosive rhyolitic volcanism, and understanding how caldera-forming eruptions develop from silicic systems.

Limited previous research includes K/Ar dates and a few inconsistent 40Ar/39Ar dates, in addition to whole rock …

Multi-Resolution Spatio-Temporal Change Analyses Of Hydro-Climatological Variables In Association With Large-Scale Oceanic-Atmospheric Climate Signals, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary objective of the work presented in this dissertation was to evaluate the change patterns, i.e., a gradual change known as the trend, and an abrupt change known as the shift, of multiple hydro-climatological variables, namely, streamflow, snow water equivalent (SWE), temperature, precipitation, and potential evapotranspiration (PET), in association with the large-scale oceanic-atmospheric climate signals. Moreover, both observed datasets and modeled simulations were used to evaluate such change patterns to assess the efficacy of the modeled datasets in emulating the observed trends and shifts under the influence of uncertainties and inconsistencies. A secondary objective of this study was to …