Geology Commons^™

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 …

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 …

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 …

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 …

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 …

Pacific Southwest United States Holocene Droughts And Pluvials Inferred From Sediment Δ18o (Calcite) And Grain Size Data (Lake Elsinore, California), Matthew E.C. Kirby, William Paul Patterson, Matthew Lachniet, James A. Noblet, Michael A. Anderson, Kevin Nichols, Judith Avila

Geoscience Faculty Research

Records of past climate can inform us on the natural range and mechanisms of climate change. In the arid Pacific southwestern United States (PSW), which includes southern California, there exist a variety of Holocene records that can be used to infer past winter conditions (moisture and/or temperature). Holocene records of summer climate, however, are rare from the PSW. In the future, climate changes due to anthropogenic forcing are expected to increase the severity of drought in the already water stressed PSW. Hot droughts are of considerable concern as summer temperatures rise. As a result, understanding how summer conditions changed in …

Speleothem Paleoclimatology For The Caribbean, Central America, And North America, Jessica L. Oster, Sophie F. Warken, Natasha Sekhon, Monica M. Arienzo, Matthew Lachniet

Geoscience Faculty Research

Speleothem oxygen isotope records from the Caribbean, Central, and North America reveal climatic controls that include orbital variation, deglacial forcing related to ocean circulation and ice sheet retreat, and the influence of local and remote sea surface temperature variations. Here, we review these records and the global climate teleconnections they suggest following the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database. We find that low-latitude records generally reflect changes in precipitation, whereas higher latitude records are sensitive to temperature and moisture source variability. Tropical records suggest precipitation variability is forced by orbital precession and North Atlantic Ocean …