Physical Sciences and Mathematics Commons^™

Chronicling Magma Transit Beneath Hawaiian Volcanoes: Every Isotope A Word, Every Crystal A Story, Jonathan Pinko

UNLV Theses, Dissertations, Professional Papers, and Capstones

At many oceanic volcanoes, such as Hawaii, mantle-derived magmas migrate to crustal level magma chambers, where they accumulate before eruption. Understanding the magma chamber residence times, or the time gaps between the arrivals of new magmas and eruptions, is important in volcanic hazard mitigation. Here I apply iron and magnesium isotope effects in olivines to constrain these times at Hawaiian volcanoes. Combined with published data, I present bulk ?56Fe (-1.706 to 0.489) and ?26Mg (-0.400 to 0.356) in 108 Hawaiian olivines erupted from the pre-shield, shield, and post-shield stages. The Hawaiian olivine ?56Fe and ?26Mg represent the largest Fe-Mg isotope …

Water Source Partitioning For Shrubland Transpiration In A Mixed Phreatophytic Plant Community, Amanda Jean Wagner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater in the basins of east central Nevada (Great Basin Desert, NV) has been permitted for export to southern Nevada. These basins are also vulnerable to changes in climate that could lead to declining recharge. Any decline in groundwater levels no matter the driving force could significantly impact phreatophytes (deep rooted shrubs), which utilize water from both the vadose zone and the capillary fringe to meet plant water needs, to support growth, and for overall health. A reduction in groundwater due to these forces could have a significant impact on the decoupling of phreatophytes from what is normally a reliable …

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 …

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 …