Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences Commons™

Open Access. Powered by Scholars. Published by Universities.®

Geochemistry

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 541 - 570 of 1549

Full-Text Articles in Earth Sciences

Fluid-Mobile Trace Element Variability Of Serpentinites And Entrained Crustal Rocks Across The Mariana Forearc System, Raymond M. Johnston Aug 2019

Fluid-Mobile Trace Element Variability Of Serpentinites And Entrained Crustal Rocks Across The Mariana Forearc System, Raymond M. Johnston

USF Tampa Graduate Theses and Dissertations

In the Mariana subduction system, active serpentinite mud volcanoes are associated with the subduction of the Pacific plate beneath the Philippine plate in a non-accretionary convergent plate margin. This location offers a unique opportunity to study the subduction zone interface with little crustal contamination. The systematics of fluid-mobile trace elements (FME) (As, Cs, Rb, Sb, Tl, Pb, and Sr) in erupted serpentinite muds and entrained serpentinized ultramafic and mafic clasts can place constraints on the release of slab-derived fluids from the downgoing plate, and ultimately the pressure/temperature (P/TC°) conditions at which these fluids are mobilized.

The samples analyzed in this …


Supporting Dataset For Chloride Source Delineation In An Urban-Agricultural Watershed, Deicing Agents Versus Agricultural Contributions, Eric Wade Peterson, Andrew Oberhelman Aug 2019

Supporting Dataset For Chloride Source Delineation In An Urban-Agricultural Watershed, Deicing Agents Versus Agricultural Contributions, Eric Wade Peterson, Andrew Oberhelman

Faculty Publications - Geography, Geology, and the Environment

Analyses (n = 535) of chloride (Cl-), bromide (Br-), nitrate as nitrogen (NO3-N), sodium (Na+), calcium (Ca2+), and potassium (K+) in stream water, tile-drain water, and groundwater were conducted in an urban-agricultural watershed (10% urban/impervious, 87% agriculture) to explore potential differences in the signature of Cl- originating from an urban source as compared to an agricultural source. Water samples were collected on a weekly interval from February 2018 to February 2019 at three station along the stream and from tile drains and wells. Nearly all surface water …


Insights Into The Evolution Of The Galápagos Archipelago And Its Mantle Source From Monogenetic Near-Island Seamounts, Darin M. Schwartz Aug 2019

Insights Into The Evolution Of The Galápagos Archipelago And Its Mantle Source From Monogenetic Near-Island Seamounts, Darin M. Schwartz

Boise State University Theses and Dissertations

Lavas erupted at ocean island volcanoes are classically used as probes of the deep Earth, with ultimate goals of discerning the compositional heterogeneity, structure and dynamics of the Earth’s mantle. However, sampling restricted to volcanic islands and large, submarine volcanic constructs alone likely results in limited spatial resolution of the mantle’s composition and structure, owing to homogenization in sub-island magma reservoirs. Further, islands provide poor temporal resolution given that their multigenetic construction can overprint any time progressive chemical variations and they subside with age making detailed sampling difficult. For my dissertation I investigate whether seamounts surrounding islands in the Galápagos …


Provenance And Maximum Depositional Age Analysis Of The Moenave Formation Using Detrital Zircon U-Pb Geochronology And Sandstone Petrography, Asher Rea Boudreaux Aug 2019

Provenance And Maximum Depositional Age Analysis Of The Moenave Formation Using Detrital Zircon U-Pb Geochronology And Sandstone Petrography, Asher Rea Boudreaux

Graduate Theses and Dissertations

In southwestern Utah and northeastern Arizona, Moenave Formation (latest Triassic(?)-Jurassic) is bracketed by well-studied Mesozoic units extensively sampled for detrital zircon geochronology and is poorly documented in regard to provenance, representing an important gap in knowledge. The Moenave Formation provides a unique opportunity to employ detrital zircon U-Pb geochronology and sandstone petrography relevant to completing the paleogeographic, evolutionary, and climatic story of the region. This study aims to characterize the sedimentary provenance of the Moenave Formation and to identify, or at least improve constraints on, the stratigraphic position of the Triassic-Jurassic boundary (TJB) and placement of the end-Triassic extinction (ETE), …


A Metasomatized Lithospheric Mantle Control On The Metallogenic Signature Of Post-Subduction Magmatism, David A. Holwell, Marco Fiorentini, Iain Mcdonald, Yongjun Lu, Andrea Giuliani, Daniel J. Smith, Manuel Keith, Marek Locmelis Aug 2019

A Metasomatized Lithospheric Mantle Control On The Metallogenic Signature Of Post-Subduction Magmatism, David A. Holwell, Marco Fiorentini, Iain Mcdonald, Yongjun Lu, Andrea Giuliani, Daniel J. Smith, Manuel Keith, Marek Locmelis

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Ore deposits are loci on Earth where energy and mass flux are greatly enhanced and focussed, acting as magnifying lenses into metal transport, fractionation and concentration mechanisms through the lithosphere. Here we show that the metallogenic architecture of the lithosphere is illuminated by the geochemical signatures of metasomatised mantle rocks and post-subduction magmatic-hydrothermal mineral systems. Our data reveal that anomalously gold and tellurium rich magmatic sulfides in mantle-derived magmas emplaced in the lower crust share a common metallogenic signature with upper crustal porphyry-epithermal ore systems. We propose that a trans-lithospheric continuum exists whereby post-subduction magmas transporting metal-rich sulfide cargoes play …


Biogeochemical Controls Of Surface Ocean Phosphate, Adam C. Martiny, Michael W. Lomas, Weiwei Fu, Philip W. Boyd, Yuh-Ling L. Chen, Gregory A. Cutter, Michael J. Ellwood, Ken Furuya, Fuminori Hasshihama, Jota Kanda, David M. Karl, Taketoshi Kodama, Qian P. Li, Jian Ma, Thierry Moutin, E. Malcolm S. Woodward, J. Keith Moore Aug 2019

Biogeochemical Controls Of Surface Ocean Phosphate, Adam C. Martiny, Michael W. Lomas, Weiwei Fu, Philip W. Boyd, Yuh-Ling L. Chen, Gregory A. Cutter, Michael J. Ellwood, Ken Furuya, Fuminori Hasshihama, Jota Kanda, David M. Karl, Taketoshi Kodama, Qian P. Li, Jian Ma, Thierry Moutin, E. Malcolm S. Woodward, J. Keith Moore

OES Faculty Publications

Surface ocean phosphate is commonly below the standard analytical detection limits, leading to an incomplete picture of the global variation and biogeochemical role of phosphate. A global compilation of phosphate measured using high-sensitivity methods revealed several previously unrecognized low-phosphate areas and clear regional differences. Both observational climatologies and Earth system models (ESMs) systematically overestimated surface phosphate. Furthermore, ESMs misrepresented the relationships between phosphate, phytoplankton biomass, and primary productivity. Atmospheric iron input and nitrogen fixation are known important controls on surface phosphate, but model simulations showed that differences in the iron-to-macronutrient ratio in the vertical nutrient supply and surface lateral transport …


The Paleozoic Sedimentary Rocks Of The Ouachita Mountains And Their Genetic Relationship To The Mississippi Valley-Type Mineralization In The Southern Ozark Region: Insights From Radiogenic Pb Isotopes And Trace Elements Studies, Christophe Wakamya Simbo Aug 2019

The Paleozoic Sedimentary Rocks Of The Ouachita Mountains And Their Genetic Relationship To The Mississippi Valley-Type Mineralization In The Southern Ozark Region: Insights From Radiogenic Pb Isotopes And Trace Elements Studies, Christophe Wakamya Simbo

Graduate Theses and Dissertations

Cluster of Pb and/or Zn deposits of the well-known Tri-State and Northern Arkansas Mississippi Valley Type (MVT) districts located north of the Arkoma basin and the Ouachita fold-thrust belt in north America are genetically connected to the Pennsylvanian-Permian Ouachita orogeny which triggered a South-North topographic gradient flow of basinal brines, leaching metal rich sediments en route. The objective of the research is twofold. First, to ascertain whether the organic-rich shales and sandstones from the study area provided metals during the mineralization event, which was coeval with the Ouachita orogeny. Second, to assess the depositional environment of the potential source rocks, …


Stable Isotope And Geochemical Characterization Of Nutrient Sources In The Big Creek Watershed Of Northwest Arkansas, Kelly Robin Sokolosky Aug 2019

Stable Isotope And Geochemical Characterization Of Nutrient Sources In The Big Creek Watershed Of Northwest Arkansas, Kelly Robin Sokolosky

Graduate Theses and Dissertations

The establishment of a concentrated animal-feeding operation (CAFO) in Newton County, Arkansas near Big Creek, a tributary of the Buffalo National River, has raised concern over potential degradation of water-quality in the watershed. In this study, isotopic tools were combined with standard geochemical approaches to characterize nutrient sources and dynamics in Big Creek. An isotopic and geochemical reference library of potential nutrient sources in the Big Creek watershed was established by direct sampling of representative potential sources, including septic-system effluent, poultry litter, swine and cattle manure, and CAFO waste lagoons. Representative nutrient sources and Big Creek stream samples were analyzed …


Assessing Bioavailability, Metal Fractionation, Magnetic Susceptibility, And Organic Matter Interactivity In Mine-Waste Contaminated Sediments In Turkey Creek, Joplin, Missouri, Zachary Joseph Collette Aug 2019

Assessing Bioavailability, Metal Fractionation, Magnetic Susceptibility, And Organic Matter Interactivity In Mine-Waste Contaminated Sediments In Turkey Creek, Joplin, Missouri, Zachary Joseph Collette

Graduate Theses/Dissertations

Joplin, Missouri, part of the Tri-State Mining District (TSMD), has a long history of mining that resulted in mine waste piles proximal to the mines throughout the area. A local lead smelter also resulted in smelter fallout in Joplin. Mine waste pile runoff and local smelter fallout resulted in contamination of sediments, soils, and waterways. In the 1990s, remediation of residential soils and play areas began after blood lead levels in children were much higher than the national average. Soon afterwards, the chat piles were removed and used for beneficial reuse purposes. In May of 2011, an EF5 tornado devastated …


Constraining The Oxygen Values Of The Late Cretaceous Western Interior Seaway Using Marine Bivalves, Camille H. Dwyer Jul 2019

Constraining The Oxygen Values Of The Late Cretaceous Western Interior Seaway Using Marine Bivalves, Camille H. Dwyer

Earth and Planetary Sciences ETDs

The Western Interior Seaway (WIS) remains an oceanographic enigma, including its circulation, similarity to the open ocean, and the fidelity of geochemical proxies to reconstruct paleoenvironments. Across the late Campanian and early Maastrichtian I test whether: 1) the WIS had unique δ18OVPDB compared to other marine settings, 2) increasing oceanographic restriction changed the stable isotope composition, and 3) biases, e.g., taxonomy or diagenesis, influenced stable isotope compositions. Results indicate distinct δ18OVPDB in the WIS compared to other marine settings. δ18OVPDB values were stable through time, suggesting insignificant oceanographic restriction and a …


Natural Salinization Of The Jemez River, New Mexico: An Insight From Trace Element Geochemistry, Jon K. Golla Jul 2019

Natural Salinization Of The Jemez River, New Mexico: An Insight From Trace Element Geochemistry, Jon K. Golla

Earth and Planetary Sciences ETDs

The Jemez River, a tributary of the Rio Grande in north-central New Mexico, receives thermal water input from the geofluids of the Valles Caldera, an active, high-temperature, liquid-dominated geothermal system. We focus on a ∼50-km portion of the northern Jemez River. This research extends previous decadal work (Crossey et al., in prep., 2013) on major chemistry in the river by characterizing the response of 16 trace elements to geochemical contributions from geothermal waters (McCauley, Spence, Soda Dam, and Jemez Springs springs and San Ysidro mineral waters), an area with copious hydrothermal degassing (Hummingbird), and two major tributaries (Rio San Antonio …


Identifying Characteristics Of Actionable Science For Drought Planning And Adaptation, Adam Wilke, Amanda Cravens Jul 2019

Identifying Characteristics Of Actionable Science For Drought Planning And Adaptation, Adam Wilke, Amanda Cravens

United States Geological Survey: Publications

Changing climate conditions can make water management planning and drought preparedness decisions more complicated than ever before. Federal and State natural resource managers can no longer rely solely on historical trends as a baseline and thus are in need of science that is relevant to their specific needs to inform important planning decisions. Questions remain, however, regarding the most effective and efficient methods for extending scientific knowledge and products into management and decision-making. This project analyzed two unique cases of water management to better understand how science can be translated into resource management actions and decision-making, focusing particularly on how …


A New Plumbing System Framework For Mantle Plume-Related Continental Large Igneous Provinces And Their Mafic-Ultramafic Intrusions, Richard E. Ernst, Dustin A. Liikane, Simon M. Jowitt, K. L. Buchan, J. A. Blanchard Jul 2019

A New Plumbing System Framework For Mantle Plume-Related Continental Large Igneous Provinces And Their Mafic-Ultramafic Intrusions, Richard E. Ernst, Dustin A. Liikane, Simon M. Jowitt, K. L. Buchan, J. A. Blanchard

Geoscience Faculty Research

The magmatic components of continental Large Igneous Provinces (LIPs) include flood basalts and their plumbing system of giant mafic dyke swarms (radiating, linear, and the recently discovered circumferential type), mafic sill provinces, a lower crustal magmatic underplate, mafic-ultramafic (M–UM) intrusions, associated silicic magmatism, and associated carbonatites and kimberlites. This paper proposes a new plumbing system framework for mantle plume-related continental LIPs that incorporates all of these components, and provides a context for addressing key thematic aspects such as tracking magma batches “upstream” and “downstream” and their geochemical evolution, assessing the setting of M-UM intrusions and their economic potential, interpreting deep …


Evaluating Fluid Fluxes From Deep-Sea Seepage Habitats, Leigha E. Peterson Jul 2019

Evaluating Fluid Fluxes From Deep-Sea Seepage Habitats, Leigha E. Peterson

Electronic Theses and Dissertations

The permanently dark deep-sea, located at oceanic water depths greater than 200 m, represents the largest potential habitat space on Earth. The physicochemical conditions of the planet’s largest biome are tightly coupled to the exchange of matter and energy from terrestrial and sea-floor end-members. In fact, global ocean and climate systems are significantly impacted by deep-sea processes. Seafloor vents and seeps appear to act as geologic exchange conduits, returning recycled materials to the hydrosphere to sustain another generation of life. Despite submarine seepage having control on global elemental cycling, it is estimated that less than 1% of the deep-sea has …


An Estimation Of Lower Tropospheric Mixing Derived From Inverse Modeling Of Boundary Layer Water Vapor Isotopologues On Graciosa Island, Azores, Jacquelyn M. Delp Jul 2019

An Estimation Of Lower Tropospheric Mixing Derived From Inverse Modeling Of Boundary Layer Water Vapor Isotopologues On Graciosa Island, Azores, Jacquelyn M. Delp

Earth and Planetary Sciences ETDs

Recent studies have shown water vapor isotopologues to be sensitive tracers of mixing processes that govern low-cloud feedback in climate models. In this study, we develop an inverse model (MBL Mix inverse model) that uses one year of isotope and humidity observations from Graciosa Island, Azores to estimate mixing for four seasons. We show the dry end-member of the model, the lower free troposphere (LFT), can be represented using Rayleigh fractionation. Isotope observations from Graciosa Island are compared to other field locations to discuss controls on isotopic variability other than mixing. Output from the MBL Mix inverse model shows the …


Stable Isotope Geochemistry Of Shelled Marine Invertebrates: Wide-Ranging Applications, Nasser M. Al-Qattan Jul 2019

Stable Isotope Geochemistry Of Shelled Marine Invertebrates: Wide-Ranging Applications, Nasser M. Al-Qattan

USF Tampa Graduate Theses and Dissertations

Mollusks grow by adding discrete growth layers throughout their lifetime (i.e., accretion). More specifically, most marine mollusks precipitate their shells in oxygen isotopic equilibrium with seawater or with a constant offset from equilibrium. The stable oxygen isotope values (δ18O) of their shells are determined by the temperature and δ18O values of the surrounding water during calcification without significant vital effects. In comparison, the stable carbon isotope values (δ13C) of their shells reflect those of the dissolved inorganic carbon (δ13C- DIC) and respired carbon dioxide. Therefore, variations in the oxygen and carbon isotope …


Limitations To Photosynthesis In Silver Bow And Blacktail Creeks, Isaiah Robertson Jul 2019

Limitations To Photosynthesis In Silver Bow And Blacktail Creeks, Isaiah Robertson

Graduate Theses & Non-Theses

Throughout Silver Bow Creek’s history, consideration of the photosynthetic communities that make heterotrophic life possible have often been overlooked since macroinvertebrates made up a majority of ecosystem health assessments. Silver Bow Creek has had minimal biological research outside of macroinvertebrate surveys, especially as it pertains to photosynthetic organisms. This study assessed the photosynthetic communities of Silver Bow Creek and their limitations by limiting available light and comparing uptake of nutrients during a 23-day incubation experiment conducted at four sites along the flow of Silver Bow Creek and Blacktail Creek. At each site, nine one-liter microcosms, filled with creek water and …


The Evolution Of The El Niño-Southern Oscillation And Tropical Pacific Climate Across The Last Deglaciation, Ryan Hunter Glaubke Jul 2019

The Evolution Of The El Niño-Southern Oscillation And Tropical Pacific Climate Across The Last Deglaciation, Ryan Hunter Glaubke

OES Theses and Dissertations

The El Niño – Southern Oscillation (ENSO) is the largest interannual component of Earth’s climate system, capable of exerting significant influence over global climate patterns that affect communities around the globe. Nevertheless, a comprehensive understanding of the ENSO system and its relationship to tropical Pacific climate dynamics remains unclear. Although new paleoceanographic proxies have shown promise in in their ability to constrain past ENSO change, little is known about how ENSO varied in response to millennial-scale climate events over the last 25,000 years. Here, I present new records of tropical Pacific mean state and ENSO variability over the last 25,000 …


Geothermometry Of H6 And L6 Chondrites And The Relationship Between Impact Processing And Retrograde Metamorphism, Michael Tyler Ream Jun 2019

Geothermometry Of H6 And L6 Chondrites And The Relationship Between Impact Processing And Retrograde Metamorphism, Michael Tyler Ream

Dissertations and Theses

Ordinary chondrites are the most common type of meteorite to fall to Earth and are composed of lithified primitive nebular materials which have experienced variable extents of thermal metamorphism and shock processing. They were subjected to radiogenic heating by incorporation of unstable short lived radionuclides such as 26Al in the early solar system.

The relationship between metamorphism and impact processing in ordinary chondrites is not fully understood. An unresolved issue in the study of ordinary chondrites is whether their original parent bodies were fragmented by impacts into rubble-pile bodies while they were still hot, or whether they retained their …


Rare Earth Geochemistry Of Apatitic Fossils From The Middle-Upper Ordovician Southern Margin Of Laurentia, Rafael Adrian Villanueva Jun 2019

Rare Earth Geochemistry Of Apatitic Fossils From The Middle-Upper Ordovician Southern Margin Of Laurentia, Rafael Adrian Villanueva

LSU Master's Theses

Widespread deposition of phosphate and a transition from tropical to cool water carbonates is seen throughout Middle-Upper Ordovician Nashville Dome area spanning the M4/M5 sequence boundary. Hypotheses explaining the onset of these lithologic changes have included the onset of glaciation, drawdown of CO2 related to the Guttenburg Isotope Carbon Excursion (GICE), and siliciclastic weathering, yet none of these studies have provided definitive evidence that shows any of these are the sole factor driving paleoenvironmental changes across the M4/M5 boundary. In order to test whether rapid subsidence along the southeastern margin of Laurentia may have caused an influx of phosphate …


Distribution And Origin Of Carbide In Ordinary Chondrites, Karla Rae Farley Jun 2019

Distribution And Origin Of Carbide In Ordinary Chondrites, Karla Rae Farley

Dissertations and Theses

To understand the occurrence and distribution of carbide minerals in ordinary chondrites, thirty meteorites were examined, twenty-eight ordinary chondrites and two iron meteorites. The occurrence of carbide, textures, and chemical compositions were examined in the 7 carbide-bearing meteorites. Two formation methods for carbide have been presented in previous research. These are aqueous alteration and shock heating, and they are examined for validity in this thesis. Additionally, one other formation method for carbide formation through impact and brecciation is put forth and examined. Textural differences between the carbide-magnetite assemblages (CMAs) observed by Krot et al., (1997) and those seen in this …


Williston Basin Water Treatment Technology Test Bed, University Of North Dakota. Energy And Environmental Research Center Jun 2019

Williston Basin Water Treatment Technology Test Bed, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet about Energy & Environmental Research Center plan to pilot-test technology to treat high-TDS (total dissolved solids) water. Includes a description of proposed water treatment technology and plan for the testing process. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]


Geochemical Analysis Of The Chinchín Formation In Southern Ecuador, Katherine Ludwig May 2019

Geochemical Analysis Of The Chinchín Formation In Southern Ecuador, Katherine Ludwig

Celebration of Learning

The subduction of the Nazca Plate under the South American Plate has led to the uplift of the majority of the Andes Mountains, but in Ecuador, the Nazca Plate subducts underneath the North Andes Plate, which then collides with the South American Plate. This tectonic setting has formed two parallel mountain chains as well as a complex series of basins between them. However, the formations that make up these basins are poorly understood. This study focuses on the Chinchín Formation, an ~3.5 km thick, volcanic formation that serves as the bedrock of the Quingeo Basin in southern Ecuador. This study …


Petrology And Geochemistry Of The Bearwallow Mountain Andesite, Mogollon-Datil Volcanic Field, New Mexico, Conor Lee O'Dowd May 2019

Petrology And Geochemistry Of The Bearwallow Mountain Andesite, Mogollon-Datil Volcanic Field, New Mexico, Conor Lee O'Dowd

Graduate Theses/Dissertations

The Mogollon-Datil volcanic field (MDVF), located in southern New Mexico, is the result of episodic volcanism and the transition between arc and rift magmatism. The MDVF has been the focus of several mapping, stratigraphic, petrologic, geochronological, and geochemical studies to understand the complete volcanic and tectonic history. However, the majority of previous studies lack geochemical analyses on intermediate composition volcanic rocks, giving more attention to the large-volume ignimbrites and rhyolite flows as well as the minor basalt flows that occurred between 36 and 20 Ma. I present new whole-rock major- and trace-element analyses and petrographic textures on one of the …


An In-Situ Study Of The Aqueous Speciation Of Uranium (Vi) Under Hydrothermal Conditions, Diwash Dhakal May 2019

An In-Situ Study Of The Aqueous Speciation Of Uranium (Vi) Under Hydrothermal Conditions, Diwash Dhakal

Graduate Theses/Dissertations

Rigorous study of the speciation distribution of uranyl-chloride bearing solutions under hydrothermal conditions is important to understand the transport mechanism of uranium underground, which is of uttermost interest to parties studying the geological uranium deposits and those studying the possibilities of geological repositories for spent nuclear waste. I report an in-situ Raman spectroscopic study of the speciation distribution of aqueous uranyl-chloride complexes upto 500°C conducted using a HDAC as the high PT spectroscopic cell. The samples studied contained the species UO22+, UO2Cl+, UO2Cl20 and UO2Cl3- …


Pressure-Induced Phase Transition In 1,3,5-Triamino-2,4,6-Trinitrobenzene (Tatb), Brad A. Steele, Samantha M. Clarke, Matthew P. Kroonblawd, I-Feng W. Kuo, Philip F. Pagoria, Sergey N. Tkachev, Jesse S. Smith, Sorin Bastea, Laurence E. Fried, Joseph M. Zaug, Elissaios Stavrou, Oliver Tschauner May 2019

Pressure-Induced Phase Transition In 1,3,5-Triamino-2,4,6-Trinitrobenzene (Tatb), Brad A. Steele, Samantha M. Clarke, Matthew P. Kroonblawd, I-Feng W. Kuo, Philip F. Pagoria, Sergey N. Tkachev, Jesse S. Smith, Sorin Bastea, Laurence E. Fried, Joseph M. Zaug, Elissaios Stavrou, Oliver Tschauner

Geoscience Faculty Research

Determining the unreacted equation of state of 1,3, 5-triamino-2,4,6-trinitrobenzene (TATB) is challenging because it exhibits low crystal symmetry and low X-ray scattering strength. Here, we present the first high-pressure single-crystal X-ray diffraction (SXD) study of this material. Our SXD results reveal a previously unknown transition to a monoclinic phase above 4 GPa. No abrupt change of the volume occurs but the compressibility changes. Concomitant first principles evolutionary crystal structure prediction USPEX calculations confirm this transition and show that it involves a pressure-induced in-plane shift of the layers of TATB molecules with respect to the ambient-pressure phase.


Morphological And Mineralogical Evidence For Ancient Bat Presence In Cova Des Pas De Vallgornera (Llucmajor, Mallorca, Western Mediterranean), Antoni Merino, Joan J. Fornós, Antoni Mulet, Joaquín Ginés May 2019

Morphological And Mineralogical Evidence For Ancient Bat Presence In Cova Des Pas De Vallgornera (Llucmajor, Mallorca, Western Mediterranean), Antoni Merino, Joan J. Fornós, Antoni Mulet, Joaquín Ginés

International Journal of Speleology

Cova des Pas de Vallgornera is a unique karst cave located at the Llucmajor coastal platform that stands out not only because of its length, more than 78 km, but also for its particular morphological suite, richness and variety of speleothems and mineral infillings. Although the mineralogy of speleothems and minerals related to hypogene morphologies has been studied and described, the existence of minerals derived from guano deposits was still poorly investigated. The cave hosted bat colonies until the collapse of its natural entrances, circa 2.4 My ago, since then until its discovery in 1968, the cave remained sealed. These …


Lead Contamination Of Soils In An Abandoned Rifle Range, Augusta County, Virginia, Logan Mahoney May 2019

Lead Contamination Of Soils In An Abandoned Rifle Range, Augusta County, Virginia, Logan Mahoney

Senior Honors Projects, 2010-2019

Presence of high concentrations of Lead within the soil and water could lead to various health related impacts on humans and wildlife. Exposure to Lead short termly or long termly could lead to many detrimental impacts due to Lead poisoning. The overall concentration of Lead in a soil can be measured using an Inductively Coupled Plasma Mass Spectrometry (ICPMS) under laboratory conditions. The present study investigates the Lead concentration of contaminated abandoned riffle range located in Augusta County, Virginia. Soil samples were obtained using soil augurs from three locations randomly based on the severity of contamination. Location three, which was …


Giant Beaver Palaeoecology Inferred From Stable Isotopes, Tessa Plint, Fred J. Longstaffe, Grant Zazula May 2019

Giant Beaver Palaeoecology Inferred From Stable Isotopes, Tessa Plint, Fred J. Longstaffe, Grant Zazula

Earth Sciences Publications

This is a multi-individual (n = 11), stable carbon and nitrogen isotope study of bone collagen (δ13Ccol and δ15Ncol) from the giant beaver (genus Castoroides). The now-extinct giant beaver was once one of the most widespread Pleistocene megafauna in North America. We confirm that Castoroides consumed a diet of predominantly submerged aquatic macrophytes. These dietary preferences rendered the giant beaver highly dependent on wetland habitat for survival. Castoroides’ δ13Ccol and δ15Ncol do not support the hypothesis that the giant beaver consumed trees or woody …


Petrogenesis Of Off-Axis Lavas Erupted Along The 8˚20’ N Seamount Chain, East Pacific Rise, Molly Kassandra Anderson May 2019

Petrogenesis Of Off-Axis Lavas Erupted Along The 8˚20’ N Seamount Chain, East Pacific Rise, Molly Kassandra Anderson

Boise State University Theses and Dissertations

Lavas erupted at off-axis seamounts provide a window into mantle heterogeneity and melting systematics that are not easily observed on-axis at fast spreading mid-ocean ridges (MORs). This is because axial melts are efficiently mixed and homogenized within shallow axial magma chambers prior to eruption. To understand the deeper magmatic processes contributing to oceanic crustal formation, we examine the compositions of lavas erupted along a chain of off-axis seamounts, adjacent to the East Pacific Rise (EPR). Essential questions include: (1) What is the range of compositional variability erupted off-axis and how does that compare to lavas erupted on-axis? (2) Is there …