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2019

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Articles 151 - 180 of 408

Full-Text Articles in Geology

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 …


Structural Control Of Mesic Vegetation Communities Within The Owl And Bear Creek Watersheds, Fort Hood Military Installation, Texas, Melinda S. Faulkner, Matthew Mcbroom, Kenneth W. Farrish, Kevin Stafford Jun 2019

Structural Control Of Mesic Vegetation Communities Within The Owl And Bear Creek Watersheds, Fort Hood Military Installation, Texas, Melinda S. Faulkner, Matthew Mcbroom, Kenneth W. Farrish, Kevin Stafford

Faculty Publications

The Fort Hood Military Installation is a karst landscape, dominated by Lower Cretaceous carbonates of the Trinity and Fredericksburg groups. The study area is the northeastern peninsula known as the Owl Mountain Province, utilized by the U.S. Army for troop maneuvers and training. The geomorphic evolution of the province has been controlled by the structural development of incised canyons in the Owl and Bear creek watersheds, following the deformational trend of the Balcones/Ouachita fault system and the transverse Belton High-Central Texas Reef Trend. These trends control cave development in the subsurface, karst manifestations at the surface, joints in outcrop, stream …


Investigation Of Pervasive Clay Layers And Their Effect On Groundwater Flow Using Electrical Resistivity Tomography In The San Antonio Groundwater Basin, James M. Carlson Jun 2019

Investigation Of Pervasive Clay Layers And Their Effect On Groundwater Flow Using Electrical Resistivity Tomography In The San Antonio Groundwater Basin, James M. Carlson

Natural Resources Management and Environmental Sciences

The United States Geological Survey is developing an integrated hydrologic model of the San Antonio Creek Groundwater Basin to better understand and simulate the integrated surface water and groundwater system. An abrupt 60 meter offset in groundwater depth over a distance of less than one kilometer is observed in well readings within the Cañada De Las Flores region of the groundwater basin. Abrupt changes in groundwater levels are often explained by the presence of a fault in the subsurface vertically offsetting sedimentary units. However, observations of the structural geology of this region indicates that faulting is unlikely and suggests an …


Mineralogy And Chemistry Of Rare Earth Elements In Alkaline Ultramafic Rocks And Fluorite In The Western Kentucky Fluorspar District, Warren H. Anderson Jun 2019

Mineralogy And Chemistry Of Rare Earth Elements In Alkaline Ultramafic Rocks And Fluorite In The Western Kentucky Fluorspar District, Warren H. Anderson

Report of Investigations--KGS

Rare earth elements, or REE, are used in modern society in televisions, computers, cellphones, military equipment, and smart weapons systems. These metals are also used by the medical industry in magnetic resonance imaging and in medical products.

The igneous rocks in the Western Kentucky Fluorspar District of the New Madrid Rift System are considered alkaline ultramafic rocks that are slightly enriched in REE. These rocks are rare and only occur in several hundred locations in the world. They have a complex history of emplacement, fractionation, metasomatism, and alteration, and are overprinted with Mississippi Valley-type mineralization. They are classified as lamprophyres …


Petrogenesis Of The Eagle East Gabbro In Marquette County, Mi, Usa, Kevin Rupp Jun 2019

Petrogenesis Of The Eagle East Gabbro In Marquette County, Mi, Usa, Kevin Rupp

Masters Theses

The Eagle East gabbroic intrusion in Michigan’s Upper Peninsula, is a subvertical pluglike intrusion found near the base of the Eagle East Ni-Cu-PGE deposit. U-Pb baddeleyite dating of the gabbro yields an age of 1103.4 ± 1.2 Ma, suggesting formation during the early stages of the Midcontinent Rift System (MRS). Drill core observations show that the intrusion cross-cuts the eastern most portion of the Eagle East ultramafic conduit. The internal portion of the intrusion is made up of two main rock types, gabbro and gabbro norite, which consist of plagioclase (50-60%), clinopyroxene (15-25%), orthopyroxene (0-15%), olivine (0-10%), and are generally …


Basinward Trends In Fluvial Architecture, Connectivity, And Reservoir Characterization Of The Trail Member, Ericson Sandstone, Mesaverde Group In Wyoming, Utah, And Colorado, Usa, Chelsea Anne Jolley Jun 2019

Basinward Trends In Fluvial Architecture, Connectivity, And Reservoir Characterization Of The Trail Member, Ericson Sandstone, Mesaverde Group In Wyoming, Utah, And Colorado, Usa, Chelsea Anne Jolley

Theses and Dissertations

The Late Cretaceous Trail Member of the Ericson Sandstone represents a regionally extensive fluvial system that transported sediments from the Sevier fold and thrust belt and Uinta Mountain uplift to the Western Interior Seaway. The Trail Member is a petroleum reservoir target that has unpredictable production rates due to the unknown behavior and connectivity of channel sandstones. The abundant outcrop, wellbore, and core data available allows for a comprehensive analysis of how the fluvial architecture, connectivity, and reservoir quality change along 65 km of depositional dip. Observations made at Flaming Gorge and Clay Basin (most landward field locations) suggest a …


Ages Of Prehistoric Earthquakes On The Banning Strand Of The San Andreas Fault, Near North Palm Springs, California, Bryan Castillo Jun 2019

Ages Of Prehistoric Earthquakes On The Banning Strand Of The San Andreas Fault, Near North Palm Springs, California, Bryan Castillo

Electronic Theses, Projects, and Dissertations

We studied a paleoseismic trench that was excavated across the Banning strand of the San Andreas Fault by Petra Geosciences (33.9172°, -116.538°). The trench exposed a ~40 m wide fault zone in interbedded alluvial sand gravel, silt and clay deposits. We present the first paleoseismic record for the Banning strand of the southern San Andreas Fault. The most recent event occurred sometime between 730 and 950 cal BP, potentially coincident with rupture of the San Gorgonio Pass thrust. We interpret that five earthquakes have occurred since 3.3-2.5 ka and eight earthquakes have likely occurred since 7.1-5.7 ka. It is possible …


Genetic Sequencing For Measuring Biodiversity In Recent And Ancient Marine Sediments, Lauren Judge May 2019

Genetic Sequencing For Measuring Biodiversity In Recent And Ancient Marine Sediments, Lauren Judge

Celebration of Learning

Taxonomic biodiversity, measured by counting the number of species present in a given area, is the most common method of capturing ecosystem biodiversity in recent and ancient environments. While this method is widely accepted, it is limited by poor preservation and identification of many individuals, making it impossible to include every species within an ecosystem and resulting in the loss of some diversity information. To address this issue, we measured the genetic biodiversity (in which species are determined based on sequencing of their DNA) of shallow marine ecosystems by extracting and sequencing the 18S ribosomal gene from bulk carbonate sediment …


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 …


Understanding The Bioavailability Of Pyrethroids In The Aquatic Environment Using Chemical Approaches, Zhijiang Lu, Jay Gan, Xinyi Cui, Laura Delgado-Moreno, Kunde Lin May 2019

Understanding The Bioavailability Of Pyrethroids In The Aquatic Environment Using Chemical Approaches, Zhijiang Lu, Jay Gan, Xinyi Cui, Laura Delgado-Moreno, Kunde Lin

Environmental Science and Geology Faculty Research Publications

Pyrethroids are a class of commonly used insecticides and are ubiquitous in the aquatic environment in various regions. Aquatic toxicity of pyrethroids was often overestimated when using conventional bulk chemical concentrations because of their strong hydrophobicity. Over the last two decades, bioavailability has been recognized and applied to refine the assessment of ecotoxicological effects of pyrethroids. This review focuses on recent advances in the bioavailability of pyrethroids, specifically in the aquatic environment. We summarize the development of passive sampling and Tenax extraction methods for assessing the bioavailability of pyrethroids. Factors affecting the bioavailability of pyrethroids, including physicochemical properties of pyrethroids, …


Middle Miocene To Holocene History Of The Delacroix Island Fault System, Jarrett Leigh Levesh May 2019

Middle Miocene To Holocene History Of The Delacroix Island Fault System, Jarrett Leigh Levesh

LSU New Orleans Theses and Dissertations

An in-depth field study of the Delacroix Island producing field illustrates the evolution of the east-trending Delacroix Island Fault during the last 13 My. Well log correlations and 3-D seismic interpretation of 22 subsurface bio-stratigraphic horizons across the fault reveal variable stratigraphic thicknesses and displacement. Wells, with well log curve data as shallow as 31 m (100 ft) below the surface, were used to calculate interval thicknesses, expansion indices, sediment accumulation rates, burial history and magnitudes of displacement. Through these analyses, a correlation was found between the positioning of ancient Miocene depocenters over Delacroix Island and a period of increased …


Seamless Lidar Surveys Reveal Rates And Patterns Of Subsidence In The Mississippi River Delta, Celeste E. Woock May 2019

Seamless Lidar Surveys Reveal Rates And Patterns Of Subsidence In The Mississippi River Delta, Celeste E. Woock

LSU New Orleans Theses and Dissertations

Light Detection and Ranging (Lidar) data are used to report the temporal and spatial patterns of subsidence as well as the potential contributors to subsidence within the Barataria and Terrebonne Bays. In recent decades, subsidence in southeast Louisiana has become a topic of substantial and growing concern to the scientific community, the local residents, and all those invested in the region. Lidar data were acquired from the United States Geological Survey (USGS) and the LSU Center for Geoinformatics. The data has been manipulated to map the differenced Lidar, complete an instantaneous slope analysis, and determine the thickness of the Holocene …


Tidal And Spatial Variability Of Flow Speed And Seismicity Near The Grounding Zone Of Beardmore Glacier, Antarctica, Jade Cooley, J. Paul Winberry, Michelle Koutnik, Howard Conway May 2019

Tidal And Spatial Variability Of Flow Speed And Seismicity Near The Grounding Zone Of Beardmore Glacier, Antarctica, Jade Cooley, J. Paul Winberry, Michelle Koutnik, Howard Conway

All Faculty Scholarship for the College of the Sciences

GPS measurements of tidal modulation of ice flow and seismicity within the grounding zone of Beardmore Glacier show that tidally induced fluctuations of horizontal flow are largest near the grounding line and decrease downstream. Seismic activity is continuous, but peaks occur on falling and rising tides. Beamforming methods reveal that most seismic events originate from two distinct locations, one on the grid-north side of the grounding zone, and one on the grid-south side. The broad pattern of deformation generated as Beardmore Glacier merges with the Ross Ice Shelf results in net extension along the grid-north side of the grounding zone …


Geomorphic Response To Catastrophic Flooding In A Karst Mountain Stream System, Brighton-Blue Hole Watershed, Southwest Jamaica, Sarah M. Letarte May 2019

Geomorphic Response To Catastrophic Flooding In A Karst Mountain Stream System, Brighton-Blue Hole Watershed, Southwest Jamaica, Sarah M. Letarte

Graduate Theses/Dissertations

The geomorphic effects of flooding are poorly understood in the karst, mountain watersheds along the southwest coast of Jamaica. This study describes the flow path and geomorphic response of an extreme flood event in the Brighton-Blue Hole watershed (BBHW) (6.8 km2) near Belmont, Westmoreland, Jamaica. A tropical depression classified as a >100-year rainfall event produced 32 inches of rain in a 24 hour period in Westmoreland on June 12, 1979. For this study, geomorphic indicators of flood disturbance in BBHW were assessed in 2017-18, finding that channel system responded to the flood with channel incision, debris flows, and …


Detecting Ocean Microplastics With Remote Sensing In The Near-Infrared: A Feasibility Study, Jandlyn Bentley May 2019

Detecting Ocean Microplastics With Remote Sensing In The Near-Infrared: A Feasibility Study, Jandlyn Bentley

Honors Program Theses and Projects

Since plastic began entering the oceans in the 1950s, trends have shown that this pollution has been and will continue to increase in the future. The only method to estimate the abundance and distribution of ocean plastic pollution is by computer-generated models using data from in-situ plankton net tows, which are costly, time consuming, and cover a relatively small scale. This project investigates the potential of detecting ocean microplastics with satellite remote sensing based on theoretically elevated near-infrared (NIR) reflectance. Emphasis was placed on the Great Pacific Garbage Patch in the North Pacific Ocean, notorious for its extremely high concentration …


Floodwater Impact On Galveston Bay Phytoplankton Taxonomy, Pigment Composition And Photo-Physiological State Following Hurricane Harvey From Field And Ocean Color (Sentinel-3a Olci) Observations, Eurico D'Sa May 2019

Floodwater Impact On Galveston Bay Phytoplankton Taxonomy, Pigment Composition And Photo-Physiological State Following Hurricane Harvey From Field And Ocean Color (Sentinel-3a Olci) Observations, Eurico D'Sa

Faculty Publications

Phytoplankton taxonomy, pigment composition and photo-physiological state were studied in Galveston Bay (GB), Texas (USA), following the extreme flooding associated with Hurricane Harvey (25-29 August 2017) using field and satellite ocean color observations. The percentage of chlorophyll a (Chl a) in different phytoplankton groups was determined from a semi-analytical IOP (inherent optical property) inversion algorithm. The IOP inversion algorithm revealed the dominance of freshwater species (diatom, cyanobacteria and green algae) in the bay following the hurricane passage (29 September 2017) under low salinity conditions associated with the discharge of floodwaters into GB. Two months after the hurricane (29-30 October 2017), …


Glacial Meltwater Modeling To Simulate Streamflow And Lake Levels In Taylor Valley, Antarctica, Julian M. Cross, Andrew G. Fountain May 2019

Glacial Meltwater Modeling To Simulate Streamflow And Lake Levels In Taylor Valley, Antarctica, Julian M. Cross, Andrew G. Fountain

Student Research Symposium

The McMurdo Dry Valleys (MDV) are the largest ice-free region (4,500 km2) in Antarctica. The MDV are a polar desert with an average annual temperature of -18˚C and minimal precipitation, < 50 mm w.e. a-1. In Taylor Valley (77°35’ S, 163°00’ E), a closed-basin, perennially ice-covered lakes occupy the valley floor. Ephemeral streams transfer glacier meltwater for ~10 weeks each summer. Glacial meltwater accounts for nearly the total inflow to these streams and lakes, groundwater is essentially non-existent. A microbially-dominated ecosystem in Taylor Valley depends on glacier runoff and thus is highly sensitive to changes to the hydroclimatic regime. A model …


Cluster Chondrite Accretion Temperatures Determined With Electron Backscatter Diffraction, Secana Goudy, Alexander Ruzicka May 2019

Cluster Chondrite Accretion Temperatures Determined With Electron Backscatter Diffraction, Secana Goudy, Alexander Ruzicka

Student Research Symposium

We studied ordinary chondrites with cluster chondrite lithologies using electron backscatter diffraction to measure the temperatures of their olivine grains during deformation. Samples analyzed with the technique are shock classified as S1 and are type 3, so the deformation analyzed is inferred to represent the temperatures of the chondrules during accretional deformation. It was found that the studied samples are of a mixture of chondrules at mostly hot temperatures (>850°C) and some at cold.


Multi-Proxy Characterization Of Acex Subunit 1/5 (The “Zebra” Interval) To Better Understand Sediment Deposition At This Critical Age Boundary And Paleoceanographic Transition, Victoria Hojnacki May 2019

Multi-Proxy Characterization Of Acex Subunit 1/5 (The “Zebra” Interval) To Better Understand Sediment Deposition At This Critical Age Boundary And Paleoceanographic Transition, Victoria Hojnacki

Senior Honors Projects, 2010-2019

Sediment cores recovered from the Lomonosov Ridge on IODP Expedition 302, the Arctic Coring Expedition (ACEX), provided the first major insights into long-term Cenozoic history of climate and ocean conditions in the central Arctic. However, the ACEX record is hampered by a major hiatus or severely condensed interval (depending on age-model interpretations) at 198.7 mcd separating the middle Eocene and Miocene records. Lithologic subunit 1/5 lies above this depth horizon, and is informally called the “zebra interval” because of distinctive stripes - black and gray tilted and cross-banded silty-clay layers, up to 3 cm thick that characterize the lower ~2.5 …


Soil Capability Assessment For Expanding Irrigated Agriculture In The Irwin Focus Area And Surrounding Lands, Edward (Ted) Arnold Griffin, Angela Stuart-Street, Peter Tille May 2019

Soil Capability Assessment For Expanding Irrigated Agriculture In The Irwin Focus Area And Surrounding Lands, Edward (Ted) Arnold Griffin, Angela Stuart-Street, Peter Tille

Resource management technical reports

The Midlands groundwater and land assessment is a $4.7 million Water for Food project using Royalties for Regions funding. It is seeking to confirm groundwater availability in focus areas that may form precincts of 2000–3000ha suitable for intensive irrigated horticulture. Irwin is one of these.

The Department of Water identified the Irwin focus area for investigation for irrigated agriculture potential. It covers almost 7000ha to the east of Dongara in the Mid West region of Western Australia.

This report provides the land assessment for the Irwin area. We expanded the investigation to include land outside of the focus area because …


Assessing Paleoenvironmental And Geomorphic Variability In Relationship To Paleoindian Site Burial; Centennial Valley, Montana, Hillary A. Jones May 2019

Assessing Paleoenvironmental And Geomorphic Variability In Relationship To Paleoindian Site Burial; Centennial Valley, Montana, Hillary A. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wave action along the shores of Lima Reservoir in Centennial Valley, Montana is actively eroding the southern margins of three neighboring Paleoindian sites. Despite ostensible similarity among the sites, major site formation differences are apparent in exposed sediments. Shoreline cutbank exposures one-to-five meters high connect the sites and reveal a complicated geomorphic history. Although each site contains artifact evidence of terminal Pleistocene-early Holocene occupations, Paleoindian components at these three localities occur in very different contexts: one is buried, while the other two are apparent surface scatters. This raise the question of why sites of the same age are in both …


Micro- To Macro-Scale Structural And Lithological Architecture Of Basal Nonconformities: Implications For Fluid Flow And Injection Induced Seismicity, Garth Hesseltine May 2019

Micro- To Macro-Scale Structural And Lithological Architecture Of Basal Nonconformities: Implications For Fluid Flow And Injection Induced Seismicity, Garth Hesseltine

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rising incidents of earthquakes caused by human activity in the United States, known as induced earthquakes, is a growing concern. Induced earthquakes may occur when fluid and/or wastewater is injected several kilometers beneath the Earth’s surface into sedimentary rocks. Fluids and pressures can migrate from the sedimentary rocks, which are typically friendlier to fluid flow, into underlying less friendlier crystalline rocks along fluid pathways weakening and possibly reactivating preexisting faults. Understanding potential fluid pathways and/or barriers from the sedimentary rocks to crystalline rocks is crucial. I investigate the structure, composition, and heterogeneity of rocks near the contact between the sedimentary …


Facies And Diagenesis Analyses Of The Fort Terrett Formation Of The Lower Cretaceous Edwards Group, Near Junction, Texas, Richard Alden Urwin Jr. May 2019

Facies And Diagenesis Analyses Of The Fort Terrett Formation Of The Lower Cretaceous Edwards Group, Near Junction, Texas, Richard Alden Urwin Jr.

Electronic Theses and Dissertations

The Fort Terrett Formation was deposited on the western edge of the Comanche Shelf in central Texas. The predominate lithology of the Fort Terrett Formation is limestone which caps the hills that surround Junction, Texas. Deposition of the Fort Terrett Formation occurred within shallow, quiet waters during the Lower Cretaceous. Rose (1974) developed a general stratigraphic correlation and lithostratigraphic framework for the Cretaceous Shelf and established a regional correlation. Four stratigraphic divisions have been recognized in the Fort Terrett Formation. These are: a basal nodular unit, a burrowed unit, a dolomitic unit, and the Kirschberg evaporites. Wilkerson (2018) provided the …


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 …


A Bayesian Framework For Estimating Seismic Wave Arrival Time, Hua Zhong May 2019

A Bayesian Framework For Estimating Seismic Wave Arrival Time, Hua Zhong

Graduate Theses and Dissertations

Because earthquakes have a large impact on human society, statistical methods for better studying earthquakes are required. One characteristic of earthquakes is the arrival time of seismic waves at a seismic signal sensor. Once we can estimate the earthquake arrival time accurately, the earthquake location can be triangulated, and assistance can be sent to that area correctly. This study presents a Bayesian framework to predict the arrival time of seismic waves with associated uncertainty. We use a change point framework to model the different conditions before and after the seismic wave arrives. To evaluate the performance of the model, we …


Incorporating Recent Geochemical And Isotopic Constraints In Age Dating The Waters Of Hot Springs National Park, Arkansas, Kristina Marie Raley May 2019

Incorporating Recent Geochemical And Isotopic Constraints In Age Dating The Waters Of Hot Springs National Park, Arkansas, Kristina Marie Raley

Graduate Theses and Dissertations

Mean water age for spring discharge in Hot Springs National Park was calculated as approximately 4,400 years by Bedinger et al (1978) using carbon-14. Their analysis indicated that the water was a mixture of a small portion of cold water that was less than twenty years old with a preponderance of hot water. However, this result includes some error due to Bedinger et al. using general isotopic values for soil dissolved inorganic carbon and mineral carbon instead of obtaining actual values from the study area. A more accurate age calculation for the springs has been made possible by additional geological …


Mountain-Block Recharge To The Cache Valley Principal Aquifer And Geochemical Controls On Groundwater Movement In Alpine Karst, Skyler J. Sorsby May 2019

Mountain-Block Recharge To The Cache Valley Principal Aquifer And Geochemical Controls On Groundwater Movement In Alpine Karst, Skyler J. Sorsby

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Groundwater is documented to flow through solution-widened fractures and bedding planes in limestone and dolostone units in low-relief topography. This enhancement, or karstification, is much harder to study in alpine environments like the Bear River Range of northern Utah. This is problematic, due to the fact that the Bear River Range karst aquifer system supplies the City of Logan with a large quantity of water at Dewitt Spring. Furthermore, the karst aquifer sustains the Logan River for much of the year, and may allow groundwater to flow directly in the subsurface to the Cache Valley principal aquifer system.

Flow measurements …


Petrogenesis Of The El Rechuelos Rhyolite, Jemez Mountains Volcanic Field, New Mexico, Usa, Kelsy Jo Konkright May 2019

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 …


Stratigraphy And Depositional Characterization Of The Moorefield Shale (Middle-Late Mississippian) In Its Type Area, Northeastern Arkansas (Eastern Arkoma Basin), Griffin Warner May 2019

Stratigraphy And Depositional Characterization Of The Moorefield Shale (Middle-Late Mississippian) In Its Type Area, Northeastern Arkansas (Eastern Arkoma Basin), Griffin Warner

Graduate Theses and Dissertations

The Moorefield Shale represents the Meramecian Series in the Eastern Arkoma Basin in northern Arkansas. Lying on the margin of the Mississippi Embayment and Reelfoot Rift, sequence stratigraphic interpretations have labelled the Moorefield Shale a lowstand wedge succeeding the Early Mississippian (Osagean) Boone Limestone conformably and overlain conformably by the Hindsville Limestone/Batesville Sandstone. The unit contains a basal brown-black limestone and succeeding brown-black phosphatic shale. The Moorefield Shale was deposited along the broad, stable cratonic platform on the southern flank of Laurasia, before it’s collision with Gondwanaland to form the supercontinent Pangea at the end of the Paleozoic. During this …


Geochemical Analysis Of Mississippian Cherts And Devonian-Mississippian Novaculites, Southern Midcontinent Region, Julie Mary Cains May 2019

Geochemical Analysis Of Mississippian Cherts And Devonian-Mississippian Novaculites, Southern Midcontinent Region, Julie Mary Cains

Graduate Theses and Dissertations

This study uses trace elements and radiogenic isotopes (Pb, Sr, and Nd) to investigate the origin and mode of formation for the siliceous deposits in the Lower Mississippian Boone Formation and the Devonian-Mississippian Arkansas Novaculite in the southern midcontinent. Mississippi Valley-type Pb-Zn ore deposits in the Tri-State District and the Northern Arkansas District were deposited by hydrothermal fluids, and highly radiogenic Pb isotope ratios suggest a genetic relationship between the Boone Formation chert (206Pb/204Pb ~ 21.59, 207Pb/204Pb ~ 15.87, 208Pb/204Pb ~ 40.10) and the MVT ores. Due to the very low concentration of Pb in the Boone chert (~2 ppm) …