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Articles 511 - 540 of 1194
Full-Text Articles in Earth Sciences
Evaluation Of Potential Translocation Sites For An Imperiled Cyprinid, The Hornyhead Chub, Brian T. Hickerson, Annika W. Walters
Evaluation Of Potential Translocation Sites For An Imperiled Cyprinid, The Hornyhead Chub, Brian T. Hickerson, Annika W. Walters
United States Geological Survey: Staff Publications
Translocation of isolated species into suitable habitats may help to secure vulnerable, geographically limited species. Due to the decline of Wyoming Hornyhead Chub Nocomis biguttatus, conservation actions, such as the translocation of populations within the plausible historical range, are being considered to improve population redundancy and resiliency to disturbance events. Translocation of Wyoming Hornyhead Chub must be rigorously evaluated because a hatchery stock does not exist, so all fish used in translocations will come from the wild population. We present an approach to identify the best available translocation sites prior to translocation efforts taking place. We evaluated fish community composition …
Formation Of Evolved Rocks At Gale Crater By Crystal Fractionation And Implications For Mars Crustal Composition, Arya Udry, Esteban Gazel, Harry Y. Mcsween Jr.
Formation Of Evolved Rocks At Gale Crater By Crystal Fractionation And Implications For Mars Crustal Composition, Arya Udry, Esteban Gazel, Harry Y. Mcsween Jr.
Geoscience Faculty Research
The recent discovery of some ancient evolved rocks in Gale crater by the Curiosity rover has prompted the hypothesis that continental crust formed in early Martian history. Here we present petrological modeling that attempts to explain this lithological diversity by magma fractionation. Using the thermodynamical software MELTS, we model fractional crystallization of different Martian starting compositions that might generate felsic igneous compositions like those analyzed at Gale crater using different variables, such as pressure, oxygen fugacities, and water content. We show that similar chemical and mineralogical compositions observed in Gale crater felsic rocks can readily be obtained through different degrees …
A Novel Multiproxy Approach To Reconstructing Sea Surface Temperature In The Southwestern Gulf Of Mexico, Marissa Anne Vara
A Novel Multiproxy Approach To Reconstructing Sea Surface Temperature In The Southwestern Gulf Of Mexico, Marissa Anne Vara
LSU Master's Theses
Coral Sr/Ca is a widely-used proxy for sea surface temperature (SST); however, discrepancies in the coral Sr/Ca-SST relationship among colonies of the same species makes uncertainty in absolute temperature reconstructions larger than the climate signal yet climate variability studies are possible. Furthermore, the riverine input of terrestrial carbonate weathering products to the coastal waters can disrupt the coral Sr/Ca-SST signal by changing local seawater chemistry. This study evaluates the fidelity and reproducibly of coral SST proxies (Sr/Ca, Li/Ca, Mg/Li, Sr-U, Mg/Ca, and U/Ca) and a riverine-upwelling proxy (Ba/Ca) in four Orbicella faveolata colonies in two reefs offshore from Veracruz, Mexico …
Macrobenthic Infaunal Communities Associated With Deep‐Sea Hydrocarbon Seeps In The Northern Gulf Of Mexico, Travis W. Washburn, Amanda W. J. Demopoulos, Paul A. Montagna
Macrobenthic Infaunal Communities Associated With Deep‐Sea Hydrocarbon Seeps In The Northern Gulf Of Mexico, Travis W. Washburn, Amanda W. J. Demopoulos, Paul A. Montagna
United States Geological Survey: Staff Publications
There are thousands of seeps in the deep ocean worldwide; however, many questions remain about their contributions to global biodiversity and the surrounding deep‐sea environment. In addition to being globally distributed, seeps provide several benefits to humans such as unique habitats, organisms with novel genes, and carbon regulation. The purpose of this study is to determine whether there are unique seep macrobenthic assemblages, by comparing seep and nonseep environments, different seep habitats, and seeps at different depths and locations. Infaunal community composition, diversity, and abundance were examined between seep and nonseep background environments and among three seep habitats (i.e., microbial …
Placing The Common Era In A Holocene Context: Millennial To Centennial Patterns And Trends In The Hydroclimate Of North America Over The Past 2000 Years, Bryan N. Shuman, Cody Routson, Nicholas Mckay, Sherilyn C. Fritz, Darrell Kaufman, Matthew E. Kirby, Connor Nolan, Gregory T. Pederson, Jeannine-Marie St-Jacques
Placing The Common Era In A Holocene Context: Millennial To Centennial Patterns And Trends In The Hydroclimate Of North America Over The Past 2000 Years, Bryan N. Shuman, Cody Routson, Nicholas Mckay, Sherilyn C. Fritz, Darrell Kaufman, Matthew E. Kirby, Connor Nolan, Gregory T. Pederson, Jeannine-Marie St-Jacques
Department of Earth and Atmospheric Sciences: Faculty Publications
A synthesis of 93 hydrologic records from across North and Central America, and adjacent tropical and Arctic islands, reveals centennial to millennial trends in the regional hydroclimates of the Common Era (CE; past 2000 years). The hydrological records derive from materials stored in lakes, bogs, caves, and ice from extant glaciers, which have the continuity through time to preserve low-frequency ( > 100 year) climate signals that may extend deeper into the Holocene. The most common pattern, represented in 46 (49 %) of the records, indicates that the centuries before 1000 CE were drier than the centuries since that time. Principal …
Introduction To A Resources Special Issue On Criticality Of The Rare Earth Elements: Current And Future Sources And Recycling, Simon M. Jowitt
Introduction To A Resources Special Issue On Criticality Of The Rare Earth Elements: Current And Future Sources And Recycling, Simon M. Jowitt
Geoscience Faculty Research
The rare earth elements (REE) are vital to modern technologies and society and are amongst the most important of the critical elements. This special issue of Resources examines a number of facets of these critical elements, current and future sources of the REE, the mineralogy of the REE, and the economics of the REE sector. These papers not only provide insights into a wide variety of aspects of the REE, but also highlight the number of different areas of research that need to be undertaken to ensure sustainable and secure supplies of these critical metals into the future.
Optimizing Uav Surveys For Coastal Morphodynamics: Estimation Of Spatial Uncertainty As A Function Of Flight Acquisition And Post-Processing Factors, Mark Lundine
Celebration of Learning
Recent developments in unmanned aerial vehicles (UAVs) and photogrammetry software enable the rapid collection of aerial photography and video over study areas of varying sizes, thereby providing ease of use and accessibility for studies of coastal geomorphology. However, there remains uncertainty over UAV survey techniques, with disagreement on specific flight patterns, flight altitudes, photograph amounts, ground control point (GCP) amounts, GCP spacing schemes, drone models, and which SfM software to use, amongst other study-specific parameters.
A controlled field test (of 1.2 hectares) was performed to determine SfM’s sensitivity to the following flight parameters: altitude (60 m, 80 m, 120 m), …
Landscape Analysis Of Soil Methane Flux Across Complex Terrain, Kendra E. Kaiser, Brian L. Mcglynn, John E. Dore
Landscape Analysis Of Soil Methane Flux Across Complex Terrain, Kendra E. Kaiser, Brian L. Mcglynn, John E. Dore
Geosciences Faculty Publications and Presentations
Relationships between methane (CH4) fluxes and environmental conditions have been extensively explored in saturated soils, while research has been less prevalent in aerated soils because of the relatively small magnitudes of CH4 fluxes that occur in dry soils. Our study builds on previous carbon cycle research at Tenderfoot Creek Experimental Forest, Montana, to identify how environmental conditions reflected by topographic metrics can be leveraged to estimate watershed scale CH4 fluxes from point scale measurements. Here, we measured soil CH4 concentrations and fluxes across a range of landscape positions (7 riparian, 25 upland), utilizing topographic and …
Micropaleontological Record Of A Preserved, Late Pleistocene Bald Cypress Forest On The Northern Gulf Of Mexico Inner Shelf, Jonathan Thien Truong
Micropaleontological Record Of A Preserved, Late Pleistocene Bald Cypress Forest On The Northern Gulf Of Mexico Inner Shelf, Jonathan Thien Truong
LSU Master's Theses
A cluster of previously buried Taxodium distichum stumps are exposed and preserved in growth position at the bottom of a trough on the inner Gulf of Mexico (GOM) continental shelf in 18 m water depth and 13 km offshore Orange Beach, AL. Radiocarbon ages from wood and optically stimulated luminescence (OSL) dating of sediments suggest a Marine Isotope Stage (MIS) 3 age, or older. This study builds on the previous work of Gonzalez (2018) and Obeclz (2017). Five biofacies were identified in vibracore collected in 2015 and 2016: 1) the Holocene Mississippi-Alabama-Florida (MAFLA) sand sheet, 2) a Holocene interbedded sand …
Spatial And Temporal Analysis Of Island Morphology In Lower Pool 18 Of The Mississippi River, Marissa C. Iverson
Spatial And Temporal Analysis Of Island Morphology In Lower Pool 18 Of The Mississippi River, Marissa C. Iverson
Celebration of Learning
The Upper Mississippi River System has a significant trend in island loss due to river engineering structures. However, Lower Pool 18 is observed as a counterexample to the island loss pattern with its island development near Lock and Dam 18 during the past 80 years. This research is modeled after a study done in Lower Pool 6 of the Upper Mississippi River where an island development was found to contradict the island loss prevalence. The Lower Pool 18 research’s goal is to map, describe, and explain spatial patterns of islands growth, persistence and loss. Historical maps and aerial photographs of …
Use Of Floodscape Mapping To Assess Changes In Inundation Frequency Of The Upper Mississippi River, Jeffrey L. Swanson
Use Of Floodscape Mapping To Assess Changes In Inundation Frequency Of The Upper Mississippi River, Jeffrey L. Swanson
Celebration of Learning
As an alternative to probability-based maps, DeJager (and others) reconceptualized floodplain mapping using the notion of “floodscapes” (DeJager et al., 2015). A floodscape map is developed using daily stage data and high-resolution topography to create maps that depict the average number of days of inundation (per year or growing season). Floodscape maps reveal intricate and continuous patterns of high-frequency flows that are critically important to floodplain ecological functioning. DeJager found significant correlations between floodscape inundation and riparian vegetation patterns but single floodscape maps only provide snapshots in time. This current research develops and utilizes multiple floodscape maps to quantify changes …
A Quantitative Analysis Of The Effects Of Urbanization, Mesophication And Prescribed Burns On Oak Woodlands In The Chicago Metropolitan Area, Chad Populorum
A Quantitative Analysis Of The Effects Of Urbanization, Mesophication And Prescribed Burns On Oak Woodlands In The Chicago Metropolitan Area, Chad Populorum
Celebration of Learning
Urban expansion has had devastating impacts on forest ecosystems, especially within the past century. Human attempts to dominate nature have diminished natural disturbance regimes, which have maintained the biodiversity and historic composition of these ecosystems. Fires have been a prominent force in maintaining the structure of oak, hickory and other heliophytic (sun loving and fire-adapted) forest systems. Human induced fire suppression has led to mesophication across North America. Mesophication is the transition from drier conditions with open canopies to wetter conditions with closed canopies. These new conditions decrease the survival rates of these important species and begin to favor mesophytic …
Steering Operational Synergies In Terrestrial Observation Networks: Opportunity For Advancing Earth System Dynamics Modelling, Roland Baatz, Pamela L. Sullivan, Li Li, Samantha R. Weintraub, Henry W. Loescher, Michael Mirtl, Peter M. Groffman, Diana H. Wall, Michael Young, Tim White, Hang Wen, Steffen Zacharias, Ingolf Kühn, Jianwu Tang, Jérôme Gaillardet, Isabelle Braud, Alejandro N. Flores, Praveen Kumar, Henry Lin, Teamrat Ghezzehei, Julia Jones, Henry L. Gholz, Harry Vereecken, Kris Van Looy
Steering Operational Synergies In Terrestrial Observation Networks: Opportunity For Advancing Earth System Dynamics Modelling, Roland Baatz, Pamela L. Sullivan, Li Li, Samantha R. Weintraub, Henry W. Loescher, Michael Mirtl, Peter M. Groffman, Diana H. Wall, Michael Young, Tim White, Hang Wen, Steffen Zacharias, Ingolf Kühn, Jianwu Tang, Jérôme Gaillardet, Isabelle Braud, Alejandro N. Flores, Praveen Kumar, Henry Lin, Teamrat Ghezzehei, Julia Jones, Henry L. Gholz, Harry Vereecken, Kris Van Looy
Geosciences Faculty Publications and Presentations
Advancing our understanding of Earth system dynamics (ESD) depends on the development of models and other analytical tools that apply physical, biological, and chemical data. This ambition to increase understanding and develop models of ESD based on site observations was the stimulus for creating the networks of Long-Term Ecological Research (LTER), Critical Zone Observatories (CZOs), and others. We organized a survey, the results of which identified pressing gaps in data availability from these networks, in particular for the future development and evaluation of models that represent ESD processes, and provide insights for improvement in both data collection and model integration. …
Results Of Test-Hole Drilling For Observation Well Planning In The Lower Loup Natural Resources District, Spring 2017, Douglas R. Hallum P.G., Sue Olafsen Lackey, Steven S. Sibray
Results Of Test-Hole Drilling For Observation Well Planning In The Lower Loup Natural Resources District, Spring 2017, Douglas R. Hallum P.G., Sue Olafsen Lackey, Steven S. Sibray
Conservation and Survey Division: Faculty and Staff Publications
The High Plains Aquifer underlies much of Nebraska. It is the primary source of groundwater within the Lower Loup Natural Resources District (LLNRD) of central Nebraska. Water derived from the aquifer is an important natural resource for the area and supplies water for recreation, wildlife and agriculture, as well as domestic, municipal, and industrial uses. Falling spring water levels measured in existing observation and irrigation wells have raised concerns about possible changes in water availability, groundwater-surface water relationships and water quality in the area, prompting the LLNRD to propose test holes and the collection of additional groundwater data in the …
Organochlorine Chemical Residues In Northern Cardinal (Cardinalis Cardinalis) Eggs From Greater Washington, Dc Usa, Christopher J. Schmitt, Kathy E. Echols, Paul H. Peterman, Carl E. Orazio, K. Christiana Grim, Shirlee Tan, Nora E. Diggs, Peter P. Marra
Organochlorine Chemical Residues In Northern Cardinal (Cardinalis Cardinalis) Eggs From Greater Washington, Dc Usa, Christopher J. Schmitt, Kathy E. Echols, Paul H. Peterman, Carl E. Orazio, K. Christiana Grim, Shirlee Tan, Nora E. Diggs, Peter P. Marra
United States Geological Survey: Staff Publications
Northern Cardinal eggs from six neighborhoods near Washington DC were analyzed for organochlorine pesticides and PCBs. All compounds were detected more frequently and at higher concentrations in more heavily urbanized neighborhoods. DDT (mostly as p,pʹ-DDE) was detected in all neighborhoods. p,pʹ-DDT was typically 0.5‒16 ng/g (ww) in most suburban neighborhoods but was not detected (< 0.1 ng/g) in more rural areas; however, p,pʹ-DDT was 127‒1130 ng/g in eggs from two suburban Maryland nests and comprised 65.7% of total p,pʹ-DDT isomers in the most contaminated sample, indicating recent exposure to un-weathered DDT. Total chlordane (sum of 5 compounds) was 2‒70 ng/g; concentrations were greatest in older suburban neighborhoods. Total PCB (sum of detected congeners) was < 5‒21 ng/g. Congener patterns were similar in all neighborhoods and resembled those typical of weathered mixtures. Results indicate that wildlife remains exposed to low concentrations of legacy contaminants in suburban neighborhoods and that cardinal eggs can be used to monitor local- ized contamination.
Smap Soil Moisture Change As An Indicator Of Drought Conditions, Rajasekaran Eswar, Narendra N. Das, Calvin Christian Poulsen, Ali Behrangi, John Swigart, Mark D. Svoboda, Dara Entekhabi, Simon Yueh, Bradley Doorn, Jared Entin
Smap Soil Moisture Change As An Indicator Of Drought Conditions, Rajasekaran Eswar, Narendra N. Das, Calvin Christian Poulsen, Ali Behrangi, John Swigart, Mark D. Svoboda, Dara Entekhabi, Simon Yueh, Bradley Doorn, Jared Entin
National Drought Mitigation Center: Faculty Publications
Soil moisture is considered a key variable in drought analysis. The soil moisture dynamics given by the change in soil moisture between two time periods can provide information on the intensification or improvement of drought conditions. The aim of this work is to analyze how the soil moisture dynamics respond to changes in drought conditions over multiple time intervals. The change in soil moisture estimated from the Soil Moisture Active Passive (SMAP) satellite observations was compared with the United States Drought Monitor (USDM) and the Standardized Precipitation Index (SPI) over the contiguous United States (CONUS). The results indicated that the …
Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender
Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender
Student Theses 2015-Present
This paper aims to shed light on the dissonance caused by the superimposition of Dominant Human Systems on Natural Systems. I highlight the synthetic nature of Dominant Human Systems as egoic and linguistic phenomenon manufactured by a mere portion of the human population, which renders them inherently oppressive unto peoples and landscapes whose wisdom were barred from the design process. In pursuing a radical pragmatic approach to mending the simultaneous oppression and destruction of the human being and the earth, I highlight the necessity of minimizing entropic chaos caused by excess energy expenditure, an essential feature of systems that aim …
Cretaceous Dinosaurs And The World They Lived In: A New Species Of Ornithischian Dinosaur From The Early Cretaceous (Aptian) Of Texas, Reconstruction Of The Brain Endocast And Inner Ear Of Malawisaurus Dixeyi, And Reconstruction Of The Paleoclimate And Paleoenvironment Of Cretaceous Terrestrial Formations In Texas And Oklahoma Using Pedogenic Minerals, Kate Andrzejewski
Earth Sciences Theses and Dissertations
Material from over thirty individuals of a new ornithopod was recovered from the Proctor Lake locality in the Twin Mountains Formation (Aptian) of north-central Texas. This material includes various ontogenetic stages, providing insight into the growth patterns of this species. The new ornithopod is recovered basal to Iguanodontia, but more derived than Hypsilophodon foxii. The presence and morphology of 4 premaxillary teeth along with a combination of both basal and derived characters distinguish this taxon from all other ornithopods.
A braincase of the Cretaceous titanosaurian sauropod Malawisaurus dixeyi was CT scanned and a 3D rendering of the endocast and inner …
Determining Principal Stress Orientations And Magnitudes In The Fort Worth Basin, Texas, Louis Quinones
Determining Principal Stress Orientations And Magnitudes In The Fort Worth Basin, Texas, Louis Quinones
Earth Sciences Theses and Dissertations
Since 2008, the Fort Worth Basin in northern Texas has experienced over 30 M3.0+ earthquakes, including one M4.0. Earthquakes have primarily occurred on Precambrian basement faults and within the overlying Ellenburger limestone unit, which is the primary wastewater disposal formation used in the basin. The most productive earthquake sequences (Azle, Irving- Dallas, and Venus) have been recorded using local seismic networks containing a mix of SMU broadband, IRIS short period, and USGS NetQuakes stations and by regional seismic networks operated under the Advanced National Seismic System and the Texas Seismic Network (TexNet).
Using the data recorded by the local seismic …
Characterization Of Ground Deformation Associated With Shallow Groundwater Processes Using Satellite Radar Interferometry, Xie Hu
Earth Sciences Theses and Dissertations
Shallow groundwater processes maylead to ground deformation and even geohazards. With the features of day-and-night accessibility and large-scale coverage, time-series interferometric synthetic aperture radar (InSAR) has proven a useful tool for mapping the deformation over various landscapes at cm to mm level with weekly to monthly updates. However, it has limitations such as, decorrelation,atmospheric artifacts, topographic errors, andunwrapping errors, in particular for the hilly, vegetated, and complicated deformation patterns. In this dissertation, I focus on characterizing the ground deformation over landslides, aquifer systems, and mine tailings impoundment, using the designed advanced time-series InSAR strategy, as well as theinterdisciplinary knowledge of …
The Role Of Basin Configuration And Allogenic Controls On The Stratigraphic Evolution Of River Mouth Bars, Joshua Flathers
The Role Of Basin Configuration And Allogenic Controls On The Stratigraphic Evolution Of River Mouth Bars, Joshua Flathers
LSU New Orleans Theses and Dissertations
Deltas are important coastal systems throughout the world. River mouth bars are key landforms in the development of deltas, are characterized by sediment deposition, and have high potential for sediment preservation. Scientists and professionals seek to understand the discrete response of mouth bars to the various controls governing their evolution. This study utilizes the numerical modelling software Delft3D to provide additional evidence supporting the morphological and stratigraphic responses resulting from variations in basin configurations and allogenic controls (fluvial discharge, tides, basin width). Mud content within the bar increased analogous to an increase in the tidal modulation, while a decrease in …
No One Likes An Ash Hole: Advocating For A Management Scheme That Prioritizes Beneficial Utilization Of Coal Ash In The United States And Georgia Through Domestic And International Comparisons, Ethan Keith Norris
Georgia Journal of International & Comparative Law
No abstract provided.
Provenance And Paleogeography Of The 25-17 Ma Rainbow Gardens Formation: Evidence For Tectonic Activity At Ca. 19 Ma And Internal Drainage Rather Than Throughgoing Paleorivers On The Southwestern Colorado Plateau, Melissa A. Lamb, L. Sue Beard, Malia Dragos, Andrew D. Hanson, Thomas A. Hickson, Mark Sitton, Paul J. Umhoefer, Karl E. Karlstrom, Nelia Dunbar, William Mcintosh
Provenance And Paleogeography Of The 25-17 Ma Rainbow Gardens Formation: Evidence For Tectonic Activity At Ca. 19 Ma And Internal Drainage Rather Than Throughgoing Paleorivers On The Southwestern Colorado Plateau, Melissa A. Lamb, L. Sue Beard, Malia Dragos, Andrew D. Hanson, Thomas A. Hickson, Mark Sitton, Paul J. Umhoefer, Karl E. Karlstrom, Nelia Dunbar, William Mcintosh
Geoscience Faculty Research
The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25–17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24–19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and …
Reconstruction Of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis Of Subglacial Lake And Ice Stream Sediments, Patrick Baudoin
Reconstruction Of Antarctic Cenozoic Paleoenvironments Through Palynological Analysis Of Subglacial Lake And Ice Stream Sediments, Patrick Baudoin
LSU Master's Theses
The West Antarctic Ice Sheet (WAIS), with a large portion being grounded below sea level, is historically known for its instability. Timing and evaluating the magnitude of WAIS advance and retreat is essential to improve our understanding of control mechanisms. The scarcity of accessible subglacial geology in areas such as the Siple Coast in West Antarctica limits our understanding and ability to gauge WAIS response to environmental changes. To evaluate the ice-sheet history around the Siple Coast, i.e., when it was last covered by vegetation, access to sediment immediately below the ice-sheet is essential. In the absence of large-scale drilling, …
The Relationship Between Urban Tree Lai And Urban Heat, Amanda Sheepherd, Dr. Ryan Jensen
The Relationship Between Urban Tree Lai And Urban Heat, Amanda Sheepherd, Dr. Ryan Jensen
Journal of Undergraduate Research
It is well known that urban areas are warmer than the surrounding rural areas, with various negative (though sometimes not immediately perceived) consequences for urban residents and the environment. As the world’s human population becomes increasingly urban, methods of mitigating urban heat become more imperative to explore. Though not nearly as abundant as in many natural environments, trees are fairly common in urban areas and can be utilized to offset urban heat. Studying the cooling effects of trees on the surrounding areas can further our understanding of the relationship between trees and temperature. Leaf Area Index (LAI) is a specific …
Holocene Climate Evolution Of Continental Western Eurasia Constrained By Stable-Isotope And Cation Geochemistry Of U-Th-Dated Speleothems And Meteogenic Travertine, Jonathan Lloyd Baker
Holocene Climate Evolution Of Continental Western Eurasia Constrained By Stable-Isotope And Cation Geochemistry Of U-Th-Dated Speleothems And Meteogenic Travertine, Jonathan Lloyd Baker
UNLV Theses, Dissertations, Professional Papers, and Capstones
Reliable reconstructions of global and regional climate during the Holocene (11,700 years ago to present) are vital to constraining the natural range of climate variability and testing state-of-the-art models, which seek to forecast the near- and long-term impact of anthropogenic greenhouse forcing. Much of continental Eurasia is still underrepresented, however, in geological proxy reconstructions of Holocene climate variability, and the vast majority of paleoclimate data only reflect conditions during peak summer months (JJA) or the growing season. The paucity of winter proxy data has therefore been cited as a possible explanation for the current mismatch between geological proxy-based and climate-model …
Petrology And Geochemistry Of The Enriched Poikilitic Shergottite Northwest Africa 10169: Insight Into The Martian Interior, Logan Matthew Combs
Petrology And Geochemistry Of The Enriched Poikilitic Shergottite Northwest Africa 10169: Insight Into The Martian Interior, Logan Matthew Combs
UNLV Theses, Dissertations, Professional Papers, and Capstones
The martian meteorite Northwest Africa (NWA) 10169 is classified as a new member of the geochemically enriched poikilitic shergottites, based on mineral composition, Lu-Hf isotope systematics, and rare earth element (REE) composition. Akin to other poikilitic shergottites, it shows a similar bimodal texture to other enriched and intermediate poikilitic shergottites. In addition, olivine and pyroxene in the poikilitic zone have higher Mg#’s (Mg/Mg+Fe) than those in the interstitial areas, suggesting that the poikilitic texture represents early-stage crystallization, opposed to late-stage non-poikilitic crystallization. Calculated fO2 values are reduced (FMQ -2.3 ± 0.23) within the poikilitic texture, and more oxidized (FMQ -1.07 …
Structural Evolution And Regional Implications Of The Arrowhead Mine Fault Within The Pahranagat Shear Zone, Nevada, Usa, Michael Dennis Evans
Structural Evolution And Regional Implications Of The Arrowhead Mine Fault Within The Pahranagat Shear Zone, Nevada, Usa, Michael Dennis Evans
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Basin and Range province is characterized by normal faults associated with
extension, but the occurrence of strike-slip faults and the seismic hazard accompanying
them is less understood. One major strike-slip zone, the Pahranagat shear zone (PSZ),
lies in Lincoln County, Nevada and within the boundary zone between northern Basin
and Range (NBR) and central Basin and Range (CBR) sub-provinces. The PSZ is a 20-
25 km long zone of Cenozoic left-lateral faults. The Arrowhead Mine Fault (AMF) is one
of the three major faults in the PSZ. The western AMF and the faults that surround and
abut it are …
Miocene-Quaternary Deformation Along The Central Maynard Lake Fault, Pahranagat Shear Zone, Nevada, Alexander Peck
Miocene-Quaternary Deformation Along The Central Maynard Lake Fault, Pahranagat Shear Zone, Nevada, Alexander Peck
UNLV Theses, Dissertations, Professional Papers, and Capstones
The left-lateral Pahranagat shear zone (PSZ) and Caliente-Enterprise zone (CEZ) exist at the boundary between two sub-provinces, the Northern (NBR) and Central Basin and Range (CBR). The PSZ contains three major ENE striking sinistral faults, including the Maynard Lake fault (MLF), which is the longest fault and marks the southern boundary of the zone. The PSZ has been suggested to be a transfer zone, but little is known about the structures along these major faults that are involved in strain transfer. These left-lateral systems exist within the Central Nevada seismic belt which has experienced significant earthquakes in recent history. Possible …
A Novel Approach To Analyzing Strain Heterogeneity In Polycrystalline Quartz Specimens Deformed At High Pressure And Temperature, Nolan Ambrose Regis
A Novel Approach To Analyzing Strain Heterogeneity In Polycrystalline Quartz Specimens Deformed At High Pressure And Temperature, Nolan Ambrose Regis
UNLV Theses, Dissertations, Professional Papers, and Capstones
Rheological studies of rocks and minerals allow researchers to study the grain-scale deformation mechanisms that govern large-scale geologic processes from mountain building to mantle mixing. Deforming rock samples with high pressure and temperature apparatuses similar to the Griggs piston cylinder apparatus allows us to simulate deformation at depth. However, many apparatuses are limited to “cook-and-look” analysis and require modeling techniques to determine the evolution of deformation patterns found in experimental samples. A previous study used two-dimensional finite element models to analyze the development of stress and strain patterns in polycrystalline rocks. The study suggested rhythmic patterns in deformed rocks develop …