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Articles 31 - 60 of 572
Full-Text Articles in Physical Sciences and Mathematics
Seismic Anisotropy And Mantle Deformation Beneath The Central Sunda Plate, Wenkai Song, Youqiang Yu, Stephen S. Gao, Kelly H. Liu, Yifang Fu
Seismic Anisotropy And Mantle Deformation Beneath The Central Sunda Plate, Wenkai Song, Youqiang Yu, Stephen S. Gao, Kelly H. Liu, Yifang Fu
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The central Sunda plate, which forms the core of Southeast Asia, has been extensively studied based on analyses of data mainly from surface geological observations. In contrast, largely due to the limited coverage by seismic stations in the area, a number of key issues associated with mantle structure and dynamics remain enigmatic. These can possibly be constrained by investigating seismic azimuthal anisotropy in the upper mantle. Here we employ the shear wave splitting technique on three P-to-S converted phases from the core-mantle boundary (PKS, SKKS, and SKS) recorded by 11 stations to systematically explore the spatial variation of azimuthal anisotropy …
High-Precision U-Pb Age Constraints On The Permian Floral Turnovers, Paleoclimate Change, And Tectonics Of The North China Block, Qiong Wu, Jahandar Ramezani, Hua Zhang, Jun Wang, Wan Yang, For Full List Of Authors, See Publisher's Website.
High-Precision U-Pb Age Constraints On The Permian Floral Turnovers, Paleoclimate Change, And Tectonics Of The North China Block, Qiong Wu, Jahandar Ramezani, Hua Zhang, Jun Wang, Wan Yang, For Full List Of Authors, See Publisher's Website.
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The Permian marine-terrestrial system of the North China block provides an exceptional window into the evolution of northern temperate ecosystems during the critical transition from icehouse to greenhouse following the late Paleozoic ice age (LPIA). Despite many studies on its rich hydrocarbon reserves and climate-sensitive fossil flora, uncertain temporal constraints and correlations have hampered a thorough understanding of the records of geologic, biologic, and climatic change from the North China block. We present a new chronostratigraphy based on high-precision U-Pb chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) geochronology of tuffs from a near-complete latest Carboniferous-Permian succession in North China. The …
Characterization And Oil Recovery Enhancement By A Polymeric Nanogel Combined With Surfactant For Sandstone Reservoirs, Mustafa Mohammed Almahfood, Baojun Bai
Characterization And Oil Recovery Enhancement By A Polymeric Nanogel Combined With Surfactant For Sandstone Reservoirs, Mustafa Mohammed Almahfood, Baojun Bai
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The characterization and enhanced oil recovery mechanisms of a nanosized polymeric cross-linked gel are presented herein. A negatively charged nanogel was synthesized using a typical free radical suspension polymerization process by employing 2-acrylamido 2-methyl propane sulfonic acid monomer. The synthesized nanogel showed a narrow size distribution with one peak pointing to a predominant homogeneous droplet size. The charged nanogels were also able to adsorb at the oil-water interfaces to reduce interfacial tension and stabilize oil-in-water emulsions, which ultimately improved the recovered oil from hydrocarbon reservoirs. In addition, a fixed concentration of negatively charged surfactant (sodium dodecyl sulfate or SDS) was …
Concentrated Lunar Resources: Imminent Implications For Governance And Justice, Martin Elvis, Alanna Krolikowski, Tony Milligan
Concentrated Lunar Resources: Imminent Implications For Governance And Justice, Martin Elvis, Alanna Krolikowski, Tony Milligan
History and Political Science Faculty Research & Creative Works
Numerous missions planned for the next decade are likely to target a handful of small sites of interest on the Moon's surface, creating risks of crowding and interference at these locations. The Moon presents finite and scarce areas with rare topography or concentrations of resources of special value. Locations of interest to science, notably for astronomy, include the Peaks of Eternal Light, the coldest of the cold traps and smooth areas on the far side. Regions richest in physical resources could also be uniquely suited to settlement and commerce. Such sites of interest are both few and small. Typically, there …
The Pilot Knob Magnetite, Pilot Knob Hematite, And Shepherd Mountain Iron Oxide Deposits In Southeast Missouri -- Local Expressions Of A Magmatic-Hydrothermal Plumbing System?, Bolorchimeg N. Tunnell
The Pilot Knob Magnetite, Pilot Knob Hematite, And Shepherd Mountain Iron Oxide Deposits In Southeast Missouri -- Local Expressions Of A Magmatic-Hydrothermal Plumbing System?, Bolorchimeg N. Tunnell
Doctoral Dissertations
“The Southeast Missouri Iron Metallogenic Province in the Midwestern USA contains seven major and several minor IOA/IOCG-type deposits, all of which are spatially associated with the early Mesoproterozoic (1.50-1.44 Ga) magmatism in the St. Francois Mountains terrane. This Ph.D. project focuses on the Pilot Knob deposits, i.e., the deeper largely massive Pilot Knob Magnetite (PKM) and the shallower Pilot Knob Hematite (PKH) deposits, and the Shepherd Mountain deposit that are located less than 2.1 km distance from one another. The first precise age for the formation of the PKM ore is constrained at 1438±5.8 Ma using apatite U-Pb method. Petrographic …
Preclassic Cultural Eutrophication Of Lake Petén Itzá, Lowland Guatemala, By The Early Maya Of Nixtun-Ch'ich', Brooke A. Birkett
Preclassic Cultural Eutrophication Of Lake Petén Itzá, Lowland Guatemala, By The Early Maya Of Nixtun-Ch'ich', Brooke A. Birkett
Masters Theses
"Paleolimnological evidence indicates the ancient Maya transformed lowland terrestrial ecosystems by felling forest vegetation to construct large civic-ceremonial centers and expand agriculture. The effects of prehistoric Maya land alterations on lake trophic status, however, remain poorly understood. We analyzed a 515-cm-long sediment core from Lake Petén Itzá, lowland Guatemala, to infer paleoenvironmental changes resulting from Maya occupation of the riparian archaeological site of Nixtun-Ch'ich'. Substantial increases in charcoal and fecal stanol concentrations indicate Maya occupation of the Candelaria Peninsula by the late Early Preclassic period beginning ca. 1400 cal yr Before the Common Era (hereafter BCE), despite scant archaeological evidence …
Neogene Dinoflagellate Cysts From The Tropical Americas, Damian Cardenas
Neogene Dinoflagellate Cysts From The Tropical Americas, Damian Cardenas
Doctoral Dissertations
"Marine palynomorphs, mainly dinoflagellate cysts and acritarchs, constitute excellent proxies for biostratigraphic and paleoceanographic studies in neritic sequences. Neogene marine palynological studies have mostly focused on the Northern Hemisphere, resulting in the scarcity of dinoflagellate cysts and acritarchs from tropical latitudes. Forty samples encompassing the late Chattian-late Burgidalian time interval (~24.1- 17.3 Ma) in the Southern Caribbean were analyzed for their marine palynological contents. A biostratigraphic scheme for the region is proposed and includes the upper Chattian-lower Aquitanian Minisphaeridium latirictum Interval Zone (~23.9-22.0 Ma), the upper Aquitanian Achomosphaera alcicornu Interval Zone (~22.0-20.3 Ma), and the Burdigalian Cribroperidinium tenuitabulatum Interval Zone …
Multiple Generations Of Phlogopite In An Alnöite Diatreme: Insights Into The Petrogenesis Of The Avon Alkaline Igneous Province, Missouri, Nathan Gregory Limbaugh
Multiple Generations Of Phlogopite In An Alnöite Diatreme: Insights Into The Petrogenesis Of The Avon Alkaline Igneous Province, Missouri, Nathan Gregory Limbaugh
Masters Theses
“Alkaline Ultramafic Carbonatite (AUC) complexes, although rare, are valued for diamonds and REEs, and as windows into subcontinental and mantle processes as recorded by rock fabrics, mineral spatial relationships, and mineral compositions. We report specifically on olivine and phlogopite petrographic relationships and compositions from the Devonian alnoite diatreme-facies of the Avon Alkaline Igneous Province, Missouri. The diatreme alnoite is a mixture of domains of olivine magmaclasts (OM) set in a crystal-rich melilite matrix. OM are highly fractured, serpentinized olivine pseudomorphs with variable amounts of pristine olivine fragments. Larger olivine domains typically exhibit clear crystal faces and irregular “channels” indicative of …
Relationships Among Mineralogy, Geochemistry, And Oil And Gas Production In The Tuscaloosa Marine Shale, Hayley Roxana Beitel
Relationships Among Mineralogy, Geochemistry, And Oil And Gas Production In The Tuscaloosa Marine Shale, Hayley Roxana Beitel
Masters Theses
"The Tuscaloosa Marine Shale (TMS) is an unconventional shale reservoir located in southeast Louisiana and southwest Mississippi. Limited mineralogical and geochemical data for the TMS have been published. The data that do exist indicate that the formation is heterogeneous. Consequently, previous investigators and oil and gas companies have not managed to effectively link mineralogical and chemical changes to oil and gas production in the TMS. These linkages are critical to establish for future exploration efforts. In this study, we attempt to establish these relationships by gathering all existing mineralogical and chemical data in the TMS, including newly acquired data from …
Timing Of Deformation Along The Iron Springs Thrust, Southern Sevier Fold-And-Thrust Belt, Utah: Evidence For An Extensive Thrusting Event In The Mid-Cretaceous, J. Daniel Quick, John Patrick Hogan, Michael Wizevich, Jonathan Obrist-Farner, James L. Crowley
Timing Of Deformation Along The Iron Springs Thrust, Southern Sevier Fold-And-Thrust Belt, Utah: Evidence For An Extensive Thrusting Event In The Mid-Cretaceous, J. Daniel Quick, John Patrick Hogan, Michael Wizevich, Jonathan Obrist-Farner, James L. Crowley
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The temporal and spatial distribution of strain associated with the Sevier orogeny in western North America is significantly different in the southern end of the belt, at the latitude of Las Vegas, Nevada, than farther to the north at the latitude of Salt Lake City, Utah. Reasons for these differences have been speculative as a lack of temporal constraints on thrusting in the intervening region hindered along-strike correlation across the belt. We determined a crystallization age of 100.18 ± 0.04 Ma for zircons extracted from a recently recognized dacite lapilli ash-fall tuff near the base of the synorogenic Iron Springs …
Groundwater Withdrawal Prediction Using Integrated Multitemporal Remote Sensing Data Sets And Machine Learning, S. Majumdar, Ryan G. Smith, J. J. Butler, V. Lakshmi
Groundwater Withdrawal Prediction Using Integrated Multitemporal Remote Sensing Data Sets And Machine Learning, S. Majumdar, Ryan G. Smith, J. J. Butler, V. Lakshmi
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Effective monitoring of groundwater withdrawals is necessary to help mitigate the negative impacts of aquifer depletion. In this study, we develop a holistic approach that combines water balance components with a machine learning model to estimate groundwater withdrawals. We use both multitemporal satellite and modeled data from sensors that measure different components of the water balance and land use at varying spatial and temporal resolutions. These remote sensing products include evapotranspiration, precipitation, and land cover. Due to the inherent complexity of integrating these data sets and subsequently relating them to groundwater withdrawals using physical models, we apply random forests -- …
Drastic Vegetation Change In The Guajira Peninsula (Colombia) During The Neogene, Carlos Jaramillo, Pierre Sepulchre, Damian Cardenas, Francisca Oboh-Ikuenobe, For Full List Of Authors, See Publisher's Website.
Drastic Vegetation Change In The Guajira Peninsula (Colombia) During The Neogene, Carlos Jaramillo, Pierre Sepulchre, Damian Cardenas, Francisca Oboh-Ikuenobe, For Full List Of Authors, See Publisher's Website.
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Dry biomes occupy ~35% of the landscape in the Neotropics, but these are heavily human-disturbed. In spite of their importance, we still do not fully understand their origins and how they are sustained. The Guajira Peninsula in northern Colombia is dominated by dry biomes and has a rich Neogene fossil record. Here, we have analyzed its changes in vegetation and precipitation during the Neogene using a fossil pollen and spore dataset of 20 samples taken from a well and we also dated the stratigraphic sequence using microfossils. In addition, we analyzed the pollen and spore contents of 10 Holocene samples …
Slab Dehydration And Mantle Upwelling In The Vicinity Of The Sumatra Subduction Zone: Evidence From Receiver Function Imaging Of Mantle Transition Zone Discontinuities, Fansheng Kong, Stephen S. Gao, Kelly H. Liu, Weiwei Ding, Jiabiao Li
Slab Dehydration And Mantle Upwelling In The Vicinity Of The Sumatra Subduction Zone: Evidence From Receiver Function Imaging Of Mantle Transition Zone Discontinuities, Fansheng Kong, Stephen S. Gao, Kelly H. Liu, Weiwei Ding, Jiabiao Li
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
A total of 10,586 P-to-S radial receiver functions recorded by 64 broadband seismic stations were utilized to image the 410 and 660 km discontinuities (d410 and d660, respectively) bordering the mantle transition zone (MTZ) beneath the Sumatra Island, the Malay Peninsula, and the western margin of the South China Sea. The d410 and d660 were imaged by stacking receiver functions in successive circular bins with a radius of 1°, after moveout corrections based on the 1-D IASP91 Earth model. The resulting apparent depths of the discontinuities exhibit significant and spatially systematic variations. The apparent depths of the d410 and d660 …
Topography Of The 410 And 660 Km Discontinuities Beneath The Cenozoic Okavango Rift Zone And Adjacent Precambrian Provinces, Youqiang Yu, Stephen S. Gao, Kelly H. Liu
Topography Of The 410 And 660 Km Discontinuities Beneath The Cenozoic Okavango Rift Zone And Adjacent Precambrian Provinces, Youqiang Yu, Stephen S. Gao, Kelly H. Liu
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
By taking advantage of the recent availability of a broadband seismic data set from Networks NR and BX covering the entire country of Botswana, we conduct a systematic receiver function investigation of the topography of the 410 and 660 km discontinuities beneath the incipient Okavango rift zone (ORZ) in northern Botswana and its adjacent Archean-Proterozoic tectonic provinces in southern Africa. Similar to a previous mantle transition zone (MTZ) discontinuity study using data from a 1-D profile traversing the ORZ, a normal MTZ thickness is observed in most parts of the study area. This is inconsistent with the existence of widespread …
Groundwater Storage Loss Associated With Land Subsidence In Western United States Mapped Using Machine Learning, Ryan G. Smith, Sayantan Majumdar
Groundwater Storage Loss Associated With Land Subsidence In Western United States Mapped Using Machine Learning, Ryan G. Smith, Sayantan Majumdar
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Land subsidence caused by groundwater extraction has numerous negative consequences, such as loss of groundwater storage and damage to infrastructure. Understanding the magnitude, timing, and locations of land subsidence, as well as the mechanisms driving it, is crucial to implementing mitigation strategies, yet the complex, nonlinear processes causing subsidence are difficult to quantify. Physical models relating groundwater flux to aquifer compaction exist but require substantial hydrological data sets and are time consuming to calibrate. Land deformation can be measured using interferometric synthetic aperture radar (InSAR) and GPS, but the former is computationally expensive to estimate at scale and is subject …
A Bayesian Framework To Unravel Food, Groundwater, And Climate Linkages: A Case Study From Louisiana, Nitin K. Singh, Ruchi Bhattacharya, David M. Borrok
A Bayesian Framework To Unravel Food, Groundwater, And Climate Linkages: A Case Study From Louisiana, Nitin K. Singh, Ruchi Bhattacharya, David M. Borrok
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Advancing our understanding of the connections among groundwater, food, and climate is critical to meet global food demands while optimizing water resources usage. However, our understanding of the linkages among groundwater, food, and climate is still limited. Here, we offer a Bayesian framework to simulate crop yield at a regional scale and quantify its relationships and associated uncertainty with climate, groundwater, agricultural, and energy-related variables. We implemented the framework in the rice-producing regions of Louisiana from 1960-2015. To build a parsimonious model, we used a probability-based variable selection approach to detect the key drivers of rice yield. Rice yield increased, …
Receiver Function Imaging Of The 410 And 660 Km Discontinuities Beneath The Australian Continent, Kailun Ba, Stephen S. Gao, Kelly H. Liu, Fansheng Kong, Jianguo Song
Receiver Function Imaging Of The 410 And 660 Km Discontinuities Beneath The Australian Continent, Kailun Ba, Stephen S. Gao, Kelly H. Liu, Fansheng Kong, Jianguo Song
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
To provide constraints on a number of significant controversial issues related to the structure and dynamics of the Australian continent, we utilize P-to-S receiver functions (RFs) recorded by 182 stations to map the 410 and 660 km discontinuities (d410 and d660, respectively) bordering the mantle transition zone (MTZ). The RFs are stacked in successive circular bins with a radius of 1° under a non-plane wave front assumption. The d410 and d660 depths obtained using the 1-D IASP91 earth model show a systematic apparent uplifting of about 15 km for both discontinuities in central and western Australia relative to eastern Australia, …
Mantle Structure And Flow Beneath An Early-Stage Continental Rift: Constraints From P Wave Anisotropic Tomography, Youqiang Yu, Stephen S. Gao, Dapeng Zhao, Kelly H. Liu
Mantle Structure And Flow Beneath An Early-Stage Continental Rift: Constraints From P Wave Anisotropic Tomography, Youqiang Yu, Stephen S. Gao, Dapeng Zhao, Kelly H. Liu
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
To explore 3-D seismic velocity and radial anisotropy structures of the upper mantle and mantle transition zone beneath the Malawi and Luangwa rift zones of the East African Rift System, we conduct the first study of P wave anisotropic tomography using data recorded at 75 seismic stations including 34 stations that we installed along two profiles as part of the Seismic Arrays for African Rift Initiation experiment. Both rift zones are revealed to have normal or slightly low velocity anomalies in the lithosphere and upper asthenosphere. The surrounding cratonic lithosphere is characterized by high-velocity anomalies with amplitudes ranging from +1.0% …
Strain Partitioning Across The Polochic-Motagua Fault System In Guatemala: Insight From Kinematic Modeling, Qiaoqi Sun
Strain Partitioning Across The Polochic-Motagua Fault System In Guatemala: Insight From Kinematic Modeling, Qiaoqi Sun
Masters Theses
”The Polochic-Motagua Fault System in Guatemala is the on-land segment of the sinistral transform plate boundary between the North American Plate and the Caribbean Plate. Three major seismically active strike-slip faults in this fault system pose significant earthquake threats to surrounding populated cities. The assessment of seismic hazard requires a better understanding of the kinematics of the fault system. GPS monitoring indicates that seventy-five percent of the ~20 mm/yr. plate motion is accommodated by the Motagua Fault and less than twenty-five percent is accommodated by the Polochic Fault. However, the Polochic Fault documents a lateral offset of ~132 ± 5 …
An Integrated Wellbore Stability Study To Mitigate Expensive Wellbore Instability Problems While Drilling Into Zubair Shale/Sand Sequence, Southern Iraq, Ahmed Khudhair Abbas
An Integrated Wellbore Stability Study To Mitigate Expensive Wellbore Instability Problems While Drilling Into Zubair Shale/Sand Sequence, Southern Iraq, Ahmed Khudhair Abbas
Doctoral Dissertations
”The Zubair Formation is the most prolific reservoir in Iraq, which is comprised of sandstones interbedded with shale sequences. Due to the weak nature of the shale sequence, the instability of a wellbore is one of the most critical challenges that continuously appears during drilling across this formation. Historically, over 90% of wellbore problems in the Zubair Formation were due to wellbore instability. Problems associated with wellbore instability, such as tight hole, shale caving, stuck logging tools along with subsequent fishing, stuck pipe, and sidetracking result in increasing the non-productive time. This non-productive time has cost an enormous amount of …
The Role Of Tectonic Inheritance, Plate-Reorganization, And Magma Flare-Ups In The Evolution Of The Sevier Orogeny, J. Daniel Quick
The Role Of Tectonic Inheritance, Plate-Reorganization, And Magma Flare-Ups In The Evolution Of The Sevier Orogeny, J. Daniel Quick
Masters Theses
"The temporal and spatial distribution of strain associated with the Sevier Orogeny in western North America is significantly different in the southern end of the belt, at the latitude of Las Vegas, than further to the north at the latitude of Salt Lake City. Until this study, reasons for these differences were speculative as a lack of thrust kinematic data in the intervening region hindered along strike correlation across the belt. A crystallization age of 100.18 ± 14 0.04 Ma was determined for zircons extracted from a recently recognized ash fall tuff near the base of the synorogenic Iron Springs …
Predictive Geohazard Mapping Using Lidar And Satellite Imagery In Missouri And Oklahoma, Usa, Olufeyisayo B. Ilesanmi
Predictive Geohazard Mapping Using Lidar And Satellite Imagery In Missouri And Oklahoma, Usa, Olufeyisayo B. Ilesanmi
Doctoral Dissertations
”Light Detection and Ranging (LiDAR) and satellite imagery have become the most utilized remote sensing technologies for compiling inventories of surficial geologic conditions. Point cloud data obtained from multi-spectral remote sensing methods provide a detailed characterization of the surface features, in particular, the detailed surface manifestations of underlying geologic structures. When combined, point clouds eliminate bias from visual inconsistencies and/or statistical values. This research explores the competence of point clouds derived from LiDAR and Unmanned Aerial Systems (UAS) as a predictive tool in evaluating various geohazards. It combines these data sets with other remote sensing techniques to evaluate the sensitivity …
Mineral Compositions Of Meteorite Samples Alha 77005, Nwa 7397, Nwa 5480, And Ausson: Implications For Geodynamic Processes On Their Parent Bodies And Meteorite Reclassification, Kaylin Agnata Tunnell
Mineral Compositions Of Meteorite Samples Alha 77005, Nwa 7397, Nwa 5480, And Ausson: Implications For Geodynamic Processes On Their Parent Bodies And Meteorite Reclassification, Kaylin Agnata Tunnell
Masters Theses
“This study investigates the major, minor, and trace element compositions of minerals from a series of meteorites which represent different stages of planetary evolution including two sample from Mars (ALHA 77005 and NWA 7397), one sample from Vesta (NWA 5480), and one ordinary chondrite (Ausson). The goal of this study is to investigate if petrogenetic tracers commonly employed to understand terrestrial samples can also be applied to extraterrestrial samples. The data presented here show that mineral trace element data allow for novel insight into the magmatic history of meteorite samples. For example, V/Sc and Fe/Mn ratios in olivine provide insight …
A Broad Iceland Plume Associated With Two Phase Transitions At The 660 Km Discontinuity: Constraints From Receiver Functions, Dan Wang
Doctoral Dissertations
"In spite of the fact that Iceland is frequently regarded as the archetypal example of mantle plumes, the existence, depth extent, origin, dimension and excess temperature of the hypothesized plume remain enigmatic and hotly debated. The controversy mostly originates from the limited vertical resolution of seismic tomography techniques and the associated uncertainty in the depth and lateral extents of the lower wavespeed anomaly. Here we utilize a robust receiver-function-based technique to image the topography of the 410 and 660 km discontinuities bordering the mantle transition zone beneath Iceland and surrounding oceanic regions, and construct thermal and seismic wavespeed models of …
Seismological Investigations Of Lithospheric Structure Beneath The East African Rift System And The Kalahari Craton, Tuo Wang
Doctoral Dissertations
"In spite of numerous geophysical studies have been conducted in East African Rift System and Southern Africa, the structure and evolution of the crust and upper mantle are still controversial. In this study, we applied multiple seismological techniques to investigate the structure in the crust and uppermost mantle beneath the East African Rift System and Kalahari Craton in southern Africa. First, the technique of ambient noise tomography was applied to image shear wave velocity model from surface to the depth of 40 km beneath the Malawi and Luangwa rift zones. For the first time, a high-resolution 3-D shear wave velocity …
History Of Natural And Anthropogenic Activities In Lake Izabal, Eastern Guatemala: Using Geochemical Evidence To Record Recent Contamination, Elisandra Hernandez
History Of Natural And Anthropogenic Activities In Lake Izabal, Eastern Guatemala: Using Geochemical Evidence To Record Recent Contamination, Elisandra Hernandez
Doctoral Dissertations
”Water is essential for human subsistence. Stable freshwater supplies are needed as a source of food, drinking water, for transportation, recreation and economic development. Despite their recognized importance, anthropogenic activities have altered freshwater ecosystems around the world. Lake Izabal is the habitat for diverse aquatic species of flora and fauna, some of which are endemic and endangered. Its importance notwithstanding, anthropogenic activities developed in Lake Izabal’s catchment in recent years have compromised its status. This study used paleolimnological techniques to link past and recent anthropogenic activities such as mining operations and recent tilapia aquaculture. Relative abundances and concentrations of Pb, …
A Granger Causality Analysis Of Groundwater Patterns Over A Half-Century, Nitin K. Singh, David M. Borrok
A Granger Causality Analysis Of Groundwater Patterns Over A Half-Century, Nitin K. Singh, David M. Borrok
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Groundwater depletion in many areas of the world has been broadly attributed to irrigation. However, more formal, data-driven, causal mechanisms of long-term groundwater patterns have not been assessed. Here, we conducted the first Granger causality analysis to identify the "causes" of groundwater patterns using the rice-producing parishes of Louisiana, USA, as an example. Trend analysis showed a decline of up to 6 m in groundwater level over 51 years. We found that no single cause explained groundwater patterns for all parishes. Causal linkages were noted between groundwater and area harvested, number of irrigation wells, summer precipitation totals, and drought. Bi-directional …
Extraction And Visualization Of Orientation Data From Virtual Geologic Surfaces With Matlab®, Avery J. Welker, John Patrick Hogan, Andreas Eckert
Extraction And Visualization Of Orientation Data From Virtual Geologic Surfaces With Matlab®, Avery J. Welker, John Patrick Hogan, Andreas Eckert
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
High-resolution visualization of surfaces of geologic interest, at a multitude of scales, using 3D point cloud technologies provides an opportunity to analyze spatial relationships of surfaces using orientation data. We present a MATLAB® script that produces planar geologic attitude data (e.g., strike, dip, and dip-direction data) from 3D datasets (e.g., point clouds, 3D scanning). The method utilizes Cartesian coordinates of triangular planar surfaces and converts them into matrices of conventional geologic attitude data. Spatial relationships among data points can be investigated, using polar tangent diagrams, stereographic analysis, or geologic curvature analysis. We utilize this script to create "synthetic" graphical plots …
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
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 …
Modeling Land Subsidence Using Insar And Airborne Electromagnetic Data, Ryan G. Smith, R. Knight
Modeling Land Subsidence Using Insar And Airborne Electromagnetic Data, Ryan G. Smith, R. Knight
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Land subsidence as a result of groundwater overpumping in the San Joaquin Valley, California, is associated with the loss of groundwater storage and aquifer contamination. Although the physical processes governing land subsidence are well understood, building predictive models of subsidence is challenging because so much subsurface information is required to do so accurately. For the first time, we integrate airborne electromagnetic data, representing the subsurface, with subsidence data, mapped by interferometric synthetic aperture radar (InSAR), to model deformation. By combining both data sets, we are able to solve for hydrologic and geophysical properties of the subsurface to effectively model the …