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Articles 211 - 237 of 237
Full-Text Articles in Earth Sciences
Correlation Of Sequence Stratigraphic Surfaces Of The Mid-Cretaceous Dakota Group From Subsurface To Outcrop Southern Denver Basin, Colorado., Yaqoub Y Y S M Alsayed Alrefaei
Correlation Of Sequence Stratigraphic Surfaces Of The Mid-Cretaceous Dakota Group From Subsurface To Outcrop Southern Denver Basin, Colorado., Yaqoub Y Y S M Alsayed Alrefaei
Earth & Environmental Sciences Theses - Archive
The D and J sandstone of the Cretaceous Dakota Group are considered as the major oil and gas producing units within in the Denver Basin. The distribution of these units in the Denver Basin is a sub-basin of the Early Cretaceous Western Interior Basin .These units are well understood within the northern Denver Basin and the linkage between the subsurface units and their equivalents in outcrop in the Front Range is well-established. They have gained less attention in southern parts of the basin and the linkage between the subsurface units and their equivalents in southern outcrop is not yet established. …
Chemostratigraphy And Paleoceanography Of The Mississippian Barnett Formation, Southern Fort Worth Basin, Texas, Usa, James Daniel Hoelke
Chemostratigraphy And Paleoceanography Of The Mississippian Barnett Formation, Southern Fort Worth Basin, Texas, Usa, James Daniel Hoelke
Earth & Environmental Sciences Theses - Archive
The Mississippian (Visean-Serpukhovian) Barnett Formation is a lithologic unit composed primarily of laminated siliceous mudstone and calcareous siliceous mudstone with significant phosphate and sulfide phases present. The Barnett Formation was deposited in the Fort Worth Basin, a marine foreland basin that formed as a result of the early Ouachita Orogeny from the collision of Laurasia and Gondwana. In this study we used a variety of geochemical methods to provide a detailed assessment of the chemostratigraphy and paleoceanography of the Barnett Formation in the southern end of the Fort Worth Basin in Texas. Various aspects of the Barnett Formation studied include: …
Thermal Maturity And Porosity Development During Catagensis In The Barnett Shale, Fort Worth Basin, Texas, Nathan Glondys
Thermal Maturity And Porosity Development During Catagensis In The Barnett Shale, Fort Worth Basin, Texas, Nathan Glondys
Earth & Environmental Sciences Theses - Archive
Unconventional resource plays are typified by significantly recoverable volumes of thermally mature hydrocarbons (oil, condensate and/or gases) trapped within a low permeability shale formation acting as source, reservoir and seal. These systems pose a scientific and engineering challenge to produce recoverable hydrocarbons from, chiefly due to their low permeabilities. There is growing evidence that secondary porosity in organic gas bearing shales is created during the thermal maturation of kerogen. A better understanding of porosity development during maturation of mobile organics during catagenesis may yield new insight on how we view these systems. A comparative analysis of the gas phase(s), peak …
Trace Element Geochemistry In Groundwater Flow Systems, Stephanie Scholten Willis
Trace Element Geochemistry In Groundwater Flow Systems, Stephanie Scholten Willis
Earth & Environmental Sciences Dissertations - Archive
This research focuses on trace element geochemistry in three groundwater flow systems: the Carrizo Sand, the Upper Floridan, and the Aquia aquifers. The focus is threefold: (i) studying the geochemical behavior, concentrations, and fractionation patterns of rare earth elements (REEs) along two flow paths by examination of both groundwater and sediment samples, (ii) investigating the behavior of arsenic (As) and antimony (Sb) and comparing these data to reveal the biogeochemical processes affecting As and Sb concentrations and speciation as well as determining correlations between As and Sb concentrations, and (iii) formulating adsorption isotherms to demonstrate the adsorption capacity of As …
Verrucomicrobia: A Model Phylum To Study The Effects Of Deforestation On Microbial Diversity In Amazon Forest, Kshitij Ranjan
Verrucomicrobia: A Model Phylum To Study The Effects Of Deforestation On Microbial Diversity In Amazon Forest, Kshitij Ranjan
Earth & Environmental Sciences Theses - Archive
The Amazon rainforest is known for having a very high diversity of plants and animals. However, it is one of the least understood ecosystems regarding microbial diversity. Microorganisms are important for the ecological balance of any ecosystem and play important role in various biogeochemical cycles. As the Amazon rainforest undergoes to rapid deforestation, loss of its biodiversity is expected. This research aims to determine the effects of deforestation on the soil microbial diversity of the Amazon forest. Toward this, we selected the phylum Verrucomicrobia as a model for observing changes in the microbial structure of rainforest soils. Samples were collected …
Growth And Toxicity Of Prymnesium Parvum In Long-Term Cultures At Low Temperature And Salinity, Xianzi He
Growth And Toxicity Of Prymnesium Parvum In Long-Term Cultures At Low Temperature And Salinity, Xianzi He
Earth & Environmental Sciences Theses - Archive
There is a paradox reported concerning observations of toxic blooms of Prymnesium parvum in winter in Texas (USA), and its growth performance in the laboratlry. Culture experiments indicate relatively high optimum temperature and salinity for growth, conditions different from those ofwinter in Texas. Because previous laboratory experiments were of short duration, it was suggested that long-term culturing of many generations could allow physiological and epigenetic changes, as well as natural selection to take place, leading to improved growth performance at low temperature and salinity. In this study, the growth and toxicity of P. parvum was investigated under relatively low temperature …
Microfacies Analysis Of The Jacksboro Limestone Member (Graham Formation, Virgilian, Pennsylvanian) In Jack County, Texas, Claudio Manuel Leyva
Microfacies Analysis Of The Jacksboro Limestone Member (Graham Formation, Virgilian, Pennsylvanian) In Jack County, Texas, Claudio Manuel Leyva
Earth & Environmental Sciences Theses - Archive
The Jacksboro Limestone is a member of the Graham Formation of the Virgilian (Upper Pennsylvanian) and is exposed only in and around the city of Jacksboro in central Jack County, Texas. The purposes of this investigation were to study the vertical and lateral microfacies changes that occur throughout the Jacksboro Limestone in its outcrop belt and to discuss its relationship as the basal regressive cycle in the Virgilian part of the Pennsylvanian, in particular: (1) describe and classify the primary limestone lithofacies on the basis of carbonate rock textures, (2) interpret, if possible, the depositional environment and physical energy of …
Leading The James: The Morphological Changes Of The Missouri River And The Subservient James River, April Deann Moreno
Leading The James: The Morphological Changes Of The Missouri River And The Subservient James River, April Deann Moreno
Earth & Environmental Sciences Theses - Archive
The James River flows into the Missouri River east of Yankton, SD. The degree to which the morphological changes of the Missouri River had an impact on the course of the James River is debatable. After mapping the Mission Hill and Menominee quadrangles, surficial maps have been made showing the preserved allounits of the area. Hand augers were used to ground-truth surface features located through the use of aerial photographs, topographic maps, and to confirm features on the surficial maps made. OSL samples were taken from both quadrangles and also from Meckling and Saint Helena; the latter two were mapped …
Fluvial Architecture And Geometry Of The Mungaroo Formation Of Rankin Trend On The Northwest Shelf Of Australia, Scott Bradley Stoner
Fluvial Architecture And Geometry Of The Mungaroo Formation Of Rankin Trend On The Northwest Shelf Of Australia, Scott Bradley Stoner
Earth & Environmental Sciences Theses - Archive
The Northwest Shelf of Australia contains many producing world class gas reservoirs with large areas remaining unexplored. The fluvio-deltaic Mungaroo Formation of Rankin Trend on the Northwest Shelf is the site of many producing fields on the Northwest Shelf and data collected from these sites is invaluable in understanding the architecture and geometry of the fluvial strata that house these reservoirs. The Mungaroo Formation contains alternating sections of low accommodation amalgamated sand bodies, and high accommodation shale prone sections that record architecturally complex floodplain deposits. The study sections were broken down into eight architectural elements; thalweg fill, unit bar, abandonment …
Sedimentology, Ichnology, Depositional Environment Interpretation, And Reservoir Characterization In The Cotton Valley Formation Sandstone In The Amoco Grace Lowry #1, Harrison County, Texas, Justin D. Bagley
Earth & Environmental Sciences Theses - Archive
The Cotton Valley formation in east Texas and north Louisiana is a proven hydrocarbon producing tight gas sand reservoir. Understanding the depositional environment, sandstone body geometries and reservoir properties are important for exploration and development. Two hundred and thirty eight feet of conventional core, over the Cotton Valley sandstone interval, was described and interpreted from the Amoco Grace Lowry #1, located in Harrison County, Texas. The sedimentology and ichnology as well as the net sandstone isopachous maps provided the basis for the depositional environment interpretation. Core plug derived porosity and permeability, electric logs, and thin sections were utilized for reservoir …
A Geologic Map And Stratigraphy Of Upper Guadalupian - Lower Ochoan (Permian) Strata Along And East Of Fm 2185 In The Northwestern Apache Mountains Near Van Horn, West Texas, Michael James Sweatt
A Geologic Map And Stratigraphy Of Upper Guadalupian - Lower Ochoan (Permian) Strata Along And East Of Fm 2185 In The Northwestern Apache Mountains Near Van Horn, West Texas, Michael James Sweatt
Earth & Environmental Sciences Theses - Archive
A surface geologic map is constructed for an area of approximately four square miles east of Texas FM 2185, 35 miles northeast of Van Horn, West Texas in the northwestern part of the Apache Mountains. Middle Permian Guadalupian-Late Permian Ochoan age strata containing Capitan Reef debris and shelf to basinal beds are exposed and can be correlated to similar age strata of the Guadalupe Mountains to the north and northwest of the map area. In the area of study, three formations of the uppermost Middle and Upper Permian, Bell Canyon, Castile, and Rustler, expose strata that can be seen in …
On The Sensitivity Of Ocean Circulation To Arctic Freshwater Pulses During The Paleocene/Eocene Thermal Maximum, Jesse Tiner Cope
On The Sensitivity Of Ocean Circulation To Arctic Freshwater Pulses During The Paleocene/Eocene Thermal Maximum, Jesse Tiner Cope
Earth & Environmental Sciences Theses - Archive
The Paleocene/Eocene Thermal Maximum (PETM) corresponds to a period characterized by extreme global warming caused by a massive carbon input into the ocean and atmosphere. Approximately 55 Ma in the early Cenozoic, evidence suggests an ice-free Arctic exchanged relatively fresh water with the remainder of the global ocean. In this study we use the Community Climate Systems Model version 3 (CCSM-3), including a carbon cycle model, to examine the sensitivity of deep-water formation and circulation within the global ocean to freshwater exchange from the Arctic Ocean during the PETM. Past modeling experiments show how alterations to seaway exchanges can have …
Seismic Inversion In Fluvial Reservoirs: Building A Geologic Model-Based Inversion For The Stratton Field 3d Survey, Richard Charles Odom
Seismic Inversion In Fluvial Reservoirs: Building A Geologic Model-Based Inversion For The Stratton Field 3d Survey, Richard Charles Odom
Earth & Environmental Sciences Theses - Archive
Seismic surveys, in particular 3-D surveys, are an important tool for imaging geologic structure in the subsurface; they are routinely applied to map structural trends and geometry to define the reservoir structure. Many of the world's oil and gas reservoirs are sands deposited by river systems but the scales of fluvial architectural elements challenge the resolution of the seismic method. One such challenging field is the Stratton field in the FR-4 Gas Play of south Texas; the reservoir is Frio formation, a thick collection (greater than 3000 feet) of stacked fluvial deposits consisting of thin channels and splays of reservoir …
Geochemistry Of Molybdenum In The Aquia Aquifer, Maryland, Usa, Teresa Iafelice Valle
Geochemistry Of Molybdenum In The Aquia Aquifer, Maryland, Usa, Teresa Iafelice Valle
Earth & Environmental Sciences Theses - Archive
The present study contributes to the understanding of controls on and behavior of molybdenum (Mo) in an aquifer, and its potential as an indicator of changing redox conditions along the groundwater flowpath. The central hypothesis of the present work is that the hydrogeochemical evolution along two separate groundwater flowpaths of the Aquia Aquifer, Maryland, USA, one each on the Eastern and Western Shore of Chesapeake Bay, consists of chemical weathering and oxidation-reduction reactions that dictate the degree of Mo mobilization, as well as mineral co-precipitation/re-adsorption reactions that dictate the degree of Mo immobilization (i.e., scavenging). This hypothesis is evaluated by …
Removal Of Butylene And Propylene Gas Using Biofiltration, Madhu Rani
Removal Of Butylene And Propylene Gas Using Biofiltration, Madhu Rani
Earth & Environmental Sciences Theses - Archive
Air pollutants are produced from a variety of anthropogenic activities such as food production, wastewater treatment plants, painting, industrial activities, and biomass combustion. Such pollutants are becoming a cause of concern worldwide because of their harmful effects on ecosystems, human health, and the atmosphere. One technology for treatment of these hazardous, odorous, and ozone-forming compounds is biofiltration. Biofilters are relatively inexpensive to install and operate, and can achieve high pollution removal efficiencies. This research was carried out to determine the removal efficiency of pollutants propylene and butylene using biofilter technology. In a biofilter column, air is passed through a packed …
Studies Of The Performance, Stability And Reliability Of Various Configurations Of The Activated Sludge Process At Full-Scale Municipal Wastewater Treatment Plants, Michael A. Redda
Earth & Environmental Sciences Dissertations - Archive
This research presents a performance, stability and reliability analysis of five configurations of activated sludge process, viz., conventional, contact stabilization, complete mix, extended aeration and sequencing batch reactor. Five years effluent records of carbonaceous biochemical oxygen demand (CBOD5), total suspended solids (TSS) and ammonia nitrogen (NH3-N) were used. The impact of hydraulic load classes (HLCes) and seasons on the performance of configurations were also examined. The Univariate General Linear Model with Tukey's Honestly Significant Difference was employed in the performance and stability studies. Performance was determined based on the observed lowest mean effluent concentrations, while the observed standard deviation from …
Geochemical Investigation Of Tungsten In Two Groundwater Flow Systems: The Carrizo Sand Aquifer, Texas, Usa, And The Aquia Aquifer, Maryland, Usa, Heeral B. Dave
Earth & Environmental Sciences Theses - Archive
Groundwater sampled were collected from well sites located within the Carrizo Sand aquifer in Atascosa and McMullen counties in Texas, and also within the Aquia Aquifer, Maryland in the counties of Queen Anne's, Kent, and Ann Arundel in Maryland. During the field sampling trips, on site measurements were conducted for pH, specific conductance, temperature, alkalinity, dissolved oxygen (DO), oxidation-reduction potential (Eh), iron speciation ([Fe (II)/ Fe(III)]), and dissolved S (-II) concentrations. In order to examine and study solid phase tungsten concentrations in the Aquia (archived at the Maryland Geological Survey) and Carrizo Aquifer sediments, we collected a number of aliquots, …
Southern Illinois Paleoclimate Determined From Variations In Iron Oxide Content, James Lee Blankenship
Southern Illinois Paleoclimate Determined From Variations In Iron Oxide Content, James Lee Blankenship
Earth & Environmental Sciences Theses - Archive
Diffuse reflectance spectroscopy was used to determine the relative abundance of the iron oxides hematite and goethite in a loess and paleosol sequence from an unglaciated area of southern Illinois. Factor analysis of first derivatives of the spectral data yielded a four factor solution which explained more than 94% of the cumulative variance. Factors 2 and 3, which represent hematite and goethite respectively, were the most useful for interpreting paleoclimatic conditions at the site. Hematite, which is indicative of warmer conditions with periodic seasonal rainfall, shows a strong response not only to climatic variations but also to glacial lobe proximity. …
Geology Of The Northwestern Apache Mountains, Southeast Culberson County, West Texas, U.S.A., Walter Lyman Kennedy
Geology Of The Northwestern Apache Mountains, Southeast Culberson County, West Texas, U.S.A., Walter Lyman Kennedy
Earth & Environmental Sciences Theses - Archive
Middle Permian marine (Bell Canyon Formation) strata along the southwestern margin of the Delaware Basin in southeastern Culberson County, Texas provide excellent exposures of basinal and slope strata, useful fossils for age dating, and a variety of interpretations of possible depositional environments. This work includes a detailed surficial geologic map of about a seven square kilometer area of the northwestern Apache Mountains, located along a portion of Texas Farm Road 2185, about 60 kilometers northeast of Van Horn, Texas. In addition to the map, a stratigraphic column is presented along with descriptions of a major subaqueous gravity flow in the …
West Nile Virus Monitoring In North Central Texas And A Proposed Surveillance Model, Mark Edward Dinubila
West Nile Virus Monitoring In North Central Texas And A Proposed Surveillance Model, Mark Edward Dinubila
Earth & Environmental Sciences Theses - Archive
West Nile virus monitoring among mosquito populations in Tarrant County, Texas has been ongoing for more than 4 years. Coupled with RT-PCR Testing by the North Texas Regional Laboratory, Tarrant County and the cities that reside within its borders have been able to get an estimate of the location of the virus in their cities. As the participants select trap locations based on convenience, past experience and public interest, it should be beneficial to use geomorphological characteristics to dictate future trapping locations. This surveillance model using existing land maps of Tarrant County, past trap locations and their test results. The …
Salinity, Ph, Temperature, Desiccation And Hypoxia Tolerance In The Invasive Freshwater Apple Snail Pomacea Insularum, Veena Ramakrishnan
Salinity, Ph, Temperature, Desiccation And Hypoxia Tolerance In The Invasive Freshwater Apple Snail Pomacea Insularum, Veena Ramakrishnan
Earth & Environmental Sciences Dissertations - Archive
Pomacea insularum is a tropical and subtropical, ampullariid, freshwater prosobranch snail that is native to slow-flowing rivers and canals in South America. It is a member of the genus, Pomacea, and, like other species in this genus, can be a severe agricultural pest in wetland rice and taro agriculture systems. It has been introduced to the United States, establishing populations in the rice belt region of southeastern Texas. The resistance adaptations of P. insularum were investigated with respect to important physico-chemical parameters including temperature, salinity, pH, emersion, desiccation and progressive hypoxia in order to predict its potential distribution in North …
Hydrogeochemical Evolution Of Arsenic Along Groundwater Flow Paths: Linking Aqueous And Solid Phase Arsenic Speciation, Shama Haque
Earth & Environmental Sciences Dissertations - Archive
The central hypothesis of this Doctoral research work is that changes occurring along groundwater flow paths that accompany chemical weathering and oxidation-reduction reactions catalyze both arsenic (As) mobilization from, and capture by, minerals via adsorption/desorption and/or mineral dissolution/precipitation reactions. This central hypothesis is addressed by (i) quantifying concentrations and speciation of As, and ancillary geochemical parameters, including a number of redox sensitive parameters in groundwater samples collected along flow paths, and (ii) determining solid phase speciation of As in aquifer sediment samples, with specific emphasis on the labile (i.e., surface exchangeable) and non-labile As fractions (e.g., precipitated with Fe oxides). …
The Formation And Obduction Of Ophiolites Since The Late Precambrian, Stacey Metzler
The Formation And Obduction Of Ophiolites Since The Late Precambrian, Stacey Metzler
Earth & Environmental Sciences Theses - Archive
Ophiolite formation and emplacement has been episodic since the Late Precambrian. This research study examines ophiolites that formed during the Cenozoic, Mesozoic, Paleozoic and Late Precambrian. The ophiolites were plotted on paleogeographic reconstructions using PALEOMAP Project maps, and the ophiolite localities were analyzed by their temporal distribution in relation to the tectonic framework in which they were emplaced. The ophiolites appear to show episodic events linked to global plate reorganization. These episodes coincide with collisional events from the supercontinents of Gondwana and Pangea. The primary mechanisms of formation and emplacement proved to be mid-ocean ridge systems and back arc basins …
Selenium Speciation Along A Groundwater Flow Path In The Carrizo Aquifer, Southeastern Texas, Usa, Rituparna Basu
Selenium Speciation Along A Groundwater Flow Path In The Carrizo Aquifer, Southeastern Texas, Usa, Rituparna Basu
Earth & Environmental Sciences Theses - Archive
Selenium concentration and speciation [Se (VI), Se (IV) and Se (-II)] was determined along a flow path in the Carrizo Sand aquifer (southeastern Texas). Groundwater sampling was carried out in March 2006, from ten wells located along the flow path. The collected samples were filtered through 0.45 µm filters and then acidified to pH <2 using ultra pure HCl. Analysis for Se concentration and speciation was done using selective hydride generation>- Atomic Absorption spectrometry (HG-AAS). Additional in situ measurements from each well included determination of pH, alkalinity, oxidation-reduction potential (Eh in mV), dissolved iron speciation, dissolved sulfide concentrations and dissolved manganese concentrations. Selenium concentrations in groundwaters of the Carrizo Sand aquifer are very low (i.e., nanomolal …
Statistical Analysis Of Rock Fabrics, Boris Avdeev
Statistical Analysis Of Rock Fabrics, Boris Avdeev
Earth & Environmental Sciences Theses - Archive
The main goal of the work is to present new procedures for statistical analysis of fabric data for structural geology. After an introduction to the problems of orientation analysis, discussion of different types of the orientation data and a brief review of the existing techniques and statistics for the orientation data, a comprehensive discussion of several proposed methods is given. The first part of the methodology chapter states a general model in terms of a structural frame and introduces some notation. The second part is a detailed description of a pooled estimator, which is intended to assess a structural frame …
Alluvial Fan Deposits Of The Todos Santos Formation Of Central Chiapas, Mexico, Terence Cletus Blair
Alluvial Fan Deposits Of The Todos Santos Formation Of Central Chiapas, Mexico, Terence Cletus Blair
Earth & Environmental Sciences Theses - Archive
The Todos Santos Formation at Jerico was deposited as an alluvial fan system by high gradient, short duration ephemeral streams which transported gravel, sand, and mud northeastward through a feeder canyon which opened out onto an alluvial plain. This alluvial fan system is composed of streamflood, debris flow, and braided stream deposits. Three distinct alluvial fan environments were distinguished at Jerico: proximal fan facies, mid-fan facies, and distal fan facies. Analysis of the vertical succession of these depositional facies reveals two proximal to distal alluvial fan transitions separated by a distal to proximal transition. This suggests that a period of …
Alluvial Fan Deposits Of The Todos Santos Formation Of Central Chiapas, Mexico, Terence Cletus Blair
Alluvial Fan Deposits Of The Todos Santos Formation Of Central Chiapas, Mexico, Terence Cletus Blair
Earth & Environmental Sciences Theses - Archive
The Todos Santos Formation at Jerico was deposited as an alluvial fan system by high gradient, short duration ephemeral streams which transported gravel, sand, and mud northeastward through a feeder canyon which opened out onto an alluvial plain. This alluvial fan system is composed of streamflood, debris flow, and braided stream deposits. Three distinct alluvial fan environments were distinguished at Jerico: proximal fan facies, mid-fan facies, and distal fan facies. Analysis of the vertical succession of these depositional facies reveals two proximal to distal alluvial fan transitions separated by a distal to proximal transition. This suggests that a period of …