<p>The origin of the Sierra Quemada structure, located near the center of Big Bend National Park in Texas, has long been debated. It was originally described as a large igneous pluton by Maxwell et al. (1967) and later as a caldera by publications from Barker et al. (1986), Henry et al. (1986), and Duex et al. (1994). However, more recent publications from the United States Geological Survey (USGS) from Scott et al. (2007) and Page et al. (2008) interpreted the Sierra Quemada structure as a failed caldera without associated collapse. The main objective of this thesis is to investigate relationships between units from outside of the Sierra Quemada structure and units from inside of it by determining the geochemical composition of each sample through X-ray Fluorescence (XRF) analyses. XRF analyses were performed on over thirty samples collected from both inside (I) and outside (O) of the Sierra Quemada, including members of the Chisos Formation such as the Ash Spring Basalt (Tasb), the Bee Mountain Basalt (Tbmb), the Mule Ear Spring Tuff (Tmet), and the Tule Mountain Trachyandesite (Ttmt) as well as ring fracture intrusions (RF), ash flow tuffs (AFT), lithic rich tuffs (LRT), and Chisos Undifferentiated (Tchu). The results of the analyses were plotted on Harker Variation Diagrams that compare SiO2 concentrations to other major elements and oxides that are common in igneous rocks, such as Al2O3, K2O, FeO, Fe2O3, MnO, CaO, TiO2, MgO, and Zr. Harker Variation Diagrams are used to investigate genetic relationships between samples. Some of the diagrams show strong correlations between samples that are suspected to be related, but others show somewhat weaker relationships. These variable results could be attributed to analytical uncertainties from the XRF which are common for elements with atomic numbers (Z) lower than 14 or to variations in lithologic compositions among samples.

<p>The Coyote Mountains is a metamorphic core complex that makes up the northern end of the 80-km long Baboquivari Mountain complex. The Baboquivari Mountain complex is composed of Mesozoic rocks, Cenozoic granites, pegmatites, and metasediments (Wright and Haxel, 1982; Haxel et al., 1980, 1984). In the Coyote Mountains, there is an intrusion of the Pan Tak granite, a muscovite-biotite-garnet peraluminous granite dated at 58 Ma based on U-Pb analysis of zircon. The Pan Tak and other intrusions within the Baboquivari Mountains have been interpreted as anatectics melts representing the culmination of a Laramide crustal shortening orogenic event that started in the Late Cretaceous, about ~70 mya (Goodwin and Haxel, 1990). However, field evidence, as well as petrographic and microstructural analyses of metamorphic and deformational fabrics/structures show that the ~58 mya intrusive/magmatic fabric is overprinted by a secondary tectonic event. This event is particularly well recorded in the northern part of the Coyote Mountains, where a northdipping mylonitic shear zone is exposed. This study focuses on the Pan Tak granite with twenty samples from the northern portion of the Coyote Mountains, directly north of Coyote Peak, from the mapped areas of granites and mylonites.

<p> This study investigates the relationship between faulting, subsidence, and land loss in coastal Louisiana. A methodology that integrates 3D seismic data, well logs, high-resolution topographic mapping (LIDAR), and historical aerial photography is successfully developed to identify fault-related geomorphic changes in southwestern Louisiana&rsquo;s Chenier Plain. Analysis of a 3D seismic survey and well logs reveals the presence of 10 normal faults that form an east-west graben in the middle of the study area. Well logs were used to further constrain the geometry of the faults. Shallow water well logs were used to map the faults at shallow depth, below the resolution of the seismic survey. Fault traces were extrapolated to the surface by maintaining constant dip, and projected on LIDAR data. Elevation profiles derived from the LIDAR were conducted across the different faults, and results show that there is a distinct difference between the upthrown and downthrown sides of the faults. Historical aerial photographs were used to investigate any change in geomorphology from 1953 to 2017 within the study area. Results reveal the occurrence of water bodies on the immediate downthrown sides of suspected fault traces. Our findings suggest that faulting influences and focuses areas where subsidence is happening and subsequent land loss may occur and detailed understanding of active shallow faulting in coastal area can be used to identify regions that are at risk of land loss.</p><p>

<p> The Upper Cretaceous Austin Chalk is a tremendous hydrocarbon reservoir. The Austin Chalk is partly self-sourced,but is primarily sourced by the underlying Eagle Ford Formation. There have been numerous studies investigating the fracture network in the Austin Chalk to understand hydrocarbon migration and maximize recovery. However, limited research has been conducted to investigate the natural fracture system of the Eagle Ford formation, and to constrain migration pathway to the overlying Austin Chalk. Such research would reveal hydrocarbons pathways through the Eagle Ford and into the Austin Chalk. </p><p> This study investigates the fracture system of the Eagle Ford Formation that potentially served as migration pathways for hydrocarbons to the overlying Austin Chalk. The geochemistry of fracture fill is used to constrain fluid composition and source, and condition and timing of fluid migration. This project focuses on outcrops along U.S. Highway 90 north of Del Rio, as well as various quarries near Del Rio, San Antonio, and Waco in order to characterize the natural fracture system of the Eagle Ford Formation. Thin sections of fracture fill were collected for microstructural analysis to constrain paleostress, and vein crack and sealing mechanism over time. Geochemistry of the vein fill, Rock-Eval, and X-ray fluorescence are analyzed to constrain fluid-rock interaction and hydrocarbon migration.</p><p>

<p> The Colorado Cheyenne 3D seismic survey in this thesis project is located in Cheyenne and Kiowa counties in eastern Colorado and features the Las Animas Arch. The scope of this project aims to expand the understanding of the processes and products of salt weld development. Throughout the survey, lateral variability of the Nippewalla strata within the Permian section is observed in both seismic and well data and generally is a result of dissolution of the Blaine or the dissolution of the Cedar Hills. </p><p> In this project, structural and stratigraphic elements were seismically mapped and interpreted with a focus on salt dissolution and welding. Overall, the characteristics of the dissolution in the strata covered by the 3D seismic survey of this study can be separated by a centrally-located dissolution front with the western half of the area having the lower Blaine halite removed by dissolution and the eastern half having the lower Blaine halite preserved. Dissolution of the upper Blaine halite is pervasive through the study area, especially within the western region due to remnant salt. </p><p> The eastern half of the survey is also affected by the dissolution within the Cedar Hills Formation. Unlike the Blaine, the amount of dissolution that occurs in the Cedar Hills seems fairly consistent, removing almost the complete formation or no dissolution at all. </p><p> This thesis is intended to serve as an initial investigation of the structural and stratigraphic relations due to dissolution of the Permian salts. Numerous additional questions remain beyond the scope of this thesis. </p><p>

<p> The Sabine Uplift has been called a "mobile block" that has experienced periods of uplift and subsidence. The formation of this area has been attributed to one main driving factor, compressional forces due to tectonics (Granata, 1963; Halbouty and Halbouty, 1982; Jackson and Laubach, 1988a, 1988b, 1991; Ewing, 2009; Sawyer et al., 1991; Adams, 2009; Nunn, 1990). With authors attributing the major episodes of uplift of this area to the Laramide Orogeny, approximately 70 to 80 million years ago (Ma), it marks the time of the end of the Cretaceous (approximately 65 Ma) as a major key to understanding the area. One hundred and seventy-six well logs located in East Texas were used to analyze the area known as the Sabine Uplift in order to pinpoint times of uplift. The major horizons studied are the top of the Midway Shale, the Cretaceous/Paleogene boundary, and the James Limestone. Structure contour maps were created from this data set to determine the present day topography of the formations. These contour maps were then used to create isochore maps to determine whether the Sabine was a positive or negative feature at the time, or if it showed no topography at all. Furthermore, the well log data were used to identify different facies throughout the area to help determine topography.</p><p>

<p> The tectonic history of the Gulf of Mexico Basin in northwestern Mississippi is poorly understood due to a lack of publicly available data and overlying Mesozoic sediments. Using an extensive set of geophysical data including: well data, potential field data, and 2-D seismic data, we define distinct zones of varying structural styles across the region and provide new insight into the tectonic evolution of the northern margin of the Gulf of Mexico. </p><p> The cratonal region is defined by the extent of Precambrian basement across the region and is characterized by an orthogonal set of normal faults related to Precambrian &ndash; Cambrian rifting and subsidence along the southern Paleozoic shelf margin. The, now, foreland basin is composed primarily of Cambrian-Devonian shelf carbonates and Carboniferous clastics deposited along the southern continental margin, coinciding with the southern limit of Precambrian cratonal material. </p><p> Divisible into two structural domains, the Frontal and Allochthonous Domain, the sub-cropping Ouachita orogenic belt is defined by geophysical data in northwestern Mississippi. The Frontal Domain of the Ouachita zone is restricted to the western study area and is characterized by small, imbricate thrusts branching from a lower detachment within autochthonous sediments and an upper detachment along the base of back thrusted Carboniferous sediments. Large thrust sheets of the Allochthonous Domain are correlatable across the study area and are truncated to the north by large intrusions or basement blocks. </p><p> The seismically defined limit of the basinal zone corresponds to a linear gravity minima separating Mesozoic rift-related basins to the south from Precambrian and intrusive bodies to the north. Geophysical data of the basinal zone characterize multiple igneous bodies of varying ages. Syn-rift Triassic graben clastics confined to grabens paralleling the basinal zone limit are interpreted to be related to a Mesozoic rift-related transform across Mississippi separating rift basins of the larger region.</p><p>

<p> The Upper Cretaceous Austin Chalk Formation has been a prolific oil and gas producer in Louisiana, with cumulative production greater than 57 million barrels of oil (MMBO) and 246 billion cubic feet (BCF) of gas. Production was previously limited to areas containing natural fractures that provided permeability to the formation. Recently, there has been interest in fracture stimulating the formation in order to produce hydrocarbons from new areas. In this study we evaluated the Austin Chalk Formation as a potential reservoir for hydrocarbons and attempted to locate areas with the greatest production potential within our study area. We used available well logs across Louisiana to map rock properties associated with potential hydrocarbon production. Log measurements from 116 wells were used to create maps of structure, thickness, resistivity, water saturation, and porosity. Historical production and mud weights were used to map oil, gas, and water production as well as estimated pore pressure. From these maps, we generated composite maps of hydrocarbon-foot and original oil in place, as well as a composite risk map. The risk map was based on the primary components of oil in place: thickness, porosity, and water saturation. The thickness was greater in the eastern portion of the study area than the western portion. We also found that porosity was greatest in the southern, deeper portion of the study area. Water saturation followed an arcuate trend and was found to be the highest in the northern portion of the study area and lowest in the central portion of the study area. The composite risk map illustrates three areas with high likelihood for hydrocarbon production, one of which correlates to past production. We conclude that these mapped areas with significant thickness, high porosity, and low water saturation have the lowest risk and the greatest production potential.</p><p>

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Geology, 1933. / Includes bibliographical references (leaves 175-178). / by Katharine W. Carman. / Ph.D.

Thesis. (M.S.) Massachusetts Institute of Technology. Dept. of Geology, 1947. / Bibliography: leaves 119-121. / by Gilbert Englander Klein. / M.S.