Geology Commons^™

The Search For The Missing Mantles Of Differentiated Asteroids: Evidence From Taxonomic A-Class Asteroids And Olivine-Dominated Achondrite Meteorites, Michael Peter Lucas

USF Tampa Graduate Theses and Dissertations

The apparent rarity of taxonomic A-class asteroids poses a significant paradox for understanding asteroid differentiation and the dynamical evolution of the early solar system. Based on results from asteroid taxonomic surveys, and on the abundances and mineralogy of different achondrite meteorites, it appears that olivine-dominated mantle remnants are missing from both the asteroid population and in meteorite collections. Several scenarios to explain this paradox have been proposed: (1) olivine mantle material has been stripped away by collisions and only remains as small fragments (< ~5 km), (2) A-class asteroids are abundant but have been altered in some way masking their presence, or (3) differentiated asteroids did not form thick olivine-rich mantles.

We have approached these questions through the collection of taxonomic and observational data on known A-class …

Impacts Of Artificial Reefs On Surrounding Ecosystems, Sarine Manoukian

USF Tampa Graduate Theses and Dissertations

Artificial reefs are becoming a popular biological and management component in shallow water environments characterized by soft seabed, representing both important marine habitats and tools to manage coastal fisheries and resources. An artificial reef in the marine environment acts as an open system with exchange of material and energy, altering the physical and biological characteristics of the surrounding area. Reef stability will depend on the balance of scour, settlement, and burial resulting from ocean conditions over time. Because of the unstable nature of sediments, they require a detailed and systematic investigation.

Acoustic systems like high-frequency multibeam sonar are efficient tools …

Seasonal Changes In The Sinking Particulate Flux And In The Nitrogen Cycle Within The Euphotic And Twilight Zones Of The Cariaco Basin, Venezuela, Enrique Montes-Herrera

USF Tampa Graduate Theses and Dissertations

This study explored the effects of seasonal variability on the geochemistry of sinking pthesiss and on the nitrogen cycle of the Cariaco Basin. Pthesis fluxes were measured at the base of the euphotic zone (the depth of 1% of photosynthetically active radiation - PAR) with drifting sediment traps during months of upwelling and non-upwelling regimes from March 2007 to November 2009. Flux estimates were analyzed in the context of seasonal variations in sea surface temperature, primary productivity, and chlorophyll a concentrations using data generated by the CARIACO Time-series Program as well as satellite data. Additionally, nine years (1996-2000 and 2004-2007) …

Evidence From The Florida Straits For Younger Dryas Ocean Circulation Changes, Jean Lynch-Stieglitz, Matthew W. Schmidt, William B. Curry

OES Faculty Publications

The waters passing through the Florida Straits today reflect both the western portion of the wind-driven subtropical gyre and the northward flow of the upper waters which cross the equator, compensating North Atlantic Deep Water export as part of the large-scale Atlantic meridional overturning circulation. It has been postulated from various lines of evidence that the overturning circulation was weaker during the Younger Dryas cold event of the last deglaciation. We show here that the contrast in the oxygen isotopic composition of benthic foraminiferal tests across the Florida Current is reduced during the Younger Dryas. This most likely reflects a …

Meridional Shifts In The Marine Itcz And The Tropical Hydrologic Cycle Over The Last Three Glacial Cycles, Matthew W. Schmidt, Howard J. Spero

OES Faculty Publications

Paleoproxy studies show a strong correlation between tropical climate and high-latitude temperature variability recorded in the Greenland ice cores over the last glacial cycle. In particular, abrupt cooling events in the Greenland Ice Sheet Project II δ¹⁸O ice record appear synchronous with a southward migration of the Intertropical Convergence Zone (ITCZ) in the Atlantic, a weakening of the Indian and East Asian monsoon systems, and a strengthening of the South American monsoon system. Because this high-to-low-latitude climate teleconnection significantly alters the tropical hydrologic cycle around the globe, it plays a critical role in regulating global climate on glacial-interglacial …

Florida Straits Deglacial Temperature And Salinity Change: Implications For Tropical Hydrologic Cycle Variability During The Younger Dryas, Matthew W. Schmidt, Jean Lynch-Stieglitz

OES Faculty Publications

The prevailing paradigm of abrupt climate change holds that rapid shifts associated with the most extreme climate swings of the last glacial cycle were forced by changes in the strength and northward extension of Atlantic Meridional Overturning Circulation (AMOC), resulting in an abrupt reorganization of atmospheric circulation patterns with global teleconnections. To determine the timing of tropical Atlantic atmospheric circulation changes over the past 21 ka BP, we reconstruct high resolution sea surface temperature and δ¹⁸O_SW (a proxy for surface salinity) records based on Mg/Ca ratios and oxygen isotope measurements in the planktonic foraminifera Globigerinoides ruber from …

Structural Evolution Of An Intracratonic Rift System; Mississippi Valley Graben, Rough Creek Graben, And Rome Trough Of Kentucky, Usa, John Bibb Hickman Jr.

University of Kentucky Doctoral Dissertations

As indicated by drilling and geophysical data, the Mississippi Valley Graben, the Rough Creek Graben, together with the Rome Trough of eastern Kentucky and West Virginia, are fault-bounded graben structures filled with as much as 27,000 feet of Early to Middle Cambrian sediments. Detailed regional mapping of Cambrian and younger strata within and surrounding these structures indicates that they formed contemporaneously. The proximity of these structures suggests they developed within the same regional stress fields and tectonic environments. These three structures are mechanically and kinematically connected, and formed part of a single continent-scale rift system produced during the breakup of …

Petrologic, Geochemical, And Geochronologic Constraints On The Tectonic Evolution Of The Southern Appalachian Orogen, Blue Ridge Province Of Western North Carolina, Eric Douglas Anderson

University of Kentucky Doctoral Dissertations

The Blue Ridge Province of western North Carolina contains a wide variety of metamorphosed igneous and sedimentary rocks that record the tectonic effects of Precambrian and Paleozoic orogenic cycles. Tectonic interpretations of the events that led to the present configuration are varied and often conflicting. This investigation examines metamorphosed mafic rocks that are widely interpreted to have formed during the closure of ocean basins. Metabasites, and specifically eclogites, have a tendency to mark tectonic sutures and frequently preserve pressure (P), temperature (T), and age data (t) that can be gleaned from mineral equilibria and U-Pb isotopic compositions. As such, the …

Crustal Structure And Evolution Beneath The Colorado Plateau And The Southern Basin And Range Province, Lamuail Bashir

Doctoral Dissertations

"Stacking of about 15,500 P-to-S receiver functions recorded at 72 USArray and other broadband seismic stations placed on the Colorado Plateau and the SBRP in Arizona revealed systematic spatial variations in crustal Vp/Vs, crustal thickness and amplitude of P-to-S converted phases. Our results reveal that the BRP is characterized by a thin crust (28.2 ± 0.5 km), a mean Vp/Vs of 1.761 ± 0.014 and a mean amplitude (R) of P - to - S converted wave (relative to that of the direct P wave) of 0.181 ± 0.014 that are similar to a typical continental crust, consistent with the …

Using Temperature Profiles To Investigate The Hyporheic Zone In An Agricultural Drainage Ditch, Richard A. Suggs

Theses and Dissertations

During the last three decades, there has been much research on ground water/surface water interaction and hyporheic zone processes in natural rivers and streams. Research into natural systems has revealed significant ground water/surface water interaction and a complex variability that depends primarily on surface conditions, subsurface composition, and seasonal influences. Hyporheic zone interaction is an important factor contributing to water quality of both surface water and ground water systems.

This research expands on the concept of using heat transport, as revealed by temperature variation, as an analogue for water movement within a surface water/ground water system to include the man-made …

Seismic Interpretation And Reservoir Characterization Of The Middle Eocene Gialo Formation, Assamoud Field, Sirte Basin, Libya, Abdalla Abdelnabi

Masters Theses

"The Gialo Formation is a major gas producing reservoir in the Assamoud Field, Sirte Basin, Libya. It is called Gialo limestone because it consists of shallow marine limestone. Seismic and well data in conjunction with the results of a previous study were used to delineate the hydrocarbon reservoir of Middle Eocene Gialo Formation of Assamoud Field area located in Eastern part of concession 6, Sirte Basin, Libya. The data include three-dimensional seismic data acquired by Sirte Company in 2009. It covers approximately an area of 150 km² and with more than 10 wells penetrating the reservoir. Seismic data were used …

Geological And Geomorphological Evolution Of The Egyptian Nile Between Aswan And Kom Ombo: A Remote Sensing And Field Study Approach, Leslie Lansbery

Masters Theses

"This work uses field and remote sensing studies to examine structural controls of the Egyptian Nile between Aswan and Kom Ombo (referred here to as AKN). This segment of the Egyptian Nile incises through Cretaceous Nubian sandstone and Precambrian crystalline rocks separated by a shallowly-dipping to theN unconformity. It was only 0.8 Ma that the Egyptian Nile connected to the rest of the sub-Sahara Africa drainage system. Prior to this time, the Egyptian Nile evolved independently through 8 phases: Pre-Eonile (Ma), Eonile (6.0-5. 4 Ma), Gulf Phase (5.4-3.3 Ma), Paleonile Phase (3.3-1.8 Ma), Desert Phase (1.8-0.8 Ma), Prenile Phase (0.8-0.4 …

Morpho-Tectonic Analysis Of The Tekeze And The Blue Nile Drainage Systems Of Northwestern Ethiopian Plateau, Ethiopia, Elamin Hassan Dai Ismail

Masters Theses

"This study examines the morpho-tectonic evolution of the drainage system in the northwestern Ethiopian plateau by focusing on the Tekeze and the Blue Nile Rivers. The plateau is underlain by Precambrian crystalline rocks, overlain by Mesozoic sedimentary section that is topped with a 1-3 km thick pile of Oligocene-Quaternary volcanic rocks. It is bounded in the east and southeast by the Afar Depression (AD) and the Main Ethiopian Rift (MER). Satellite derived Digital Elevation Models are analyzed using ArcGIS and RiverTools to extract morpho-tectonic parameters of tributaries of the Tekeze and Blue Nile Rivers including Normalized Steepness Index (K_{sn …}

The Origin Of Quartz Glomerocrysts: Insights From The Rhyolite Dike At Medicine Park, Ok, Sedeg Ahmed E. Ahmed

Masters Theses

"The origin of quartz glomerocrysts a distinctive petrographic feature of the rhyolite dike in Medicine Park, Oklahoma, was investigated using transmitted light and cathodoluminescence microscopy to determine if quartz glomerocrysts formed during quartz crystallization or during quartz dissolution. Quartz glomerocrysts are typically comprised of two to six individual phenocrysts of quartz and commonly exhibit subhedral partially embayed crystal forms with very rare euhedral phenocrysts in both glomerocrysts and individual quartz phenocrysts. The size range of the individual quartz phenocrysts are 0.08mm to 1.7mm while the size range is 0.08mm to 3.25mm for quartz glomerocrysts . Cathodoluminescence revealed that individual quartz …

Evaluating The Effectiveness Of Multi-Spectral Remote Sensing Data For Lithological Mapping In Arid Regions: A Quantitative Approach With Examples From The Makkah Neoproterozoic Region, Saudi Arabia, Nawwaf Awad Al Muntshry

Masters Theses

"This work quantitatively evaluates the effectiveness of multi-spectral remote sensing data for geological mapping in arid regions. For this, Landsat Thematic Mapper (TM) data covering part of the Neoproterozoic Arabian Shield around the Makkah region in Saudi Arabia are used. The Makkah region is dominated by a variety of layered and intrusive rocks covered by unconsolidated sediments. The Landsat TM data have six spectral bands in the visible and near infrared (VNIR) and shortwave infrared (SWIR) with thirty meters spatial resolution.

The Optimum Index Factor (OIF) has been computed to determine the best Red-Green-Blue (RGB) band combination emerging from the …

The Sorption Of Chemical And Nuclear Contaminants From Soil And Water Using Nanosize Particles Of Hydroxyapatite, Chyrene Joseph

Masters Theses

"High surface area (>200 m²/g) crystals composed of nanosize (30-50nm) hydroxyapatite; (Ca₅(PO₄)₃OH) particles are being investigated as an alternative in cleaing [sic] contaminated groundwater and soil by removing toxic wastes and radionuclides. Static batch tests were carried out at 2, 4, 8, 24 and 120 hour time periods by reacting hydroxyapatite with individual solutions prepared with specific elements to evaluate the applicability of hydroxyapatite in removing potential contaminants. Chemical analyses on leachant solutions, leachate solutions, and post-reaction digested solids were conducted by Inductively Coupled Plasma-Mass Spectroscopy to determine the extent of ion removal. Removal of these ions is expected …

A Detailed Petrographic Analysis Of The Mt. Sheridan Roosevelt Gabbro And Associated Rock Types, Daniel Russell Lasco

Masters Theses

"The Mt. Sheridan Roosevelt Gabbro of the Wichita Mountains igneous province in Southwestern Oklahoma underwent dynamic crystallization, resulting in three distinct gabbro zones with a range of pegmatite morphologies spread throughout. The three zones are informally named the lower, central, and upper zones. The lower zone consists of a quartz and alkali feldspar poor, plagioclase and pyroxene rich, poorly altered, gabbro cumulate. The central zone is comprised of a heavily altered quartz and alkali feldspar rich gabbro with few cumulate textures. The upper zone is mineralogically and texturally identical to the lower zone, distinguished only by its higher elevation. The …

Trace Element And Stable Isotope Data From A Flowstone In A Natural Cave Of The Mining District Of Sw Sardinia (Italy): Evidence For Zn²⁺-Induced Aragonite Precipitation In Comparatively Wet Climatic Conditions, Guglielmo Angelo Caddeo, Jo De Waele, Franco Frau, Loren Bruce Railsback

International Journal of Speleology

A speleothem from Crovassa Azzurra, a mine cave in SW Sardinia (Italy), has been analysed for mineralogy, minor and trace elements and stable isotopes. It is composed of layers of primary calcite and aragonite, with a region of secondary calcite. The primary carbonate is strikingly rich in Zn and Pb, presumably as the result of transport in solution from overlying Pb-Zn deposits. Immediately below the transition between calcite and aragonite, concentrations of Zn, Cd and P increase. At the transition between aragonite and Pb-rich aragonite, concentrations of Pb and P increase. Stable isotopes indicate an evolution toward more humid periods …

Minerals And Speleothems Of The József-Hegy Cave (Budapest, Hungary), Szabolcs Leél-Őssy, Gyöngyvér Szanyi, Gergely Surányi

International Journal of Speleology

With the discovery of the József-hegy Cave, a cave of hydrothermal origin with an abundance of minerals unknown so far in Hungary came to light. Diversity and the frequency of the occurrence of crystals make this cave similar to the Lechuguilla Cave, even if the dimensions of the mineral precipitations and the passages do not compare in scale. The variety and mass of carbonates and sulphates are surprising. This paper describes the minerals and speleothems of the József-hegy Cave, their occurrence and genesis, including determined ages. The 41 U/Th measurements suggest that speleothems begun to develop in the upper level …

Potential For Speciation In Mammals Following Vast, Late Miocene Volcanic Interruptions In The Pacific Northwest, Ryan Thomas Mckenna

Dissertations and Theses

The impact of large-scale volcanic eruptions on landscapes can affect many processes ranging from interrupting or redirecting regional soil forming processes and hydrological systems to generating temporary changes in global climate. Though more studies exist every year, less is known of the direct impact of large-scale volcanic eruptions on ecosystems and extinction, while even less is known of their impact on speciation. In deposits throughout the Pacific Northwest a special combination and association of volcanic magnitude with palaeoecological yield frequently presents unique prospects for inquiry. In this study, particular attention is given to large, late Miocene ash-flow tuffs of central …