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Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
Lateral distribution of detrital clay minerals in Lower Cretaceous sediment, western North Atlantic and its continental margin
Description:
Fine grained sediment from Lower Cretaceous turbidites (DSDP Site 603) and their correlative deltaic deposits (Baltimore Canyon Trough) were compared mineralogically and texturally. The shelf sediment is coarser grained than deep sea... In deep-sea turbidites, smectite dominates the $<$0.5 micrometer fraction and illite is most abundant in coarser clay fractions. Smectite level is highest in clay-rich sand beds and in clay rip-up clasts, indicating it has been reworked... Previous studies of the clay mineral composition of Lower Cretaceous western North Atlantic sediment hypothesized extensive vertisols along the eastern North American margin to account for high smectite levels, but the results of this... Possible sources for pelagic smectite include Early Cretaceous volcanic ash derived from the New England-Quebec volcanic event, from andesitic volcanism in Mexico, and possibly more extensive exposure of syn-rift diabase and associated...
To better constrain the timing of panda's dietary shift from omnivorous to bamboo-exclusive herbivores, this study analyzed stable isotopes of carbon and oxygen in tooth enamel samples from two pygmy pandas from Yanliang Cave (early...
The Abbotsford 7.5’ quadrangle resides entirely within the Dadeville complex, a volcanic arc complex located in the Alabama-Georgia Inner Piedmont region of the southern Appalachian mountain belt system. The Dadeville complex has been...
Two major thrust systems are located along the eastern Blue Ridge â western Blue Ridge boundary in the Alabama and Georgia Appalachians. The pre-metamorphic Hillabee thrust is near the trailing edge of the Talladega belt thrust sheet...
GEOCHEMISTRY, MINERALOGY AND ORIGIN OF MESOZOIC DIABASE DIKES OF VIRGINIA
Description:
Mesozoic diabase dikes of Virginia, part of the Eastern North America dike swarm, display a wide variety of mineralogical and chemical characteristics, representative of most mineralogical and chemical groups described from other... Petrographically, the diabases can be classified into three groups, which also display some geochemical distinctions. The OSB group is characterized by abundant olivine as a phenocryst and/or groundmass component and the presence of a Cr... Major- and compatible trace-element geochemical trends show that typical SGA-group samples can be derived by crystallization of approximately 17-20% olivine with minor spinel from a magma similar in composition to primitive OSB-group... OSB-group samples with compositions that are primitive with respect to major- and compatible trace-element chemistries display a wide and continuous range of incompatible trace-element (ITE) contents and ratios. While some of this...
Late Quaternary Evolution of the Northwest Florida Coast and Margin: Development of a Conceptual Model for Identifying and Characterizing Shelf Sediment Deposits
The objective of this investigation was the interpretation of the late Quaternary history of the northwest Florida margin and the development of a conceptual model for understanding the late Quaternary evolution of the regional coast and...
Quantifying the Effects of Increased Storminess and Sea-Level Change on the Morphology of Sandy Barrier Islands along the Northwestern and Atlantic Coasts of Florida
The ability to accurately quantify shoreline variability along sandy beaches is essential in order to establish aggressive mitigation strategies, based on recent global climate change projections. This investigation employed a suite of...
MINERALOGY, GEOCHEMISTRY AND RADIOACTIVITY OF SOME EGYPTIAN PHOSPHORITE DEPOSITS
Description:
Mineralogical, geochemical, and radiogeological studies of forty nine phosphorite samples from three main mining areas in Egypt, Abu Tartur (Western Desert), Sibaiya (Nile Valley), and Safaga (Red Sea) have been carried out and the... X-ray diffraction studies of these Egyptian phosphorites show that carbonate-fluorapatite (francolite) is the major phosphorite mineral in these deposits, with partial substitution of Mg and Na for Ca, and (CO(, 3)) for (PO(, 4)). Other... The uranium content and U/P(, 2)O(, 5) ratio show low values in Abu Tartur phosphorite deposits relative to the Red Sea and Nile Valley deposits. Autoradiographic studies of the Egyptian phosphorites showed that the radioactivity is... Geochemically, four distinct groups of minerals were identified in the Egyptian phosphorites according to the degree of correlation between the major apatite components and the trace elements. These mineral groups are apatite, clays, ...
Calcareous Nannoplankton as Paleoceanographic and Biostratigraphic Proxies: Examples from the Mid-Cretaceous Equatorial Atlantic (ODP Leg 207) and Pleistocene of the Antarctic Peninsula (NBP0602A) and North Atlantic (IODP Exp. 306)
This dissertation is a collection of three projects utilizing calcareous nannoplankton as biostratigraphic and paleoceanographic indicators. The materials studied come from three locations: 1) Ocean Drilling Program (ODP) Leg 207 (Site...
Pre-Haynesville stratigraphy and structural geology of the Apalachicola Embayment: petrology and paleoenvironmental interpretation of the Smackover Formation
Investigation of Changes in Paleoceanographic Redox State as a Driver for Early Silurian Extinction Events Using Multiple Geochemical Proxies in the Baltic Basin
Two mudstone-dominated early Silurian drill cores from the Baltic Basin were analyzed for pyrite sulfur isotopes (δ34Spy), organic matter carbon isotopes (δ13Corg), as well as iron speciation and trace metal chemostratigraphy to...
THE LITHOSTRATIGRAPHY OF THE HAWTHORN GROUP (MIOCENE) OF FLORIDA (PHOSPHATE, PHOSPHOGENESIS, PHOSPHORITE, FLORIDA, GEORGIA)
Description:
The Hawthorn Formation of previous investigators has been raised to group status in Georgia. The present investigation extends the formations recognized in southern Georgia into northern Florida with some modifications. The Hawthorn... The Hawthorn Group in northern Florida consists of, in ascending order, the Penney Farms, the Marks Head and the Coosawhatchie formations. The Coosawhatchie Formation grades laterally and, in a limited area, vertically into the... Lithologically, the Hawthorn Group in northern Florida is made up of a basal carbonate with interbedded clastics (Penney Farms), a clastic-carbonate sequence (Marks Head), a predominantly clastic unit (Coosawhatchie) and a crossbedded, ... In southern Florida the group is comprised of two formations (in ascending order) the Arcadia and the Peace River. The Tampa Formation of former usuage is included as a lower member of the Arcadia Formation. Similarly, the Bone Valley... Lithologically the Arcadia Formation is composed of carbonate with varying amounts of clastics. Clastic sediments in the Arcadia are most prevalent in the Nocatee Member (basal Arcadia). The Peace River Formation is predominantly a... The Hawthorn Group in the eastern Florida panhandle is composed of the Torreya Formation and in a few areas a Middle (?) Miocene unnamed clastic unit. Lithologically, the Torreya consists of a carbonate rich basal section and a...
AN INVESTIGATION OF THE GEOLOGY, HYDROGEOLOGY, AND HYDROCHEMISTRY OF THE LOWER SUWANNEE RIVER BASIN (FLORIDA)
Description:
The purpose of this study was to conduct a unified comprehensive investigation of the hydrogeology of a basin located in a carbonate terrain. This study defines the geologic and hydrogeologic characteristics of the Lower Suwannee River... All of the area within the Lower Suwannee River Basin is underlain by limestones and dolomites; most of these deposits lie near the surface. Solution of the carbonates has resulted in the development of a karst plain. Examination of 222... Utilizing R-mode factor analysis and correlation coefficient analyses, it was possible to distinguish water samples from wells completed into a surficial aquifer from those completed into the Floridan aquifer. Three water masses were... Analyses for uranium were performed on water samples from 62 wells, 32 springs, and 5 river sites. Factor analysis showed an inverse relationship between the U-238 concentration and the U-234/U-238 activity ratio; however, the uranium... The activity ratios for wells and springs ranged from .39 (+OR-) .02 to 2.57 (+OR-) .60. The uranium concentrations range from less than .02 ppb to 44.8 (+OR-) .11 ppb. Generally, high ratio-low concentration values are associated with... The Lower Suwannee River is almost totally dependent on groundwater contributions for its flow. Both river hydrochemical data and the uranium disequilibrium results supported this conclusion.
The thesis presents and evaluates five new gravity constrained structural cross-sections about the Palos Verdes and Cabrillo faults of southern California. They both have been active since the Miocene, however the Palos Verdes fault zone...
Reconstruction of the supratidal history of St. Joseph peninsula was approached on a granulometric, geometric, and internal-structure basis. Textural and geomorphic evidences supports the hypothesis that the peninsula was integrated from two former barrier islands through subtidal aggradation as well as seaward and lateral progradation. The granulometric characteristics of... Salinity-biotopes from benthic foraminifera in the sampled core connote a gradual sea level rise accompanying platform aggradation in the Late Holocene. The terminal stages of this sea level rise were characterized by small-scale... The pre-Holocene topography suggests that the Cape San Blas area represents the site of the earliest stages of platform aggradation. The oldest areas on the spit appear to have emerged at least 1, 500 years ago. The Cape San Blas tombolo... Two sediment sources were inferred from this study: Cape San Blas and Bell shoal. Transverse transport was more important earlier in the history of the spit, but littoral drift later became dominant. North of Eagle Harbor, the spit developed under decreasing wave energy conditions. Beach ridge origin on St. Joseph spit based on internal structure alone is equivocal. Both eolian and non-eolian strata were observed although the latter were more widespread. Certain previous work has also shown the internal structure of ridges can form by vegetative trapping. On the backshore of prograding beaches where the subaerial stages of beach ridge history begins, eolian and swash strata are inseparable. Beach ridges are therefore considered to be examples of convergent landforms, evolving initially... Some of the eolian traits appear to come from pulses of eolian settling of "dust" as indicated by the tail-of-fines. The standard deviation and the tail-of-fines were the most diagnostic criteria recognizing eolian traits. In general, sediment in the study area revealed an environmental succession from fluvial to beach and (finally) to dune.
Mobilization of the radionuclides radon, thorium and radium in groundwater by the alpha-recoil mechanism
Description:
Ion motions, involving atomic collisions within the solid and fluid phases are simulated using a three-dimensional Monte Carlo algorithm, which is based on the principles of ion scattering and electronic interactions with the moving ion.... demonstrate that the recoil effect does occur in a natural sample, and could cause radioactive depletion on the sample surface.
Oceanic core complexes (OCCs) are the uplifted and rotated footwalls of detachment faults formed at areas of slow spreading on mid-ocean ridges. Detachment faults initiate close to the spreading axis, and because it is easier to continue...
The Appalachian orogen is separated from west to east and into the Cumberland Plateau, Valley and Ridge, Blue Ridge, Inner Piedmont, and Carolina Superterrane physiographic provinces. Within the southern Appalachians of Alabama and...
The southeastern Blue Ridge hosts a suite of metamorphic rock units that provide insight to the Neoproterozoic to Paleozoic tectonic influences that impacted the Laurentian continent. The Ashland-Wedowee-Emuckfaw belt of the southernmost...
The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of...
Until the past decade, IIAB iron meteorites were thought to have formed by fractional crystallization under low pressure, corresponding to an asteroidal sized (<200 km) parent body. Some recent physical models for the formation of early...
Salt marshes provide an important habitat for animals and food for fish, shellfish, birds and mammals. They also serve as a breeding ground and nursery for numerous species. The value of salt marshes lies in the benefits that it provides...
PALEOGENE ABYSSAL ENVIRONMENTS OF THE EASTERN SOUTH ATLANTIC: A FORAMINIFERAL STUDY
Description:
Paleogene abyssal environments in the eastern South Atlantic were analyzed with respect to stable isotopes, population dynamics, and patterns of dissolution. Combined results of these studies indicate three times of change in the abyssal... An extinction event occurred at the end of the Paleocene which removed many species from the benthic foraminiferal population. This event was cosmopolitan and may have been the result of altered circulation patterns due to the separation... In the middle Eocene the benthic fauna oscillated between opportunist taxa typical of the early Paleogene and generalist species which were dominant in the late Eocene. The middle Eocene shifts in assemblage components appear to be due... A decisive shift from opportunist taxa toward a generalist assemblage occurs in the late Eocene. Species originations are high in the late Eocene which results in high species diversity prior to the Eocene-Oligocene boundary. In the... An additional shift in ('18)O values occurred at the Eocene-Oligocene boundary indicating a temperature drop of 4(DEGREES)C. This may be a result of the full development of a psychrospheric ocean and initiation of intensification of AABW... Dissolution studies suggest high CCD and lysocline positions for the late Eocene and Miocene. The Oligocene CCD is depressed possibly due to increased productivity in a well mixed ocean.
The Panamanian Isthmus presents an ideal opportunity to study arc magmatism, arc-hotspot interaction, and the effects of the South America-Panama collision. These effects include changing mantle wedge compositions and localized tectonic...
In this study, a laboratory analog is used to simulate the conduit and matrix domains of a Karst aquifer. The conduit domain is located at the bottom of the transparent plexiglas laboratory analog and glass beads occupy the remaining...
A Study of the Lithological and Petrographical Changes Across the Eocene-Oligocene Transition of the Ocala and Suwannee Formations in Northern Florida and Southern Georiga
With so few Eocene outcrops throughout Florida, it is difficult to study the Eocene-Oligocene boundary between the Ocala and Suwannee Limestone. This study provides a more detailed lithological description of the differences of rocks on...
Biometric analysis of Eocene and Oligocene calcareous nannofossils
Description:
Four Eocene to Oligocene calcareous nannofossil species groups were analyzed biometrically from DSDP and ODP Sites 366, 549, 558, 563, 628, 647, and 748. Integrated biostratigraphic and magnetostratigraphic data established the age of... Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA) of Cyclicargolithus shows that no significant differences in shape occur with changes in size, age, or latitude. Size increases are asynchronous between sites, ... Development of a large sized (mean $>$11 um) population of the Reticulofenestra umbilica/R. hillae group occurred between 45.0 and 42.8 Ma in three sites. The first occurrence of specimens $>$14 um in size is highly asynchronous and not... Principal Components Analysis of the Reticulofenestra bisecta complex revealed an overall gradual size increase from middle Eocene to Oligocene, and a rapid increase in hole size beginning in early Oligocene in high latitudes. R. bisecta... Principal Components Analysis of the Chiasmolithus expansus/C. oamaruensis/C. altus lineage revealed large fluctuations in the width of the central 'X' structure from upper middle Eocene to Oligocene, possibly related to changes in water...
The timing and mechanisms responsible for the expansion of C4 grasses have been a topic of considerable debate over the last two decades. Although abundant evidence indicates that there was a worldwide, rapid increase in C4 ecosystems ...
The Greenland Ice Sheet (GrIS) is melting at an alarming rate. Supraglacial melt water flows into moulins that drain to the base of the ice sheet, and enhances basal flow. Ultimately, large quantities of melt water are expelled into the...
There are no published quantitative studies of coccolithophore standing crops in the North East Gulf of Mexico (NE GOM). When the Macondo oil spill happened in April of 2010 researchers scrambled to determine what effect it would have on...
The overall goal of this project is to better understand geologic characteristics of the Raton Basin. The Raton Basin is a Rocky Mountain foreland basin that contains Pennsylvanian through modern sedimentary rocks. The current structure...
This project seeks to determine how the opening of the Red Sea rift was influenced by pre-existing tectonic features and to place constraints on the structural evolution of the western Saudi Arabia margin. In detail, we investigate...
Investigation of Paleoredox Conditions across the Llandovery- Wenlock (Silurian) Boundary: Implications for the Ireviken Extinction Event and Carbon Isotope Excursion
The Ireviken extinction event occurred within the early-middle Silurian, spanning the Llandovery-Wenlock boundary, ~431 million years ago and has been proposed to have been initiated at least partly through the transition from late...
BIOSTRATIGRAPHY OF THE HAWTHORN FORMATION IN NORTHEAST AND NORTH CENTRAL FLORIDA
Description:
Cores recently drilled along Florida's east coast by the Florida Bureau of Geology have yielded a record of the most complete Florida Hawthorn fossiliferous sediments heretofore available for biostratigraphic analysis. The record of... A diversity of microfossil groups including diatoms, silicoflagellates, foraminifera and coccoliths were identified in the Hawthorn sediments. Diatoms, which represented the largest and most definitive number of species, were the primary... The occurrence of an upwelling diatom assemblage in Hawthorn sediments of four northern cores is believed to be the result of coastal upwelling and/or influx from a postulated offshore cool water current during Middle Miocene time....
This dissertation employs chemical analysis as a tool to explore past environments and processes, and to examine the viability of matrix-independent standardization of laser ablation inductively coupled plasma mass spectrometry. The...
The submarine equilibrium profile: A physical model
Description:
The concept of the submarine equilibrium profile has long been established. This dissertation first proposes a conceptual model based on the well established concept. Then it proposes an analytical model with a differential equation which is based on the Airy wave theory and the wave-induced asymmetrical onshore... A "SIMPLEX" non-linear regression algorithm was used to write a computer program "SIMPYA" in GWBASIC. The computer program approaches two unknown parameters in the equation using sample profile data plotted on some coasts around... A wave tank, a wave generator and an adjustable platform were designed and constructed by the author, and were used in an effort to verify the analytical model. The unique platform provides independently adjustable settings of slope and... The Application of the model may include assessment of profile stability, profile evolutionary trends, development of transitional models and coastal engineering calculations.
The Oligocene-Miocene collision between Panama and South America significantly influenced ocean currents, global climate, and species diversification. Intraplate deformation of the Panama Block also played an important role in the...
The southern Appalachian Inner Piedmont in east central Alabama and west Georgia consists of two tectonically separated Ordovician lithotectonic units: the structurally upper Dadeville Complex and the underlying Opelika Group. The...
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