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Articles 361 - 390 of 423

Full-Text Articles in Earth Sciences

Fluvial Evolution Of The Garonne River, France: Integrating Field Data With Numerical Simulations, Robin Rene Lancaster Jan 2005

Fluvial Evolution Of The Garonne River, France: Integrating Field Data With Numerical Simulations, Robin Rene Lancaster

LSU Master's Theses

The Garonne River of southwestern France presents a unique opportunity to study the controls on long-term incision and terrace formation within a large-scale fluvial system. The Garonne heads in the Pyrenees, flows through the Aquitaine Basin, and discharges into Atlantic Ocean via the Gironde Estuary/Bay of Biscay. From field data, three terrace complexes were identified and traced for >251 km from the base of the Pyrenees to the onset of tidal influences. Each complex is separated from adjacent complexes by scarps >10 m and represent 10s to 100s kyrs during which time the river occupied a finite elevational range within …

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Komatiites Of The Weltevreden Formation, Barberton Greenstone Belt, South Africa: Implications For The Chemistry And Temperature Of The Archean Mantle, Keena Kareem Jan 2005

Komatiites Of The Weltevreden Formation, Barberton Greenstone Belt, South Africa: Implications For The Chemistry And Temperature Of The Archean Mantle, Keena Kareem

LSU Doctoral Dissertations

The komatiites of the 3.29 Ga Weltevreden Formation, Barberton Greenstone Belt, South Africa represent extremely magnesian lavas derived from the Archean mantle. Three related papers are presented on aspects of the temperature and composition of the Archean mantle, and surface alteration processes. Petrographical and geochemical analyses confirm that olivines from the komatiites retain much of their original igneous character, containing fresh olivines, pyroxenes, and chromites. The olivines from the Weltevreden Formation are extremely magnesian, with Fo contents up to 95.6. Primitive mantle normalized Gd/Yb values near 1, and Al2O3/TiO3 values of 26-33 for these rocks …

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Sulfur And Oxygen Isotope Characterization Of An Eocene Playa Deposit, Northern High Plains, And Rainwater Sulfate, Baton Rouge, Usa, Kathryn Ann Jenkins Jan 2005

Sulfur And Oxygen Isotope Characterization Of An Eocene Playa Deposit, Northern High Plains, And Rainwater Sulfate, Baton Rouge, Usa, Kathryn Ann Jenkins

LSU Master's Theses

This thesis is composed of two independent chapters which are linked through the application of multiple stable isotope measurements of sulfate. Chapter 1 compares two Cenozoic playa deposits in the northern High Plains. Anomalous playa sulfate was discovered at Scotts Bluff which is speculated to have originated via the oxidation of volcanically emitted reduced sulfur gases. A question arises, then, is a volcanic origin of sulfate common for other Cenozoic playa deposits in the region. A complete stable isotope characterization was performed on the gypsum sulfate collected at Wolf Butte (nearby apparent playa setting) to determine if the sulfate has …

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Molluscan Taphonomy As A Proxy For Recognizing Fossil Seagrass Beds, Jill Suzanne Leonard-Pingel Jan 2005

Molluscan Taphonomy As A Proxy For Recognizing Fossil Seagrass Beds, Jill Suzanne Leonard-Pingel

LSU Master's Theses

Seagrass beds, important marine ecosystems both economically and environmentally, have a poor fossil record. As a result, little is known about the geographic distribution of seagrasses over historic and geologic time, or their abundance when unaltered by anthropogenic effects. The purpose of this study is to define a taphonomic signature unique to seagrass beds that can be used as a proxy for identifying the seagrass habitat in the fossil record. In order to develop this proxy, sediment samples from Recent seagrass and non-seagrass environments were collected, and the molluscan bioclasts from these samples were categorically ranked for the following taphonomic …

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Using Ground Penetrating Radar, Light Detection And Ranging, Geodetic Leveling, And Area Hydrogeology To Study The Baton Rouge And Scotlandville Faults, East Baton Rouge Parish, La, Angela Mooi Thomas Jan 2005

Using Ground Penetrating Radar, Light Detection And Ranging, Geodetic Leveling, And Area Hydrogeology To Study The Baton Rouge And Scotlandville Faults, East Baton Rouge Parish, La, Angela Mooi Thomas

LSU Master's Theses

East Baton Rouge Parish, Louisiana, is situated on at least two faults, the Baton Rouge Fault and the Denham Springs-Scotlandville Fault. These faults have surface expressions in the form of escarpments and damage to man-made structures. The purpose of this thesis is to study these faults in the shallow subsurface, in climate and soils found in Louisiana, and to study their ability to block fluid flow and whether groundwater withdrawal influences the amount and rate of subsidence along these faults. Techniques used to gather field data or to research and compile previously acquired data for this thesis includes: Ground Penetrating …

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Morphologic And Stratigraphic Evolution Of The Antarctic Peninsula, Pacific Margin, Jason Henry Holloman Jan 2005

Morphologic And Stratigraphic Evolution Of The Antarctic Peninsula, Pacific Margin, Jason Henry Holloman

LSU Master's Theses

Rebesco et al. (1998) proposed a general depositional model that relates sediment drift evolution on the Antarctic Peninsula Pacific-margin continental rise to glacial processes on the continental shelf. In their model, terrigenous sediment was directly delivered to the rise and contributed to the construction of large sediment drifts when grounded ice extended to the shelf edge. In this scenario, large volumes of fluidized sediment by-passed the margin at the mouth of ice streams (i.e., fast flowing ice), whereas prograding slopes were constructed on those portions of the shelf margin between major ice streams. This model relies heavily on the modern …

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Carbonate Records Of Submarine Hydrocarbon Venting: Northern Gulf Of Mexico, Matthew S. Hackworth Jan 2005

Carbonate Records Of Submarine Hydrocarbon Venting: Northern Gulf Of Mexico, Matthew S. Hackworth

LSU Doctoral Dissertations

Hydrocarbon seep sediments are examined from 3 sites in the Gulf of Mexico (Green Canyon Lease Blocks 232, 185, and 272) to relate the effects of gas hydrates and hydrocarbons on microbial process, pore fluid chemistry, and the processes of authigenic carbonate formation. Hydrocarbon-fueled microbial reactions result in pore fluids with lowered SO42- (all consumed by –10 cm) and enrichments in H2S, alkalinity, and DIC (up to 20 mmol, 30 meq/L, and 18 mmol/L, respectively) which promote carbonate formation. Pore fluid d13CDIC (PDB) is influenced by thermogenic hydrocarbons and crude oil in GC …

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The Stable Isotope Stratigraphy And Paleosols Of North America's Most Southern Exposure Of Late Paleocene/Early Eocene Fossiliferous Continental Deposits: Documenting The Initial Eocene Thermal Maximum In Big Bend National Park, Texas, Paul David White Jan 2005

The Stable Isotope Stratigraphy And Paleosols Of North America's Most Southern Exposure Of Late Paleocene/Early Eocene Fossiliferous Continental Deposits: Documenting The Initial Eocene Thermal Maximum In Big Bend National Park, Texas, Paul David White

LSU Doctoral Dissertations

A chemostratigraphic section across the Paleocene/Eocene boundary, using the stable isotopes of carbon and oxygen, has been developed for North America's most southern exposure of early Paleogene continental deposits in which the boundary is constrained by fossil mammals. A negative carbon excursion has been identified within C24r. The range in d13C values is from -8.1 to -13.2‰. Until the development of the chemostratigraphic section it was uncertain if the earliest Eocene was recorded in Big Bend. An early Wasatchian (Wa1) fossil site occurs stratigraphically higher than the carbon excursion and has yielded the stratigraphically lowest Hyracotherium in the …

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Magnetic Susceptibility For The Paleocene-Eocene Boundary: Correlation Among Three Egyptian Sections, Kelli Willson Jan 2004

Magnetic Susceptibility For The Paleocene-Eocene Boundary: Correlation Among Three Egyptian Sections, Kelli Willson

Honors Capstones

No abstract provided.

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Enhanced Flushing With Cyclodextrin For The Remediation Of Creosote Contaminated Soil, Monalisa Dutta Jan 2004

Enhanced Flushing With Cyclodextrin For The Remediation Of Creosote Contaminated Soil, Monalisa Dutta

LSU Master's Theses

Past practices of applying creosote and coal tar preservatives to wood, such as unlined pits and trenches, have resulted in contamination of the surface and ground water at thousand of sites. The low aqueous solubility, volatility and bioavailability of many these constituents limit their degradation by natural attenuation and standard remediation techniques such as ground water flushing, soil vapor extraction, and bioremediation. While research has shown that cyclodextrin solutions have the ability to enhance the solubility of some of the components of creosote, additional work is needed to evaluate its potential as a remedial agent for these sites. Equilibrium batch …

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Post Monitoring Of A Cyclodextrin Remediated Chlorinated Solvent Contaminated Aquifer, Rebecca Mary Hinrichs Jan 2004

Post Monitoring Of A Cyclodextrin Remediated Chlorinated Solvent Contaminated Aquifer, Rebecca Mary Hinrichs

LSU Master's Theses

Hydroxypropyl-β-cyclodextrin (HPβCD) has been tested successfully in the laboratory and in the field for enhanced flushing of low-polarity contaminants from aquifers. The cyclodextrin molecule forms a toroidal structure, which has a hydrophobic cavity. Within this cavity, organic compounds of appropriate shape and size can form inclusion complexes, which is the basis for the use of cyclodextrin in groundwater remediation. The hydrophilic exterior of the molecule makes cyclodextrin highly water-soluble. The solubility of cyclodextrins can be further enhanced by adding functional groups, such as hydroxypropyl groups, to the cyclodextrin core. The aqueous solubility of HPβCD exceeds 950 g/L. These high solubilities …

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Seismic Stratigraphic Investigation Of The Ukpokiti Field Channel Complex, Oml 108, Offshore Nigeria, Northwestern Niger Delta, Toby Latwan Stewart Jan 2004

Seismic Stratigraphic Investigation Of The Ukpokiti Field Channel Complex, Oml 108, Offshore Nigeria, Northwestern Niger Delta, Toby Latwan Stewart

LSU Master's Theses

Detailed seismic stratigraphic analyses and mapping show that a well defined Ukpokiti Field Channel complex (late Miocene) found on the up-thrown side of a major back-to-back fault system in the West Niger delta inner-continental shelf probably formed during a single eustatic fall. The channel (>500 msec, 10 km wide) shows several tributaries entering the trunk axis from what was probably a surface of subaerial exposure. Slumping is prominent on the north flank of the trunk channel. No channel unconformity is evident in the down-thrown block. This investigation seeks to resolve the lack of down-dip correlative seismic expression across the …

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Nature And Dynamics Of Late Miocene/Early Pliocene Ice-Sheet Grounding Events On The Pacific Margin Of The Antarctic Pennisula Outer Continental Shelf, David C. Egan Jan 2004

Nature And Dynamics Of Late Miocene/Early Pliocene Ice-Sheet Grounding Events On The Pacific Margin Of The Antarctic Pennisula Outer Continental Shelf, David C. Egan

LSU Master's Theses

Package-3 unconformities identified by Bart and Anderson (1995) were mapped to evaluate their glacial unconformity interpretation using a regional grid of single channel seismic data from the Antarctic Peninsula outer continental shelf. Detailed correlations show many crosscutting relationships within Package 3 such that the unconformities and units they bound are not regionally continuous across the margin. Comparison of Package-3 unconformities with the modern bathymetry reveals that cross-shelf trough and bank morphology is absent, which indicates that ice streams probably did not exist on the shelf during Package-3 time. On the continental shelf, only the middle part of Package 3 is …

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Migmatization Of Archean Aluminous Metasediments From The Eastern Beartooth Mountains, Montana, U.S.A., Andrew T. Maas Jan 2004

Migmatization Of Archean Aluminous Metasediments From The Eastern Beartooth Mountains, Montana, U.S.A., Andrew T. Maas

LSU Master's Theses

Geothermobarometry, mineral compositions and textures, and thermodynamic models suggest biotite dehydration melting occurred in the peraluminous rocks of the eastern Beartooth Mountains. These Archean metapelitic migmatites are metatexites and diatexites, and have typical metamorphic assemblages of Qtz + Pl + Kfs + Bt + Sil +/- Grt +/- Crd. The subsequent in situ crystallization of the magma derived from the biotite dehydration created migmatitic leucosomes in the rocks. These leucosomes are primarily composed of quartz, plagioclase and potassium feldspar. Water derived from the dehydration of biotite was dissolved in the melted phase. Crystallization of the magma reintroduced this water to …

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Overlap Zones, Growth Faults, And Sedimentation: Using High Resolution Gravity Data, Livingston Parish, La, Carrie Alison Cazes Jan 2004

Overlap Zones, Growth Faults, And Sedimentation: Using High Resolution Gravity Data, Livingston Parish, La, Carrie Alison Cazes

LSU Master's Theses

In south Louisiana, parallel to the coast of the Gulf of Mexico, are belts of east-to-west trending, listric-normal faults with associated contemporaneous sedimentation and fault movement. The Tepetate-Baton Rouge Fault system in south-central Louisiana contains individual fault segments which are arcuate and overlap each other in map view, as seen on LiDAR data. Gravity survey data, with a sample spacing of 20 to 50 m, was collected across normal fault scarps. Structural ramps may form in the area between overlapping normal fault segments creating an east-to-west gradient. This gradient change may divert streams and provide areas for coarse-grained sediments to …

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A Comparison Of A High-Resolution Survey And A Three-Dimensional Seismic Survey In A Feature-Rich Region Of The Green Canyon Area, Gulf Of Mexico, Bruce Miles Samuel Jan 2004

A Comparison Of A High-Resolution Survey And A Three-Dimensional Seismic Survey In A Feature-Rich Region Of The Green Canyon Area, Gulf Of Mexico, Bruce Miles Samuel

LSU Master's Theses

Recent advances in Autonomous Underwater Vehicle (AUV) technology have revolutionized the positioning and accuracy of high-resolution deep sea mapping tools. Geologic hazard and engineering surveys by AUV’s are producing high-resolution data sets of a quality that has never before been seen. Three-dimensional (3D) seismic data, though traditionally used for only deep subsurface mapping of large areas, is now being reprocessed at a higher resolution and utilized in well site investigations and geologic hazard assessments. This study makes a comparison between a 3D seismic survey and an AUV high-resolution survey in order to determine the strengths and weaknesses of both of …

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Foreland Basins: Lithospheric Flexure, Plate Strength And Regional Stratigraphy, John Londono Jan 2004

Foreland Basins: Lithospheric Flexure, Plate Strength And Regional Stratigraphy, John Londono

LSU Doctoral Dissertations

Foreland basin subsidence through time is reproduced in this study, as the flexure of an elastic beam in an inviscid fluid under the vertical stress, caused by discrete-distributed loads. Thus, seismostratigraphic data from the Timor Sea peripheral foreland basin, in northwestern Australia, and the Putumayo retroarc foreland basin in the Colombian Andes, are forward modeled, at chronostratigraphic intervals, to assess the evolving geodynamic conditions of the basins. Results show that the accommodation in foreland basins varies as the depositional basement is vertically adjusted according to the regionally isostatic compensation of the lithosphere. Distributed tectonic (thrust belts) and sedimentary loads that …

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Compositional Systematics Of Deep, Low Salinity Formation Waters In The Upper Wilcox Of Southeastern Texas, Kathleen (Kt) Moran Jan 2003

Compositional Systematics Of Deep, Low Salinity Formation Waters In The Upper Wilcox Of Southeastern Texas, Kathleen (Kt) Moran

LSU Master's Theses

Overpressured Eocene Wilcox sandstones in the Newton County, Texas Sabine Tram field contain water with salinities ranging from 14 to 28 g/L. The solutes appear to fall loosely into three groups. Na, Ca, and Mg follow systematics previously known globally for saline formation waters whereby their concentrations are controlled by fluid-mineral equilibrium. Cl, Br, I, and B are conservatively diluted constituents of some saline endmember that is not solely connate marine. Potassium does not follow any known basinal systematic, and the formation water is supersaturated with respect to SiO2 by an order of magnitude. Meteoric water is not a probable …

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Detrital Tourmaline As An Indicator Of Provenance: A Chemical And Sedimentological Study Of Modern Sands From The Black Hills, South Dakota, David Brent Viator Jan 2003

Detrital Tourmaline As An Indicator Of Provenance: A Chemical And Sedimentological Study Of Modern Sands From The Black Hills, South Dakota, David Brent Viator

LSU Master's Theses

Detrital tourmaline has proven useful as a provenance indicator mineral of ancient sedimentary/metasedimentary units due to its presence in many rock types, chemical responsiveness to environments of formation, complex and variable chemical compositions, high resistance to chemical and mechanical weathering, and stability through diagenesis and metamorphism. This study further establishes detrital tourmaline as a provenance indicator mineral by examining the chemical and sedimentological relationships between modern detrital tourmalines in the sediments of the Black Hills, South Dakota, USA, and in situ tourmalines from southern Black Hills’ tourmaline-bearing metasedimentary rocks, granites, and rare-element enriched pegmatites. Results show that detrital tourmaline is …

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An Investigation Of A Salt-Dome Environment At South Timbalier 54, Gulf Of Mexico, Robert E. Little, Jr Jan 2003

An Investigation Of A Salt-Dome Environment At South Timbalier 54, Gulf Of Mexico, Robert E. Little, Jr

LSU Master's Theses

Salt domes have been studied in the Gulf Coast region to look at how, why, and where saline waters are located within these field areas. Fluid flow model and pathway studies can be helpful to the research of saline water migration because it can be correlated to hydrocarbon migration in petroleum exploration. The South Timbalier 54 field occurs over a salt dome that sits at approximately 3,048 meters beneath the seafloor. Two major faults were found originating from the salt dome up into the shallow section of the field. The sands were deposited in fluvial, deltaic, or marine environments. The …

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Correlation Of Core Characteristics To Outcrop Upper Jackfork Group Turbidites, Degray Lake, Arkansas, Daniel James Golob Jan 2003

Correlation Of Core Characteristics To Outcrop Upper Jackfork Group Turbidites, Degray Lake, Arkansas, Daniel James Golob

LSU Master's Theses

Pennsylvanian age Jackfork Group cores from the DeGray Lake Dam and outcrop from the east wall of the DeGray Lake Spillway, Arkansas, provide an opportunity for a detailed study on the transport and depositional characteristics of a fine-grained, deep-water depositional system. Two phases of resedimentation processes are responsible for deposition of the sediments in the cores and the outcrop. Primary resedimentation processes transport terrigenous sediments from the shelf or basin edge into the middle fan environment, while secondary resedimentation alter the sediments after they are initially deposited in the environment. Debris flows, slurry flows, and high and low density turbidity …

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Middle Miocene Grounding Events On The Ross Sea Outer Continental Shelf, Antarctica, Juan Manuel Chow Jan 2003

Middle Miocene Grounding Events On The Ross Sea Outer Continental Shelf, Antarctica, Juan Manuel Chow

LSU Master's Theses

The middle Miocene δ18O enrichments from deep-sea data and eustatic sea level falls are traditionally attributed to expansion of the East Antarctic Ice Sheet. Interpretations of such data have led many to conclude that the West Antarctic Ice Sheet (WAIS) was not well-developed until the late Miocene. In such a scenario, middle Miocene glaciation on the Ross Sea shelf would have had to be minimal, perhaps in the form of ice caps, to be consistent with proxy data. New seismic-stratigraphic analysis of the Ross Sea outer continental shelf suggests that at least five grounding events (ice sheet advances …

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Low Salinity Waters In Deep Sedimentary Basins, David Scott Szalkowski Jan 2003

Low Salinity Waters In Deep Sedimentary Basins, David Scott Szalkowski

LSU Master's Theses

While the composition and origin of brines in deep sedimentary basins has been extensively discussed, the composition and origin of low salinity waters is not as well documented. Since the 1960s, the presence of deep, low-salinity waters has been observed in some sedimentary basins and is commonly present in overpressured sections. The episodic release of low salinity, overpressured fluids upward into sediments containing high salinity formation waters likely occurs at <100-year intervals. Because there is a growing body of evidence that suggests mixing formation waters of varying salinity could induce the dissolution and precipitation of minerals, it is important to have detailed information about chemical compositions of both end-member fluids to adequately predict such mixing results. This study concludes that low salinity waters (<35 g/l) are generally not unique in major solute composition when compared to high salinity waters (>35 g/l). On log-log plots, monovalent cations plot along 1:1 slopes with respect to salinity and total anionic charge, while divalent cations plot along 2:1 slopes. However, this study concludes …

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Biomechanical Reconstruction Of The Appendicular Skeleton In Three North American Jurassic Sauropods, Ray Wilhite Jan 2003

Biomechanical Reconstruction Of The Appendicular Skeleton In Three North American Jurassic Sauropods, Ray Wilhite

LSU Doctoral Dissertations

Forelimb and hindlimb articulation, reconstructed musculature, and function were examined in Apatosaurus, Diplodocus, and Camarasaurus. A technique was developed using a Microscribe three-dimensional digitizer to capture external morphological data for skeletal reconstruction and determination of taxonomically useful features. The appendicular musculature of Alligator mississippiensis was dissected to determine form, function, origin, and insertion of muscles to aid in reconstruction of sauropod musculature. Contrary to the literature, M. caudofemoralis longus was found to originate primarily from the lateral surfaces of the proximal chevrons instead of the bodies and transverse processes of the caudals, demonstrating that chevron morphology is indicative of the …

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Characterization Of The Lower Atoka Formation, Arkoma Basin, Central Arkansas, Kelly R. Lagrange Jan 2002

Characterization Of The Lower Atoka Formation, Arkoma Basin, Central Arkansas, Kelly R. Lagrange

LSU Master's Theses

The Carboniferous Lower Atoka outcrops in the Arkoma Basin of Central Arkansas contain turbidite deposits in a channelized and unchannelized submarine fan setting. The objectives of the study were to determine depositional characteristics and reservoir performance of these fine-grained submarine fan deposits. Four outcrops (Highway 5, Perryville, Chula, and Danville) were studied and described in detail emphasizing sedimentary facies, vertical succession of beds, sedimentary structures, and other small-scaled features that cannot be resolved in subsurface deposits. Five distinct sedimentary facies were recognized: Facies A - massive sandstones, Facies B - thin-bedded sandstones with a mudstone drape, Facies C - interbedded …

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Sedimentology And Stratigraphy Of The Upper Cretaceous-Paleocene El Molino Formation, Eastern Cordillera And Altiplano, Central Andes, Bolivia: Implications For The Tectonic Development Of The Central Andes, Richard John Fink Jan 2002

Sedimentology And Stratigraphy Of The Upper Cretaceous-Paleocene El Molino Formation, Eastern Cordillera And Altiplano, Central Andes, Bolivia: Implications For The Tectonic Development Of The Central Andes, Richard John Fink

LSU Master's Theses

The Upper Cretaceous-Paleocene El Molino Formation of the Bolivian Central Andes consists of mixed siliciclastic and carbonate strata alternately interpreted as syn-rift, post-rift thermal sag and foreland basin deposits. These deposits can be divided into two lithostratigraphic sequences. The first sequence consists of a carbonate, carbonate sand and mudrock lower member, a middle member consisting entirely of mudrock and an upper member containing carbonates and mudrocks. The second lithostratigraphic sequence contains a lower member composed of carbonate sands, carbonates and mudrocks, and an upper member consisting of a coarsening upwards sequence of sandstones and mudrocks. Within these lithostratigraphic sequences, five …

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Overpressuring, Diagenesis, And Fluid Flow At The Matagorda Island 519 Field, Offshore Texas, Gulf Of Mexico, Kera Gautreau Spears Jan 2002

Overpressuring, Diagenesis, And Fluid Flow At The Matagorda Island 519 Field, Offshore Texas, Gulf Of Mexico, Kera Gautreau Spears

LSU Master's Theses

The relations between overpressuring, diagenesis, and fluid flow in sedimentary basins are complex and multifaceted. The Matagorda Island 519 field (MI 519), offshore Texas, provides an excellent area for investigating some of these relations. The top of overpressure at MI 519 occurs at a depth of 3.5 to 3.8 km in a Lower Miocene deltaic sequence. On the basis of log-derived lithostratigraphy, the pressure seal does not appear to be lithologic in origin. Geochemical, mineralogical, and cuttings information indicate instead that the precipitation of diagenetic calcite and possibly quartz cements has been the major factor in seal development. Stratigraphic variation …

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Early-Middle Tertiary Deposition In The Corque Syncline, Altiplano Plateau, Bolivia, Brian A. Hampton Jan 2002

Early-Middle Tertiary Deposition In The Corque Syncline, Altiplano Plateau, Bolivia, Brian A. Hampton

LSU Master's Theses

Tertiary age rocks are exposed along north-south trending structures throughout the hinterland Altiplano plateau, central Andes. The east limb of the Corque syncline (SW Bolivia) contains the thickest and most continuous successions of late Eocene–Oligocene age non-marine strata (Potoco Formation) on the Altiplano. The Potoco is up to ~6500 m thick and has continuous exposure >103 km2 making it the thickest and most extensive remnant of the mid-Tertiary Altiplano basin. Basin fill during late Eocene–Oligocene time remains the most rapid and sustained period of deposition since Andean orogenesis, recording a long-term sediment accumulation rate of ~0.5 mm/my. The …

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Significance Of Variations Among Ancient Deltaic Deposits In The Arkoma Basin, North-Central Arkansas, Christine Michelle Wright Jan 2002

Significance Of Variations Among Ancient Deltaic Deposits In The Arkoma Basin, North-Central Arkansas, Christine Michelle Wright

LSU Master's Theses

The Arkoma Basin is one of several foreland basins formed in association with the Ouachita orogeny. The Arkoma Basin has been studied in depth with regard to stratigraphy, depositional environments, structure and its relationship to the Appalachian-Ouachita orogenic event. This study focuses on the variability of the deltaic deposits within the Arkoma Basin and the significance of the variables to both the delta complex and the overall tectonic setting. The specific characteristics to be investigated include variations in paleocurrent directions, bed thicknesses, bed geometries, organic contents, sand/shale ratios, mineral assemblages and fossil assemblages. In the case of the Arkoma deltaic …

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Distributary Mouth Bar Formation And Channel Bifurcation In The Wax Lake Delta, Atchafalaya Bay, Louisiana, Anton J. Dumars Jan 2002

Distributary Mouth Bar Formation And Channel Bifurcation In The Wax Lake Delta, Atchafalaya Bay, Louisiana, Anton J. Dumars

LSU Master's Theses

The Mississippi River has undergone at least seven cyclic avulsions during the Holocene epoch. The latest avulsion, down the Atchafalaya River into the Gulf of Mexico, has produced two bayhead deltas prograding into Atchafalaya Bay. The Wax Lake Delta, typical of other Mississippi sub-deltas, has a natural anastomosing channel pattern. In contrast, the Atchafalaya Delta, situated in the eastern side of the Bay, has experienced sporadic and limited growth due to the dredging of a navigation channel below natural depth. Channel bifurcation, and sediment transport processes and responses, were investigated in the Wax Lake Delta, using channel flow velocities, suspended …

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