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2006

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Articles 31 - 60 of 172

Full-Text Articles in Geology

Seaside, Oregon, Tsunami Pilot Study : Modernization Of Fema Flood Hazard Maps, Frank I. González, Eric L. Geist, Costas Synolakis, Diego Rodriguez Arcas, Douglas Bellomo, David Carlton, Thomas Horning, Bruce Jaffe, Jeff Johnson, Utku Kânoğlu, Harold O. Mofjeld, Jean Newman, Thomas Parsons, Robert Peters, Curt D. Peterson, George Priest, Vasily V. Titov, Angie J. Venturato, Joseph Weber, Florence L. Wong, Ahmet Yalçıner Aug 2006

Seaside, Oregon, Tsunami Pilot Study : Modernization Of Fema Flood Hazard Maps, Frank I. González, Eric L. Geist, Costas Synolakis, Diego Rodriguez Arcas, Douglas Bellomo, David Carlton, Thomas Horning, Bruce Jaffe, Jeff Johnson, Utku Kânoğlu, Harold O. Mofjeld, Jean Newman, Thomas Parsons, Robert Peters, Curt D. Peterson, George Priest, Vasily V. Titov, Angie J. Venturato, Joseph Weber, Florence L. Wong, Ahmet Yalçıner

Geology Faculty Publications and Presentations

FEMA Flood Insurance Rate Map (FIRM) guidelines do not currently exist for conducting and incorporating tsunami hazard assessments that reflect the substantial advances in tsunami research achieved in the last two decades; this conclusion is the result of two FEMA-sponsored workshops and the associated Tsunami Focused Study (Chowdhury et al., 2005). Therefore, as part of FEMA's Map Modernization Program, a Tsunami Pilot Study was carried out in the Seaside/Gearhart, Oregon, area to develop an improved Probabilistic Tsunami Hazard Assessment (PTHA) methodology and to provide recommendations for improved tsunami hazard assessment guidelines. The Seaside area was chosen because it is typical …


Evidence Of An Active Enso And Pdq During The Mid-Holocene From A Costa Rican Speleothem, April D. Azouz Aug 2006

Evidence Of An Active Enso And Pdq During The Mid-Holocene From A Costa Rican Speleothem, April D. Azouz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Although the El Nino/Southern Oscillation (ENSO) is the most important source of inter-annual climate variability in the tropics, its Holocene history is poorly understood, particularly in Central America. A high resolution (-3.8 years/sample) paleoclimate record of Central American rainfall variability has been reconstructed from a U /Th-dated stalagmite (7890 to 6490 yrs B.P.) from Costa Rica to constrain the onset and variability of ENSO throughout the Holocene, and to determine its role in generating regional climate anomalies. I suggest drier conditions, forced by El Nino, are represented by higher 5180 values, and are correlative with higher 513C values, indicating that …


Sediment Characteristics And Hydrodynamic Setting Of Reef Platform Sediments Of Kunduchi, North Of Dar Es Salaam Harbour, Y. W. Shaghude, N. Nyandwi, A. N. N. Muzuka, A. M. A. M. Dubi, O. U. Mwaipopo Jul 2006

Sediment Characteristics And Hydrodynamic Setting Of Reef Platform Sediments Of Kunduchi, North Of Dar Es Salaam Harbour, Y. W. Shaghude, N. Nyandwi, A. N. N. Muzuka, A. M. A. M. Dubi, O. U. Mwaipopo

Tanzania Journal of Science

Sediment grain size distribution, carbonate content and current velocities for the Kunduchi area are used to determine its hydrodynamic setting and sediment characteristics. The sediment mean grain size generally decreases northward. The sediments consist of medium to coarse sand south of the Tegeta River and fine sand further north. The sediment sorting values, which lack a north-south trend, vary from moderately well sorted to poorly sorted. The skewness of the sediment vary from near-symmetrical to very negatively skewed while the peakedness (kurtosis) varies from platykurtic to leptokurtic. The carbonate content increases with distance offshore, whereas the siliciclastic component decreases with …


Stable Isotope Compositions Of Organic Carbon And Contents Of Organic Carbon And Nitrogen Of Lacustrine Sediments From Sub-Arid Northern Tanzania, Ann Muzuka Jul 2006

Stable Isotope Compositions Of Organic Carbon And Contents Of Organic Carbon And Nitrogen Of Lacustrine Sediments From Sub-Arid Northern Tanzania, Ann Muzuka

Tanzania Journal of Science

The stable isotope compositions of organic carbon (OC), and contents of OC and nitrogen for four sediment cores recovered from lakes Makat (located in the Ngorongoro Crater), Ndutu and Masek (located in the Serengeti Plains) are used to document sources of organic matter (OM) and climatic changes in sub-arid northern Tanzania during the late Pleistocene-Holocene period. Accelerate mass spectrometer (AMS) 14C ages on total OM for sediments collected from the Ngorongoro Crater Lake indicate that the sedimentation rate is approximately 17 cm/ka. The δC values from the 20 cm long core (short core) show a downcore increase, whereas that of …


The Provenance Of Eocene Tuff Beds In The Fossil Butte Member Of The Green River Formation Of Wyoming: Relation To The Absaroka And Challis Volcanic Fields, Matthew R. Chandler Jul 2006

The Provenance Of Eocene Tuff Beds In The Fossil Butte Member Of The Green River Formation Of Wyoming: Relation To The Absaroka And Challis Volcanic Fields, Matthew R. Chandler

Theses and Dissertations

The Green River Formation was deposited between 53.5 and 48.5 Ma. The Angelo, Fossil Butte, and Lower members of the Green River Formation at Fossil Basin, preserve ash fall tuffs deposited in ancient Fossil Lake. 40Ar/39Ar dating of sanidine yielded eruptive ages of 51.29 ± 1.29 Ma and 52.20 ± 3.08 Ma for two of the tuff beds within Fossil Basin. Immobile element and mineral compositions of Fossil Basin tuffs indicate that most tuffs erupted from a subduction zone originally as rhyolites and dacites. X-ray diffraction analyses reveal that the tuffs' glassy matrices have been altered to illite, calcite, clinoptilolite, …


Geophysical Investigations And Groundwater Modeling Of The Hydrologic Conditions At Masaya Caldera, Nicaragua, Richard Eric Macneil Jul 2006

Geophysical Investigations And Groundwater Modeling Of The Hydrologic Conditions At Masaya Caldera, Nicaragua, Richard Eric Macneil

USF Tampa Graduate Theses and Dissertations

Masaya volcano, Nicaragua, has been the site of tremendous Plinian basaltic eruptions. Two eruptions ~6,500 and 2,250 BP formed the 6 kilometer (km) x 11 km, northwest trending Masaya caldera. The present day active Santiago Crater within the caldera is the site of persistent volcano degassing and occasional phreatic explosions. While the mechanism responsible for these phreatic explosions is unclear, one possible explanation is the interaction of groundwater with the shallow magma chamber beneath Masaya. This interaction with meteoric water is supported by the substantial steam discharge from the vent, which is significantly larger than other similar volcanoes in the …


Anguilliform Larvae Collected Off North Carolina, Steve W. Ross, Tara L. Casazza, Andrea M. Quattrini, Kenneth J. Sulak Jul 2006

Anguilliform Larvae Collected Off North Carolina, Steve W. Ross, Tara L. Casazza, Andrea M. Quattrini, Kenneth J. Sulak

United States Geological Survey: Staff Publications

The distinctive larval stage of eels (leptocephalus) facilitates dispersal through prolonged life in the open ocean. Leptocephali are abundant and diverse off North Carolina, yet data on distributions and biology are lacking. The water column (from surface to 1,293 m) was sampled in or near the Gulf Stream off Cape Hatteras, Cape Lookout, and Cape Fear, North Carolina during summer through fall of 1999–2005, and leptocephali were collected by neuston net, plankton net, Tucker trawl, and dip net. Additional samples were collected nearly monthly from a transect across southern Onslow Bay, North Carolina (from surface to 91 m) from April …


A Stratigraphic And Geochronologic Analysis Of The Morrison Formation/Cedar Mountain Formation Boundary, Utah, Brent W. Greenhalgh Jul 2006

A Stratigraphic And Geochronologic Analysis Of The Morrison Formation/Cedar Mountain Formation Boundary, Utah, Brent W. Greenhalgh

Theses and Dissertations

The Lower Cretaceous Cedar Mountain Formation preserves several vertebrate faunas and has the potential of providing critical timing information pertaining to Early Cretaceous dinosaurs and the Sierran magmatic arc. Historically, the Morrison/Cedar Mountain contact and the duration of the unconformity between them have been difficult or impossible to determine because 1) the formations were deposited in similar environments, 2) the basal Cedar Mountain Formation is composed of reworked Morrison Formation, and 3) there are no radiometric ages for the lower Cedar Mountain Formation. A stratigraphic study through central Utah reveals a diagnostic suite of pedogenic and sedimentologic characters across the …


Characterization Of Fracture Systems In Sublette County, Wyoming Using P-Wave And C-Wave 3d Seismic, Keith R. Johnson Jul 2006

Characterization Of Fracture Systems In Sublette County, Wyoming Using P-Wave And C-Wave 3d Seismic, Keith R. Johnson

Masters Theses

Birefringence of seismic shear waves has proven to be a useful tool for identifying fracture intensity and orientation in the subsurface. Naturally occurring fractures have been shown to contribute to the deliverability of natural gas production in some reservoir formations in Rocky Mountain sedimentary basins. A multicomponent 3D 3C seismic survey acquired on the southeastern end of Pinedale Anticline in Sublette County, Wyoming was mapped to characterize fault systems within the sedimentary section. The tectonic and depositional history in the study area was determined by literature search and by one-dimensional backstripping. Compressional and wrench fault systems were observed and mapped. …


Field Studies Of Hydrophobic Filter Pack Performance In Free Product Monitoring And Recovery, Nathan J. Brandner Jul 2006

Field Studies Of Hydrophobic Filter Pack Performance In Free Product Monitoring And Recovery, Nathan J. Brandner

Masters Theses

Multiple field experiments were conducted to determine the performance of hydrophobic filter packs, compared to the hydrophilic industry standard filter pack in free product hydrocarbon recovery. Laboratory and field studies have been previously performed in support of enhancing free product hydrocarbon recovery with the use of hydrophobic filter pack designs. This study was an attempt to test the efficacy of using hydrophobic filter pack materials to enhance free product recovery.

Six recovery wells were installed at three field sites, each site utilizing a pair of recovery wells, one hydrophobic and one hydrophilic, to compare their performances. Fine-grained hydrophobic filter pack …


Sedimentology And Stratigraphy Of The Pennsylvanian Saginaw Aquifer, Central Lower Michigan, U.S.A., Niah B. H. Venable Jul 2006

Sedimentology And Stratigraphy Of The Pennsylvanian Saginaw Aquifer, Central Lower Michigan, U.S.A., Niah B. H. Venable

Masters Theses

The Saginaw Aquifer is an important bedrock aquifer serving the needs of over 400,000 people in the Tri-County area of the Central Lower Peninsula of Michigan. The aquifer is comprised of the Pennsylvanian Grand River and Saginaw Formations. This study focuses on expanding existing knowledge of the general sedimentologic and stratigraphic characteristics of these units using conventional geological methods including core analysis, local log to core correlation, local and regional log to log correlation, and biostratigraphy. Analysis of new core from the study area examines facies and depositional environments given cursory coverage in outcrop studies by past researchers.

Incised valley …


Geologic Map And Structural Analysis Of The Twin Rocks 7.5 Minute Quadrangle, Wayne County, Utah, Samuel C. Sorber Jun 2006

Geologic Map And Structural Analysis Of The Twin Rocks 7.5 Minute Quadrangle, Wayne County, Utah, Samuel C. Sorber

Theses and Dissertations

A new geologic map of the Twin Rocks 7.5 minute quadrangle primarily located within Capitol Reef National Park, south-central Utah, provides stratigraphic and structural detail not previously available. This map has also been instrumental in understanding the evolution and development of fluvial terraces associated with Sulfur Creek and the structural geology of the backlimb of the Miners Mountain uplift. Nine bedrock stratigraphic formations and eight types of Quaternary deposits were mapped throughout the quadrangle. Bedrock stratigraphy ranges in age from Permian to Jurassic. New details absent on previous geologic maps include members of the Chinle and Moenkopi Formations and the …


Dendrochronological Analysis Of Smithville Community Historical Society Cabin And House, Smithville, Ohio Jun 2006

Dendrochronological Analysis Of Smithville Community Historical Society Cabin And House, Smithville, Ohio

Historic Structures

Dating historical structures in Wayne County, Ohio using dendrochronology. The Historical Structures collection consists of reports that are the result of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Lehmann, Sophie; Wiles, Greg


Kinematics Of Orocline Tightening In The Core Of An Arc: Paleomagnetic Analysis Of The Ponga Unit, Cantabrian Arc, Northern Spain, Arlo Brandon Weil Jun 2006

Kinematics Of Orocline Tightening In The Core Of An Arc: Paleomagnetic Analysis Of The Ponga Unit, Cantabrian Arc, Northern Spain, Arlo Brandon Weil

Geology Faculty Research and Scholarship

Paleomagnetic and structural analyses of the Western European Variscan Belt (WEVB) suggest that the most viable kinematic model for Variscan deformation in northern Iberia is oroclinal bending of an originally linear belt in a two-stage tectonic history. This history represents two regional compression phases (E-W in the Late Carboniferous and N-S in the Permian, both in present-day coordinates), which resulted in the refolding (about steeply plunging axes) of initially north-south trending thrusts and folds in the hinge zone, and oroclinal tightening due to vertical axis rotation of the belt's limbs. However, the orocline model has yet to be critically tested …


Morphologic Features Of Conduits And Aquifer Response In The Unconfined Floridan Aquifer System, West Central Florida, Lee J. Florea, H L. Vacher Jun 2006

Morphologic Features Of Conduits And Aquifer Response In The Unconfined Floridan Aquifer System, West Central Florida, Lee J. Florea, H L. Vacher

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Conduits within the unconfined Floridan Aquifer of west-central Florida include both horizontal and vertical components. In this paper, we investigate each and propose theories based upon cave survey data and a collection of over 300 Florida cave maps. First, we find that vertical portions of conduits visually correlate to fractures, and these fractures tend to be the dominant control of conduit directionality. Length-weighted rose diagrams of passage directions reveal a NW-SE and NE-SW pattern of conduit directions statistically similar to results found in remote sensing studies of photolinears. Secondly we note that horizontal elements of conduits occur at consistent horizons …


Seasonal Sediment Transport And Unusually Large Spit Development At Sandy Point, San Salvador, Bahamas, Vincent J. Voegeli, Alicia L. Simonti, H. Allen Curran Jun 2006

Seasonal Sediment Transport And Unusually Large Spit Development At Sandy Point, San Salvador, Bahamas, Vincent J. Voegeli, Alicia L. Simonti, H. Allen Curran

Geosciences: Faculty Publications

Reprinted from: R.L. Davis & D. Gamble, eds., Proceedings of the 12th Symposium on the Geology of the Bahamas and Other Carbonate Regions, San Salvador, Gerace Research Center


Petrogenesis Of Pleistocene Basalts In The Norris-Mammoth Corridor, Yellowstone National Park, Kristeen Marie Bennett Jun 2006

Petrogenesis Of Pleistocene Basalts In The Norris-Mammoth Corridor, Yellowstone National Park, Kristeen Marie Bennett

UNLV Theses, Dissertations, Professional Papers, and Capstones

The basalts of the Norris-Mammoth corridor within the Yellowstone Plateau volcanic field have an outcrop erupted volume of ~94 km3. Basalt in the Yellowstone Plateau volcanic field is minor in volume compared to 3,700 km3 of felsic lavas, domes, and pyroclastic rocks. The tholeiitic eruptive products formed small Hawaiian-style shield volcanoes. A newly identified volcanic vent, called the Panther Creek vent, within the Swan Lake Flat basalt stratigraphic unit, was primarily Strombolian in its eruption style. This vent is the first recognized cinder cone in Yellowstone National Park.

All basaltic units within the Norris-Mammoth corridor, and the …


Dendrochronological Analysis Of The Morgan House, Wayne County, Wooster, Ohio May 2006

Dendrochronological Analysis Of The Morgan House, Wayne County, Wooster, Ohio

Historic Structures

Dating historical structures in Wayne County, Ohio using dendrochronology. The Historical Structures collection consists of reports that are the result of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Lehmann, Sophie; Wiles, Greg


Geostatistical And Stochastic Study Of Radio Nuclide Transport In The Unsaturated Zone At Yucca Mountain, Ming Ye, Amy J. Smiecinski, Raymond E. Keeler May 2006

Geostatistical And Stochastic Study Of Radio Nuclide Transport In The Unsaturated Zone At Yucca Mountain, Ming Ye, Amy J. Smiecinski, Raymond E. Keeler

Publications (YM)

The U.S. Nuclear Waste Technical Review Board [Cohon et al. 1998] evaluated the technical and scientific validity of activities undertaken by the Secretary of Energy to characterize Yucca Mountain, Nevada, for its suitability as an underground repository in which to store high-level radioactive waste and spent nuclear fuel. In the report, the Board pinpointed that the study on groundwater flow and radionuclide transport in the saturated and unsaturated zones below Yucca Mountain should, over the next several years, focus on reducing prediction uncertainty. In its 2002, the Board repeated this concern by stating, “… hydrogeologic processes that affect radionuclide transport …


Hydrolgeologic Groundwater Sensitivity And Vulnerability Mapping In South Central Kentucky, Andrea Croskrey May 2006

Hydrolgeologic Groundwater Sensitivity And Vulnerability Mapping In South Central Kentucky, Andrea Croskrey

Masters Theses & Specialist Projects

Groundwater sensitivity (Ray and O'dell 1993 a) refers to the inherent ease with which groundwater can be contaminated based on hydrogeologic characteristics. We have developed digital methods for identifying areas of varying groundwater sensitivity for a ten county area of south-central Kentucky relevant to a scale of 1: 24,000. The study area includes extensive limestone karst sinkhole plains, with groundwater that is generally extremely sensitive to contamination. Digitally Vectorized Geologic Quadrangles (DVGQs) were combined with elevation data to both identify hydrogeologic groundwater sensitivity regions and to identify zones of "high risk runoff where contaminants could be transported in runoff from …


Spatial Characteristics Of Paleochannels In Association With The Mississippian/Pennsylvanian Systematic Boundary In Western And South-Central Kentucky, Scott Schoefernacker May 2006

Spatial Characteristics Of Paleochannels In Association With The Mississippian/Pennsylvanian Systematic Boundary In Western And South-Central Kentucky, Scott Schoefernacker

Masters Theses & Specialist Projects

The basal Pennsylvanian Caseyville Formation of south-central Kentucky includes an extensive network of paleochannels, which unconformably overlie various Mississippian (Chesterian Series) rocks. Questions have been raised about the extent and orientation of paleochannels and the systemic boundary in the region. The problematical systemic boundary is quite significant in cases where marker beds are lacking or where sandstone facies of Pennsylvanian age are juxtaposed on lithologically similar Mississippian-age strata. Discerning the systemic boundary may also be complicated by facies changes in Chesterian strata. This study employs various data to investigate the Mississippian-Pennsylvanian systemic boundary such as well logs, outcrops, and subsurface-to-outcrop …


Late Pleistocene Climate Inferred From The Reconstruction Of The Taylor River Glacier Complex, Southern Sawatch Range, Colorado, Keith A. Brugger May 2006

Late Pleistocene Climate Inferred From The Reconstruction Of The Taylor River Glacier Complex, Southern Sawatch Range, Colorado, Keith A. Brugger

Geology Publications

Ice surface topography of a late Pleistocene glacier complex, herein named the Taylor River Glacier Complex (TRGC), was reconstructed on the basis of detailed mapping of glacial landforms combined with analyses of aerial photos and topographic maps. During the last glacial maximum (LGM), the TRGC covered an area of 215 km2 and consisted of five valley or outlet glaciers that were nourished by accumulation in cirques basins and/or upland ice fields.

Equilibrium-line altitudes (ELAs) for the glaciers of the TRGC were estimated using the accumulation-area ratio method, assuming that ratio to be 0.65 ± 0.05. ELAs thus derived ranged …


Lower Paleozoic Sequence Stratigraphy, Deposystems And Paleogeography Of Northwestern Ordos Basin, North China, Benjamin J. Kessel May 2006

Lower Paleozoic Sequence Stratigraphy, Deposystems And Paleogeography Of Northwestern Ordos Basin, North China, Benjamin J. Kessel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Ordos basin rests upon the North China Block and is one of the largest sedimentary basins in north China, with more than 15 km of Phanerozoic strata. Published estimates suggest that over 2000 m of carbonates and lesser amounts of siliciclastics were deposited on the North China Carbonate Platform (NCCP) from the Lower Can1brian through the Middle Ordovician. However, lower Paleozoic facies successions and deposystems of northwestern Ordos basin remain poorly represented in western literature. This paper constrains depositional environments, lithologies, facies relationships and sea-level history of the northwestern part of the North China block (NCB) in an effort …


The Evolution From Late Miocene West Salton Detachment Faulting To Cross-Cutting Pleistocene Oblique Strike-Slip Faults In The Sw Salton Trough, Southern California, Alexander N. Steely May 2006

The Evolution From Late Miocene West Salton Detachment Faulting To Cross-Cutting Pleistocene Oblique Strike-Slip Faults In The Sw Salton Trough, Southern California, Alexander N. Steely

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Field studies in the southwest Salton Trough between Yaqui Ridge and Borrego Mountain show that the West Salton detachment fault was active during the Pliocene and may have initiated during the latest Miocene. At Yaqui Ridge dominantly east-directed extension is recorded by slickenlines on the NW-striking detachment fault, and shows that the fault is actually a low-angle dextral oblique strike-slip fault. Crustal inheritance is responsible for the position of the fault at Yaqui Ridge, which reactivates a late Cretaceous reverse-sense mylonite zone at map scale.

Late Miocene to Pliocene basin fill deposits at Borrego Mountain display progressive unconformities, contain detritus …


Using Fill Terraces To Understand Incision Rates And Evolution Of The Colorado River In Eastern Grand Canyon, Arizona, J. L. Pederson, M. D. Anders, Tammy M. Rittenour, W. D. Sharp, J. C. Gosse, K. E. Karlstrom Apr 2006

Using Fill Terraces To Understand Incision Rates And Evolution Of The Colorado River In Eastern Grand Canyon, Arizona, J. L. Pederson, M. D. Anders, Tammy M. Rittenour, W. D. Sharp, J. C. Gosse, K. E. Karlstrom

Geosciences Faculty Publications

The incision and aggradation of the Colorado River in eastern Grand Canyon through middle to late Quaternary time can be traced in detail using well-exposed fill terraces dated by a combination of optically stimulated luminescence, uranium series, and cosmogenic nuclide dating. This fluvial history provides the best bedrock incision rate for this important landscape and highlights the complications and advantages of fill terrace records for understanding river long-profile evolution and incision. The use of fill terraces, as distinct from strath terraces, for calculating incision rates is complicated by the cyclic alluviation and incision they record. In the example of the …


2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla Apr 2006

2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla

Undergraduate Research Conference at Missouri S&T

No abstract provided.


Thermometric Measurements Of The Molecular Sublayer At The Air-Water Interface, B. Ward Apr 2006

Thermometric Measurements Of The Molecular Sublayer At The Air-Water Interface, B. Ward

OES Faculty Publications

[1] A series of measurements was conducted in the AirSea Interaction Saltwater Tank (ASIST) to study the response of the air-water interfacial molecular sublayer under various heat flux and wind speed conditions. In-situ gradients were measured with a platinum-plated tungsten wire microthermometer, which resolved the temperature of the thermally conductive sublayer. Air-sea heat flux was controlled by changing the air-water temperature difference (ΔTAW) and the wind speed, and measurements were made for three ΔTAW regimes over a range of wind speeds. A function was fitted to the measured temperature profiles as a way of extracting the boundary …


Competitive Effects Of Uranyl-Organic Complexes On U(Vi) Reduction By Shewanella Putrefaciens, Abraham M. Northup Apr 2006

Competitive Effects Of Uranyl-Organic Complexes On U(Vi) Reduction By Shewanella Putrefaciens, Abraham M. Northup

Masters Theses

Haas and DiChristina (2002) have demonstrated that Fe(III) reduction by the facultative Fe(III)-reducing bacterium S. putrefaciens is mediated by competitive speciation among dissolved organic ligands and functional groups on the cell surface. They also showed that rates of Fe(III) reduction by S. putrefaciens correlate with the thermodynamic stability constants of the Fe(III)-organic ligand complexes. S. putrefaciens can also use U(VI) as a terminal electron acceptor, coupling U(VI) reduction to growth. In this study, S. putrefaciens was incubated in experimental media containing U(VI) in the form of aqueous complexes with a variety of organic ligands that differ significantly in structure and …


Evaluation Of Geophysical And Thermal Methods For Detecting Submarine Groundwater Discharge (Sgd) In The Suwannee River Estuary, Florida, Matthew Weiss Mar 2006

Evaluation Of Geophysical And Thermal Methods For Detecting Submarine Groundwater Discharge (Sgd) In The Suwannee River Estuary, Florida, Matthew Weiss

USF Tampa Graduate Theses and Dissertations

Submarine groundwater discharge (SGD) represents a significant portion of the total discharge from coastal aquifers through diffuse seepage and point source springs, but can be difficult to locate. SGD is important as it can be a source of nutrients to estuaries and other coastal ecosystems. In an effort to evaluate geophysical and thermal methods for detecting SGD on the Florida Gulf coast, a suite of water-borne surveys were run in conjunction with aerial thermal imagery over the lower Suwannee River and estuary in March and September 2005. Thermal imagery exploits temperature differences between discharging groundwater and surface water. Thermal images …


Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric H. Christiansen, Bart J. Kowallis, Aaron J. Adams, Oscar Carranza-Castaneda, Wade E. Miller Mar 2006

Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric H. Christiansen, Bart J. Kowallis, Aaron J. Adams, Oscar Carranza-Castaneda, Wade E. Miller

Faculty Publications

The San Miguel de Allende graben, Guanajuato, Mexico, contains numerous rhyolitic volcanic ash beds. Electron microprobe and x-ray fluorescence analyses of glass shards from 14 localities, combined with mineralogic, stratigraphic, radiometric, and paleomagnetic data, allow us to correlate the ash beds (and the intervening sedimentary strata and fossils), understand the timing of volcanism, date the age of extension, and better understand the tectonic and volcanic evolution of central Mexico. Our analyses reveal that at least six separate eruptions of rhyolitic ash occurred during the Late Miocene and Pliocene (5-3 Ma) while the San Miguel Allende basin was subsiding. The fallout …