Geology Commons^™

The Effects Of Contact Metamorphism On The Host Rocks For Carlin-Type Mineralization At The Getchell Development, Nevada, Usa, Nathan C. Eck

UNLV Theses, Dissertations, Professional Papers, and Capstones

Carlin-type gold deposits (CTGDs) result from low to moderate temperature hydrothermal systems which form replacement bodies in carbonate or calcareous host rocks. The Getchell CTGD is located on the Getchell trend in north central Nevada. The Eocene age mineralization is locally hosted within the metamorphic aureole of the Cretaceous age Osgood stock. Previous studies have noted that the effects of the contact metamorphism can be heterogeneous, with strongly calc-silicate altered carbonates transitioning to relatively pristine limestone over short distances. The main finding of this study was that the variability in calc-silicate alteration is largely dependent on the differing host lithologies …

Physical And Chemical Properties Of Ice In A Main Valley Glacier And A Tributary Glacier, Gornergletscher, Canton Valais, Switzerland, Annika M. Quick

Theses and Dissertations

Glacier models often fail to incorporate the geometry and/or physical properties of tributaries included in complex glaciers. Tributary glaciers have different source areas and flow conditions than the adjacent main valley glacier. Ice cores (~3m depth) and surface samples (<0.5m depth) were collected from Grenzgletscher (main valley glacier) and Zwillingsgletscher (tributary glacier) in the Gornergletscher system of the Swiss Alps. Stable water isotopes indicate seasonal variation, showing 1-2 annual layers. The mean d18O for Grenzgletscher is ~4.8‰ lower than for Zwillingsgletscher. This difference may be accounted for in part by elevation differences between the accumulation areas (~1.1‰ δ18O), increased avalanching in Grenzgletscher (~1.8 ‰ δ18O), and by varying climatic conditions at the time of precipitation (~0.9-1.4‰ variation in δ18O). Using a kinematic ice flow model, core ages were estimated using effective annual layer thickness (based on seasonal variations), annual accumulation rate and ice thickness. The Grenzgletscher core is ~4 years older than the Zwillingsgletscher core. Based on ages and flow distances, the tributary has a lower flow velocity (63-87 m/yr) compared to Grenzgletscher (61-134 m/yr). To understand thermal properties of the tributary, a 775 m GPR survey (200 MHz) was conducted along a flow line of Zwillingsgletscher. Topographic waves (ogives) observed on the surface are mimicked by the onset of reflectivity 10-20 m below the surface. Reflective regions are interpreted as warmer ice at the pressure melting point, overlain by colder ice. This thermal structure is likely related to acceleration through an ice fall. Since most tributary glaciers include ice falls, thermal properties of tributary glaciers may be different from those of the main valley glacier. The properties and geometry of tributary glaciers are significantly different from main valley glaciers and should therefore be incorporated into glacier models in the future.

The Toll Of Toxics: Investigating Environmental Contaminants, Donald Sparling, Barnett A. Rattner, John S. Barclay

United States Geological Survey: Staff Publications

Two recent events [the Deepwater Horizon oil spill and the Asarco settlement] bring to the fore the work of wildlife toxicologists. Focusing on amphibians, reptiles, birds, and mammals, wildlife toxicology is a component of ecotoxicology--the study of toxic effects caused by natural or synthetic pollutants on living organisms and other constituents of ecosystems (Truhaut 1977). Now a distinct discipline within the wildlife profession-practiced by members of The Wildlife Society's own Wildlife Toxicology Working Group, among others-wildlife toxicology has become increasingly important as human populations and industry have spread, causing contaminants to multiply.

Emerging Environmental Contaminants (EECs) include an array of …

Quantifying Vertical Axis Rotation In Curved Orogens: Correlating Multiple Data Sets With A Refined Weighted Least Squares Strike Test, Adolph Yonkee, Arlo Brandon Weil

Geology Faculty Research and Scholarship

Map-scale curvature is a fundamental feature of most contractional orogenic belts and is central to understanding the kinematic and dynamic evolution of mountain systems. Paleomagnetic analysis, combined with detailed structural studies, is the most robust means of quantifying vertical axis rotations that produce curvature over a range of temporal and spatial scales. This paper explores how vertical axis rotations can best be evaluated for multiple data sets by applying a weighted least squares method to the classic strike test. This refined method provides measures of best fit slope, confidence interval, and goodness of fit between map-scale structural trend, paleomagnetic rotations, …

Sediment Flux Through The Rio Grande River: A Monsoonal Effect, Troy C. Hiatt

Theses and Dissertations

Climate has historically been recognized as an influence on sediment flux and deposition. The North American Monsoon is suggested as the forcing mechanism of deltaic progradational events of the Rio Grande River delta. Interpretations of reflection seismic profiles reveal that eustatic rise in sea-level from the Last Glacial Maximum to present is accompanied by several regressional events of the Rio Grande delta 5.5, 9.5, and 11.5 ka BP. Much of the migration of depositional facies within a delta system is forced by hinterland tectonics and base-level rise and fall. However, we suggest that the movement of facies within the Rio …

Variable-Density Flow Models Of Saltwater Intrusion In Coastal Landforms In Response To Climate Change Induced Sea Level Rise And A Chapter On Time-Frequency Analysis Of Ground Penetrating Radar Signals, Swagata Guha

USF Tampa Graduate Theses and Dissertations

Populations residing on and near the world’s coasts have become increasingly dependent on coastal groundwater for their supply of freshwater. Under the conditions of predicted climate changes, the expected rise in global sea level can adversely affect the quality and quantity of freshwater resources in coastal areas as a result of saltwater intrusion.

In this study, a suite of two- and three-dimensional variable-density groundwater flow models of major coastal landforms (e.g. deltas, estuaries and small islands) has been constructed to assess the effects of sea level rise (SLR), using different SLR rates of 0.5 m, 1m and 1.5 m over …

Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O8+Δ Mesas, Cihan Kurter, Lutfi Ozyuzer, Thomas Proslier, John F. Zasadzinski, David G. Hinks, Kenneth E. Gray

Physics Faculty Research & Creative Works

Anomalously high and sharp peaks in the conductance of intrinsic Josephson junctions in Bi₂ Sr₂ CaCu₂ O _8+δ (Bi2212) mesas have been commonly interpreted as superconducting energy gaps but here we show they are a result of strong self-heating. This conclusion follows directly from a comparison to the equilibrium gap measured by tunneling in single break junctions on equivalent crystals. As the number of junctions in the mesa, N, and thus heating increase, the peak voltages decrease and the peak width abruptly sharpens for N≥12. Clearly these widely variable features vs N cannot all represent the equilibrium …

Climatic Cycles Recorded In The Middle Eocene Hemipelagites From A Dinaric Foreland Basin Of Istria (Croatia), Borna Lužar-Oberiter, Peter A. Hochuli, Ljubomir Babić, Bosiljka Glumac, Darko Tibljas

Geosciences: Faculty Publications

Middle Eocene hemipelagic marls from the Pazin-Trieste Basin, a foreland basin of the Croatian Dinarides, display repetitive alternations of two types of marls with different resistance to weathering. This study focuses on the chemical composition, stable isotopes, and palynomorph content of these marls in order to better understand the nature of their cyclic deposition and to identify possible paleoenvironmental drivers responsible for their formation. The less resistant marls (LRM) have consistently lower carbonate content, lower δ18O and δ13C values, and more abundant dinoflagellate cysts than the more resistant marls (MRM). We interpret these differences between the two marl types to …

Glaciotectonic Deformation Along The Valparaiso Upland In Southwest Michigan, Usa, Brian C. Bird

Dissertations

Glaciotectonic deformation has been observed and analyzed across parts of the Valparaiso, Kendall, and Inner Kalamazoo Moraines in southwest Michigan, USA. Deformation structures such as folds and faults have been analyzed using techniques typically used by structural geologist along with the fabric of elongated clasts in the surficial diamicton. The structures are consistent with simple shear, horizontal compressional stresses, and pure shear. A series of drumlin fields exist along the western boundary of the study area. Direct investigation of the deformed sediments was conducted at a gravel pit in one of these drumlins. Lacustrine derived sediments interbedded with coarse sand …

Enrichments Of Heavy Sulfur (34s) In Sulfide Minerals: Gas Hydrates, Methane Delivery, And Anaerobic Methane Oxidation, Walter S. Borowski, Namcy M. Rodriguez, Charles K. Paull, William Ussler Iii

EKU Faculty and Staff Scholarship

The sulfur isotopic composition of authigenic, sedimentary sulfide minerals is largely controlled by sulfate reduction and related processes within sedimentary environments. Histograms show that that d³⁴S values of sulfide minerals forming in depositional and diagenetic environments are most often negative (d³⁴S < 0^o/_oo CDT) reflecting the original isotopic composition of seawater sulfate (now ~21^o/_oo), microbially-mediated fractionations of ~-8 to -40^o/_oo (a = 1.029-1.059) during sulfate reduction, and more extreme fractionations caused by sulfur disproportionation. Enrichments of heavy sulfur (d³⁴S > 0^o/_oo) in sulfide …

Mississippi Canyon 252 Incident Nrda Tier 1 For Deepwater Communities, Gregory Boland, Gary Brewer, Erik Cordes, Amanda Demopoulos, Chuek Fisher, Chris German, Ken Sulak

United States Geological Survey: Staff Publications

The northern Gulf of Mexico (GOM) is geologically diverse basin, described as the most complex continental slope region in the world. Regional topography of the slope consists of basins, knolls, ridges, and mounds derived from the dynamic adjustments of salt and the introduction of large volumes of sediment over long time scales. More than 99% of the sea floor in the GOM consists of soft sediment made up of various mixtures of primarily silt and clay. These wide-spread soft bottom communities are described in reports from major MMS studies by Gallaway et al. (1998) and Rowe and Kennicutt (2009). Relative …

Stratigraphy, Sedimentology, And Ichnology Of The Upper Cretaceous Frontier Formation In The Alkali Anticline Region, Bighorn County, Wyoming, Charles K. Clark

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Upper Cretaceous Frontier Formation was studied along two strike-parallel cliff-lines in the Alkali Anticline region of the northeastern Bighorn Basin, Bighorn County, Wyoming. The unit comprises up to 145 m of mudrock, sandstone, conglomerate, and volcanic fallout sediments deposited along the western margin of the Cretaceous Western Interior Seaway (KWIS) in the mid- to late-Cenomanian. Eighteen facies, comprising six facies associations are identified from physical and biogenic sedimentary features. Sediments were deposited in open marine offshore to shoreface and subaqueous deltaic to delta platform environments. The observed trace fossil suites record departures from the archetypal ichnofacies. Such departures record …

Establishment And Partial Characterization Of A Cell Line From Burbot Lota Lota Maculosa: Susceptibility To Ihnv, Ipnv And Vhsv, Mark P. Polinski, John D. Drennan, William N. Batts, Susan C. Ireland, Kenneth D. Cain

United States Geological Survey: Staff Publications

This study describes the development and partial characterization of a continuous fibroblastic-like cell line (BEF-1) developed from late stage embryos of North American burbot Lota lota maculosa. This cell line has been maintained for over 5 yr and 100 passages in vitro. Cells were cultured using Eagle’s minimum essential medium with Earle’s salts (MEM) supplemented with GlutaMAX ™, and 10% fetal bovine serum (FBS), pH 7.4. The addition of penicillin-streptomycinneomycin (PSN) antibiotic mixture (0.05, 0.05, 0.1 mg ml–1, respectively) did not negatively influence cell replication; however, the antimycotic Fungizone™ (2.5 μg ml–1, amphotericin B) caused cell rounding and …

Analysis Of Fresh Water Resources At The Line Hole Well Field, San Salvador Island, The Bahamas, Scot Allan Russell Jr.

Masters Theses & Specialist Projects

A major economic constraint in the Bahamas, and other small carbonates islands world-wide, is the lack of fresh water resources. To combat these socio-economic problems on San Salvador Island I sought to gain a more detailed understanding of the extent, behavior, and controls on the island’s fresh-water lens. DC electrical resistivity tomography and time-series geochemical data are used to study the fresh water lens at the Line Hole well field. Electrical Resistivity profiles are used to image the extent of fresh water resources. Time-series geochemical data provide information on the behavior of the fresh water resources as a function of …

Age And Isotopic Investigations Of The Olds Ferry Terrane And Its Relations To Other Terranes Of The Blue Mountains Province, Eastern Oregon And West-Central Idaho, Kyle P. Tumpane

Boise State University Theses and Dissertations

The Olds Ferry terrane of the Blue Mountains province is one of the numerous accreted terranes that comprise the western North American Cordillera. The Blue Mountains province is located in central and eastern Oregon, western Idaho, and extreme southeastern Washington, and is a crucial link in reconstructions of the North American Cordillera due to its position in an area with few visible terranes between the more extensively exposed terranes to the south in California and Nevada and to the north in Canada and Alaska.

New field evidence and U-Pb zircon geochronology for volcanics within the sedimentary onlap assemblages overlying the …

An Experimental Investigation Of Chemical Mass Transfer Processes In Crystallizing, Hydrous Silicate Magmas: The Genesis Of Ore Deposits And Metasomatic Fluids, Aaron S. Bell

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation is comprised of three broadly related experimental petrology projects on phase equilibria and noble metal solubility in hydrous silicate melts. Chapters two and three combine experimental petrology with high precision laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of experimental run products in order to quantitatively constrain the behavior of the investigated metals. Chapter four presents experimental evidence detailing a novel oxidation mechanism for degassing silicate liquids as well as exploring the geochemical consequences of the proposed mechanism.

Chapter two presents the results of an experimental study on Au, Pt, and Pd behavior in coexisting silicate melt-sulfide-oxide …

High-Resolution Holocene Alluvial Chronostratigraphy At Archaeological Sites In Eastern Grand Canyon, Arizona, Erin Margaret Tainer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Understanding the nature of Colorado River deposits in Grand Canyon helps reveal how the river responds to changes in its Colorado Plateau tributaries and Rocky Mountain headwaters. This study focused on Holocene alluvial deposits associated with archaeological sites excavated near Ninemile Draw in Glen Canyon and at Tanner Bar in eastern Grand Canyon. Two previously-developed conceptual models of deposition were tested based on previous work. Previous researchers have suggested that Holocene alluvial deposits in Grand Canyon are a series of inset aggradational packages that correlate to valley fills and arroyo-cutting cycles in Colorado Plateau tributaries and are laterally consistent throughout …

Bracketing The Age Of The Great Gallery Rock Art Panel In Horseshoe Canyon, Utah By Osl Dating Of Associated Alluvial Terraces, Melissa S. Jackson

Undergraduate Honors Capstone Projects

Barrier Canyon Style rock art (BCS) is a unique rock art style indigenous to the middle Colorado Plateau that is of an unknown age and formed by a combination of wall preparation, rock pecking, and application of multiple pigments. It is characterized by broad-shouldered, mummy-like figures that commonly lack limbs and facial details but are accompanied by animated and realistic representations of animals. The age of BCS art remains unknown in spite of attempts to radiocarbon date accessory brush fibers in the mineral-based pigment. Yet a range of age hypotheses exist, from as young as 1600 AD to as old …

Petrogenesis Of The Greenwater Range: Comparison To The Crater Flat Volcanic Field And Implications For Hazard Assessment, Ashley Kaye Tibbetts

UNLV Theses, Dissertations, Professional Papers, and Capstones

Pliocene basalts of the Greenwater Range, California erupted from 24 volcanic vents now represented by volcanic plugs, craters and scoria mounds. Basaltic magmas originated in the asthenospheric mantle, but show evidence of a lithospheric component. Depths and temperatures of melting calculated using a silica activity geobarometer are 54.3–89.6 km and 1367-1435oC, placing melting in the asthenosphere. The preferred petrogenetic model involves melting of lithospheric mantle thermally and mechanically, but not chemically, converted to asthenospheric mantle. Melting depths correspond to low velocity zones in the mantle as revealed in seismic profiles. Chemical and lithologic similarities between basalt in the Greenwater Range …

Phyllosilicate Mineralogy, 40ar/39ar Geochronology, And Genesis Of Petrocalcic Soils In The Southwest U.S.A., Colin R. Robins

UNLV Theses, Dissertations, Professional Papers, and Capstones

Obtaining isotope ages for arid soils and paleosols, including carbonate-cemented (calcic and petrocalcic) horizons, constitutes a significant challenge for soil scientists, geomorphologists, and stratigraphers. Carbonate-cemented soils foster diverse suites of authigenic minerals with exciting potential for geochronology, however, this potential has not been realized. This dissertation describes the timing of pedogenic palygorskite and sepiolite crystallization in extremely old, extant petrocalcic soils of the southwest U.S.A., and assumes that these fibrous, high-magnesium phyllosilicates contain sufficient lattice-bound K to warrant vacuum-encapsulated 40Ar/39Ar geochronology. This three-part study evaluated the (1) selective extraction, (2) 40Ar/39Ar analysis, and (3) pedogenesis of palygorskite and sepiolite.

Effects …