Physical Sciences and Mathematics Commons^™

When, How, And Why Did The West Antarctic Ice Sheet Retreat In The Ross Sea Since The Last Glacial Maximum Using Foraminiferal And Porewater Geochemistry, Matthew Decesare

LSU Doctoral Dissertations

The Antarctic Ice Sheets (AIS) began to retreat from their Last Glacial Maximum (LGM) position sometime after 19,000 years ago. However, the corrosive waters circulating around Antarctica has prevented the recovery of radiocarbon-dateable material, hindering the development of deglacial chronologies. During Expedition NBP1502B to the eastern Ross Sea, an unprecedented quantity of fossil foraminifera and bivalves were recovered. Radiocarbon-dated specimens have been used to constrain the timing of West-AIS retreat from Whales Deep basin and Ross Bank. Whales Deep samples show that the WAIS retreated from its LGM position on the continental shelf edge by 14,700 ± 400 calibrated radiocarbon …

The Role Of High-Elevation Headwater Runoff In Streamflow Generation And Water Supply In The Northern Andes, Colombia, Laura Lotero Lozano

USF Tampa Graduate Theses and Dissertations

Water security requires that sufficient quantities of water be available at critical times. This is particularly challenging for high-intensity urban and agricultural settings. In underdeveloped nations, streamflow is commonly the preferred water source, as it is readily available and delivered cost-free to users. Yet, the sources of these critical streamflows are often unknown. This issue is salient in the Northern Andes, where basic knowledge of controlling factors for the quantity, quality, and timing of runoff is lacking. High-elevation headwaters are the primary catchment areas in the Northern Andes, but the extent of water providing to municipalities in the Northern Andes …

Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee

Earth and Planetary Sciences ETDs

Volatiles (N2, CO2, and He) are released by volcanism and hydrothermal activity during continental rifting and subduction processes. Analyses of volatile components have been conducted to obtain gas contents (CO2, SO2, H2S, N2, Ar, He, and so on), stable isotope compositions (δ13C, δ15N, and so on), and noble gas isotopes (3He/4He, 40Ar/36Ar, and so on). This dissertation includes four chapters to report new nitrogen isotope fractionation factors of bubbling gases during gas-water transfer at various water temperatures (Chapter 1), first measurements of massive amounts of CO2 released by incipient continental rifting in the Magadi and Natron Basin, East African Rift …

Middle Miocene Paleoenvironmental Reconstruction Of The Central Great Plains From Stable Carbon Isotopes In Large Mammals, Willow H. Nguy

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

Middle Miocene (18-12 Mya) mammalian faunas of the North American Great Plains contained a much higher diversity of apparent browsers than any modern biome. This has been attributed to greater primary productivity, which may have supported greater browser diversity that commonly corresponds with densely vegetated habitats. However, several lines of proxy evidence suggest that open woodlands or savannas dominated middle Miocene biomes; neither of which support many browsers today. Stable carbon isotopes in mammalian herbivore tooth enamel were used to reconstruct vegetation structure of middle Miocene biomes.

Stable carbon isotopes in C₃ dominated environments reflect vegetation density and herbivores …

Hydrologic And Chemical Interaction Between Waste Dumps And A Flooded Mine Pool At The Combination Mine, Philipsburg District, Montana, Corey Swisher

Graduate Theses & Non-Theses

The Combination Mine, located approximately 12 miles northwest of Philipsburg Montana, was intermittently mined for silver, gold, and copper from 1885 until the 1990s. After the Combination Mine was formally abandoned groundwater seeps downgradient of the mine and waste rock pile were found to be above the regulatory water quality standards. Since the groundwater seeps were downgradient of both the mine pool and waste rock pile the source of the groundwater seeps could have been from the mine pool or shallow flow paths through the waste rock pile. In order to properly plan and execute a remedial action on the …

Supergene Mineralization Of The Continental Pit, Butte, Silver Bow County, Montana, Kyle Eastman

Graduate Theses & Non-Theses

The Butte porphyry Cu-Mo-Ag deposit has been considerably altered by supergene processes that enriched Cu and Ag, and mobilized other metals. Supergene enrichment provided early miners with excellent ore grades, and contributes significantly to current mining operations in Butte. The Continental Pit exhibits the classic leached and enriched vertical zonation that is common in near-surface porphyry systems around the world. Although studied by the Anaconda Copper Mining Company during the mid-20th century, significant and economically relevant questions remain regarding this deposit’s supergene heavy metal geochemistry and its relationship to the local hydrology and tectonic history.

This thesis investigates the paragenesis …

Petrographical And Geochemical Changes In Bosnian Stalagmites And Their Palaeo-Environmental Significance, Veronica Chiarini, Isabelle Couchoud, Russell Drysdale, Petra Bajo, Simone Milanolo, Silvia Frisia, Alan Greig, John Hellstrom, Jo De Waele

International Journal of Speleology

Detailed petrographic observations have been coupled with trace element and δ¹³C - δ¹⁸O analyses in order to investigate their dynamics in two Holocene Bosnian speleothems. The potential of this multiproxy approach in providing a means to extract palaeo-environmental information from stalagmites whose stable isotope signals are noisy and without obvious trends has been tested. The studied stalagmites are mostly characterized by columnar microcrystalline fabric. At the sub-millimetre scale of lamination, different microcrystalline columnar sub-types (open and closed) have been detected and classified on the basis of the observed porosity and the crystallite size. The presence of …

The Impact Of Eustasy, Tectonics, And Paleoclimate On The Dolomitization Of The Syn-Rift Neogene Carbonate Platforms In The Red Sea Coastal Area, Egypt, Abdallah Mohammed Hassan

Turkish Journal of Earth Sciences

A very significant quantity of dolomites and dolomitic limestones of variable origins occurs in the syn-rift Neogene carbonate platforms of the NW Red Sea coast and the Gulf of Suez. These are more common in the Um Diheisi Member of the Ranga Formation (early Miocene), the Um Mahara Formation (middle Miocene), the Um Gheig Formation (late Miocene), and the Dashet El Dabaa Member of the Shagra Formation (Pliocene). Based on their stratigraphic distribution, petrography, and cathodoluminescent characteristics, as supported by geochemical data, syn-rift irregular morphotectonic relief, and the eustasy, four distinct types of dolomites have been identified and were interpreted …

Evaluation Of Hydrogeochemical And Isotopic Properties Of The Geothermal Waters In The East Of Mount Sabalan, Nw Iran, Rahim Masoumi, Ali Asghar Calagari, Kamal Siahcheshm, Soheil Porkhial

Turkish Journal of Earth Sciences

The Mount Sabalan district is regarded as the best place to investigate geothermal activities in northwest Iran. Since the last episode of volcanic activity in the Plio-Quaternary time, hot springs and surficial steams as conspicuous manifestation of geothermal activities have appeared around the slopes of Mount Sabalan. The hot fluids circulating in this geothermal field contains anions chiefly of HCO3- and Cl-; however, SO42- content in some water samples is relatively high, imparting sulfate characteristics to such fluids. Geothermometric studies provided compelling evidence for estimation of the reservoir temperature (~150 °C) in the study areas. Thus, in this respect, the …

Gypsum, Calcite, And Dolomite Caprock Fabrics And Geochemistry From The Gypsum Valley Salt Diapir, Paradox Basin, Southwestern Colorado, Kevin Lerer

Open Access Theses & Dissertations

Caprocks are found on top of or in a lateral position relative to salt diapirs. The caprocks predominantly comprise sulfate minerals such as anhydrite or gypsum, which presumably accreted during the dissolution of salt from evaporite sediments. In some cases, the sulfate minerals are replaced by carbonate minerals, referred to as "carbonate caprock". Carbonate caprocks associated with salt diapirs are important because they can act as reservoirs or conduits for hydrocarbons, and because they can be easily misidentified as carbonate lithologies belonging to the stratigraphy of the sedimentary sequences adjacent to the diapir, which can jeopardize the accurate interpretation of …

Genesis Of Unique Carbonate Fans In A Pre-Salt Reservoir Analogue, Indio Mountains, West Texas, Andre Llanos

Open Access Theses & Dissertations

Hydrocarbon exploration in pre-salt sediments of rift basins on the South Atlantic Margin have proven to be successful major oil plays. Located on the western margin of the rift, the Brazilian pre-salt reservoirs of the Santos, Campos, and Espirito Santo Basins are hosted by lacustrine/marine-influenced carbonates that comprise laterally extensive, laminated microbialite facies. The Indio Mountains, located in West Texas, provide well-exposed outcrops of Lower Cretaceous marine and non-marine rift basin strata that can be considered a reservoir-analog to the South Atlantic Margin pre-salt facies. Of particular interest for hydrocarbon exploration are unique carbonate features that have been discovered in …