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Item Use of geothermal bridge deck deicing systems to mitigate concrete deterioration in Montana(Montana State University - Bozeman, College of Engineering, 2023) Turner, Ethan Joseph; Co-chairs, Graduate Committee: Kirsten Matteson and Mohammad KhosraviReinforced concrete bridge decks face deterioration from thermal stresses, frost action, and early-age cracking. This thesis presents experimental testing and numerical simulations on a bridge deck deicing system's ability to mitigate concrete deterioration. Two experimental bridge deck models were constructed with embedded heat exchanger tubing and instrumented with thermocouples and strain gauges. The models were tested in a cold chamber laboratory under conditions representative of Montana winter weather. The experimental results suggested that a bridge deck deicing system with an inlet temperature of 8 °C shows promise in deicing, reducing thermal movements, and mitigating early-age cracking through thermal shrinkage. The temperature and strain results of the experiment were used to validate a numerical model constructed in COMSOL Multiphysics. Inlet fluid temperatures of 10 °C and 50 °C, chosen from common ground temperatures in Montana, were tested to evaluate the system's effect on frost action and thermal stresses. With a 10 °C inlet fluid temperature, the system showed promise in deicing and mitigating concrete deterioration. While the system did not always raise the surface temperature above 0 °C, the consistent increase in temperature suggested that under certain weather conditions, the system could keep the top surface temperature above 0 °C for a longer period than with no system. The system was also successful in reducing the range of strain due to thermal movements. The system was not able to mitigate the effects of frost action or temperature gradients. The temperature gradients induced by the system were at times worse than without the system, but the difference was insignificant. With a 50 °C fluid temperature, the system was more effective in deicing and mitigating frost action. The range of strain from thermal movements was also reduced more than with a 10 °C inlet fluid temperature. The thermal gradients, however, were at times slightly greater than design gradients provided by design specifications. The excessive gradients, however, only occurred during extreme weather conditions that are less common in Montana. While not perfect, geothermal bridge deck deicing systems show promise for mitigating some mechanisms of concrete deterioration, while keeping other mechanisms within allowable limits.Item Orogens of Big Sky Country: reconstructing the deep-time tectonothermal history of the Beartooth Mountains, Montana and Wyoming, USA(Montana State University - Bozeman, College of Letters & Science, 2021) Ronemus, Chance Baylor; Chairperson, Graduate Committee: Devon A. Orme; Devon A. Orme, William R. Guenthner, Stephen E. Cox and Christopher A. L. Kussmaul were co-authors of the article, 'Orogens of Big Sky Country: reconstructing the deep-time tectonothermal history of the Beartooth Mountains, Montana and Wyoming, USA' submitted to the journal 'MDPI Geosciences Special Issue: Evolution of Modern and Ancient Orogenic Belts' which is contained within this thesis.The southwestern Montana region has experienced a protracted history of orogeny, burial, and erosion recording the development of the western margin of Laurentia, the core of the North American continent. This > 2.5 Gyr record contains clues about the nature of Precambrian tectonism, the development of economic mineral and hydrocarbon reserves, and the long-term geodynamic evolution of Earth. However, aspects of this history remain enigmatic, with events in the geologic record obscured by erosion and thermal overprinting. The manuscript presented herein, bound by introductory and concluding chapters, comprises a deep-time thermochronologic investigation of the Beartooth Mountains. New biotite 40 Ar/39 Ar, and zircon U-Pb and (U-Th)/He data are presented from 14 samples collected from the Montana part of the range. These data indicate that thermal effects of Paleoproterozoic thermotectonism associated with the Big Sky orogeny (ca. 1.8-1.71 Ga) and/or related mantle metasomatism or mafic underplating penetrated into the core of these mountains. Thermal history model results indicate that this region of the craton experienced multi-phase Proterozoic cooling. The first phase of this cooling is generally coeval with the collapse of the Big Sky orogen. A second phase of Proterozoic cooling culminated in the development of the Great Unconformity surface, across which > 2 Gyr is regionally 'missing' from the stratigraphic record. Constraints placing this latter phase between 1.4 Ga and 0.8 Ga preclude mechanisms predicting later Neoproterozoic-Cambrian cooling, such as erosion associated with Snowball Earth glaciation, and support diachronous development of the Great Unconformity surface in Laurentia. Thermal models resolve a Phanerozoic thermal history involving maximum burial temperatures by late Pennsylvanian time and cooling throughout Mesozoic time. This Phanerozoic thermal history, broadly out of sync with nearby basins, underscores the effects of interactions between far-field tectonism and inherited crustal weaknesses in the Beartooth Mountains and reconciles previous interpretations of pre-Late Cretaceous cooling with other evidence only constraining later phases of uplift. Finally, model results suggest Cenozoic reheating--likely due to burial by volcanics--and later cooling to surface temperatures due to erosional removal of these rocks--potentially related to encroachment of the Yellowstone hotspot and/or regional Basin and Range extension.Item Geothermal systems of the Corwin Springs-Gardiner area, Montana : possible structural and lithologic controls(Montana State University - Bozeman, College of Letters & Science, 1976) Struhsacker, Eric MitchellItem The geology and geothermal potential of the upper Madison Valley between Wolf Creek and the Missouri Flats, Madison County, Montana(Montana State University - Bozeman, College of Letters & Science, 1976) Weinheimer, Gerald JosephItem The Structural, volcanic, and hydrothermal geology of the Warm Springs Creek Area, eastern Garnet Range, Powell County Montana(Montana State University - Bozeman, College of Letters & Science, 1984) Callmeyer, Thomas J.Item Hydrogeology and geothermal potential of the Radersburg Valley, Broadwater County, Montana(Montana State University - Bozeman, College of Letters & Science, 1984) Wyatt, Glen MiltonItem Qualitative hydrogeologic model of thermal springs in fractured crystalline rock(Montana State University - Bozeman, College of Letters & Science, 1977) Galloway, Michael J.Item Geothermometry of selected Montana hot spring waters(Montana State University - Bozeman, College of Letters & Science, 1974) Kaczmarek, Michael BernardItem Geology and geothermal system near Jackson, Beaverhead County, Montana(Montana State University - Bozeman, College of Letters & Science, 1983) Black, Geoffrey AlanItem Relationships among geochemical processes and microbial community structure in a unique high-arsenic, sulfidic geothermal spring in Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 2007) Taylor, William 'Peyton'; Chairperson, Graduate Committee: William P. Inskeep.The metabolisms of chemotrophic microorganisms are linked with the geochemical transformation of redox-active chemical species and mineral precipitation-dissolution reactions in geothermal environments. The objectives of the current work were to correlate the spatial distribution of microbial populations with changes in aqueous geochemistry and mineralogy in a unique Yellowstone National Park (YNP) geothermal spring, and to cultivate thermophilic microorganisms with phylogenetic and metabolic relevance to spring conditions. The geothermal spring (hereafter referenced as Joseph's Coat Spring -JC3) contains the highest reported concentrations of arsenic, antimony and thiosulfate of any geothermal feature studied in YNP. A suite of analytical and molecular approaches including aqueous geochemical and dissolved gas analysis, solid phase characterization, energetic calculations, microscopy and 16S rRNA gene sequence distribution were utilized to correlate specific microbial populations with biogeochemical processes. Predominant geochemical changes observed within the outflow channel were disappearance of methane, dissolved sulfide and ingassing of dissolved oxygen. Oxidation of arsenite was significant within the outflow channel despite the slow ingassing rates of dissolved oxygen. Microbial 16S rRNA gene sequences were determined at locations in the source pool and within the outflow channel.