Fischer, Mark P.
M.S. (Master of Science)
Department of Geology and Environmental Geosciences
Lisbon Valley (Utah); Paradox Basin; Geology; Geology--Utah; Geology--Colorado
The Lisbon Valley Anticline is one of several NW-trending, salt-cored anticlines in the Paradox Basin of eastern Utah and southwestern Colorado. These structures formed when evaporites of the Paradox Formation were subjected to differential loading by southwestward- prograding sediment that was shed from the Uncompaghre Uplift during the Pennsylvanian to Jurassic. This study combines fieldwork with isotopic analysis of veins and host rocks, well-logs and seismic data to create an integrated interpretation of the architecture and origin of the fracture and paleofluid systems in the Lisbon Valley Anticline.;Seismic data indicate that the Lisbon Valley Anticline localized above four faults, one partially inverted normal fault and three normal faults that cut the underlying Mississippian basement. Although all four faults trend NW-SE, the eastern two faults appear to curve and terminate against the straight, westernmost faults, forming a complex relay structure. Passive diapiric growth of an elongate salt pillow above this basement structure initiated the salt-cored anticline, which was subsequently cut during Cenezoic extension by the northeast-dipping, listric, Lisbon Valley fault. Fieldwork reveals that there are three systematic fracture sets throughout the structure: one strike-parallel, one cross-strike, and one locally present strike-oblique set. Structural analysis and the absence of similarly oriented fractures in nearby flat-lying rocks suggests all of the fracture sets are related to the evolution of the Lisbon Valley structure. Veins are rare in the area, but carbon and oxygen stable isotopic results suggest veins formed from an external fluid source and that fractures played an important role in transmitting and compartmentalizing fluids in the suprasalt section. Structural modeling and strain analysis predict similar fracture characteristics to what was documented during fieldwork.
Fleming, Matthew W., "Integrated structural and fracture analysis of Lisbon Valley Salt Anticline, Utah" (2015). Graduate Research Theses & Dissertations. 3599.
Northern Illinois University
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