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U.S. Department of Energy
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Tertiary basin-and-range structure in Southern Nevada-Utah-Arizona region via borehole, seismic reflection, and Bouguer gravity data: Insights on hydrocarbon potential

Conference ·
OSTI ID:6639206
Extension characterized by full grabens and half-grabens and tilted, folded, and faulted range blocks is geometrically and kinematically constrained by geologic and geophysical data. Rootless gravity-slide blocks are common secondary features to high-angle normal faults, which exert primary control over crustal extension. A synthetic seismogram from the only test well (Mobil Virgin River 1-A; TD = 5,962.5m), seismic reflection, and Bouguer gravity data (up to 70 mgal of relief) indicate over 7,600m of low-density Tertiary sediments in the Virgin Valley basin. Several thousand meters of sediment are within the oil-generative window. Neogene basalt flows suggest geothermal gradients higher than today. Lacustrine limestone in the Oliocene-Miocene Horse Spring Formation contains cryptalgalaminate, a potential hydrocarbon source. The Horse Spring Formation is overlain unconformably by the Miocene-Pliocene Muddy Creek Formation. These formations were deposited in association with movement on the Virgin-Beaver Dam Mountains fault, as indicated by fanning-upward reflector geometry. The formations are incorporated into a major rollover anticline. Mississippian Chainman Shale, penetrated to the west by Chevron's Colorock Quarry well, indicates a possibility for Sevier-age hydrocarbon generation by thrust loading.
OSTI ID:
6639206
Report Number(s):
CONF-880301-
Country of Publication:
United States
Language:
English