Dual mechanisms of Laramide structural growth: the Bighorn uplift-Powder River basin transition
The Bighorn uplift margin from Buffalo to Dayton, Wyoming, consists of a northern monoclinal domain and a southern fault-segmented domain. The Precambrian basement and overlying Paleozoic-Mesozoic strata have been rotated and folded in the monocline, producing a structural relief of 17,000 ft. Range-directed thrusts, formed by compression in the synclinal hinge of the monocline, are responsible for several second-order structures. The monocline may be transported eastward above a Rich-model thrust in the basement. The southern domain displays up to 20,000 ft of structural relief and consists of contiguous fault-bounded blocks with eastern margins 2 to 9 mi long. The largest and northernmost fault-bounded block, the Precambrian-cored Piney block, was transported eastward along a west-dipping reverse fault. Drilling indicates the fault overlies a vertical Cretaceous-Tertiary section underlain by nearly flat strata below the top of the Cretaceous Parkman Sandstone. Wells drilled through the Precambrian-cored Clear Creek thrust block west of Buffalo suggest a similar structural development. Reverse faulting in the southern domain occurred at a late stage, cutting through the synclinal flexure of the monocline, or occurred contemporaneously with the formation of the monocline to the north. Paleocene and Eocene syntectonic conglomerates underlie and front the range-bounding faults and exhibit basal angular unconformities. An arcuate band of conglomerates on the east side of Mowry basin implies the existence of other thrusts beneath Tertiary strata in the topographic basin, a conclusion reinforced by seismic data.
- Research Organization:
- Tenneco Oil Co., Bakersfield, CA
- OSTI ID:
- 6962952
- Report Number(s):
- CONF-8609129-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 70:8; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
CENOZOIC ERA
CONGLOMERATES
CRETACEOUS PERIOD
EXPLORATION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MESOZOIC ERA
MINERAL RESOURCES
MONTANA
NORTH AMERICA
PETROLEUM DEPOSITS
POWDER RIVER BASIN
RESOURCES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
TERTIARY PERIOD
USA
WYOMING