Style of deformation in productive fairway of Absaroka plate: southwest Wyoming and north-central Utah

Conference · Mon Aug 01 04:00:00 EDT 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6404237

West, J L

Deformation of the Absaroka plate is characterized by two subparallel trends which result from ramp anticlines. The western trend (anticline) is associated with truncation of the Paleozoic section against the Absaroka thrust, and the eastern trend (en echelon anticlines) with truncation of the Triassic/Lower Jurassic section. Variations in the style of folding are different on the two trends. This variation results from the vastly different mechanical properties of their stratigraphic sections; 4,500 ft (1,370 m) of nearly continuous, competent Paleozoic carbonate and quartzite produce a single ramp anticline 50 mi (80 km) long. Imbricate faults at the base of this anticline (western trend) cause oscillations of closure along strike and minor strike offsets. The eastern trend is dominated by folding rather than internal faulting. The Mesozoic section, which immediately overlies the thrust in the eastern trend, consists of alternating competent and incompetent units, each ranging from 750 to 2,500 ft (230 to 760 m) thick. Ramp anticlines develop from a single ramp through both competent units (producing one anticline) as well as stair-stepped ramps separated by a tread or glide plane in the incompetent unit between the Thaynes and Nugget formations (producing two anticlines). Additional folding may also result, apparently from simple compression which produces three anticlines stacked en echelon in the transport direction. Fold length along the eastern Mesozoic trend ranges from 1 to 6 mi (2 to 10 km). In contrast, oscillations in the 50-mi (80-km) long western anticline range from 5 to 15 mi (8 to 24 km).

• Research Organization: Anschutz Corp., Denver, CO
• OSTI ID: 6404237
• Report Number(s): CONF-8309274-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 67:8
• Country of Publication: United States
• Language: English

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03 NATURAL GAS
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58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
ANTICLINES
DEFORMATION
FEDERAL REGION VIII
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
NORTH AMERICA
PLATE TECTONICS
ROCKS
SEDIMENTARY ROCKS
STRATIGRAPHY
TECTONICS
USA
UTAH
WYOMING