Shallow-water and sub-storm-base deposition of Lewis Shale in Cretaceous Western interior seaway, south-central Wyoming

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:5968907

Winn, Jr, R D; Bishop, M G; Gardner, P S

Shallow- and deep-water (below storm base) clastics of the Lewis Shale were deposited in south-central Wyoming during a part of the Late Cretaceous Core, log, and outcrop data indicate that the Lewis Shale consists of a thin, transgressive, marine shale overlain by a thicker, coarser, progradational interval. The sea in which the Lewis Shale was deposited opened eastward into the North American Western Interior seaway. Shale in the lowermost Lewis is black, carbonaceous, bioturbated, and commonly contains shell debris and was deposited in shallow water. The central basin floor changed from shallow to sub-storm-wave and sub-storm-current depths, seemingly in response to eustatic sea level rise and coeval tectonic subsidence. Southwest progradation from a northeastern delta suggests significant uplift in the Wind River upthrust area concurrent with Lewis sedimentation. Many hydrocarbon-producing sandstones in the Lewis Shale are thickly bedded and massive, and some show fluid-escape structures. This sandstones are typically characterized by grading, Bouma sequences, and sole markings. Turbidity currents are believed to be responsible for deposition of all these sandstones. Unburrowed shale and shale containing burrows made by a restricted infauna are interbedded with reservoir sandstones at Wamsutter field. The shale is interpreted to indicate anaerobic to dysaerobic conditions and water depths of 500-650 ft (150-200m) or more.

• Research Organization: Marathon Oil Co., Littleton, CO
• OSTI ID: 5968907
• Journal Information: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 71:7; ISSN AABUD
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
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03 NATURAL GAS
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CRETACEOUS PERIOD
DEPOSITION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
LITHOLOGY
MESOZOIC ERA
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NORTH AMERICA
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
STRATIGRAPHY
USA
WYOMING