Deltaic deposits of the Upper Cretaceous Dad Sandstone Member of the Lewis Shale, south-central Wyoming

Journal Article · Thu Jan 01 00:00:00 EST 1987 · Mt. Geol.; (United States)

OSTI ID:5637528

Perman, R C

The Dad Sandstone Member is a prograding unit of sandstone and minor mudstone that separates upper and lower shale members of the Lewis Shale. Outcrops of this Maestrichtian-age unit have been examined in south-central Wyoming along the eastern margin of the Great Divide basin north of Rawlins, and in the Hanna basin to the east. These outcrops form two groups with very different characteristics, including thickness of sandstone and interbedded mudstone units, sedimentary structures, and fossils. In the western part of the area studied, the Dad Sandstone is interpreted to represent progradation in the lower delta-front region of the Sheridan delta that existed to the northwest. In the eastern portion of the study area the Dad Sandstone probably represents upper shoreface facies of interdistributary barrier bars. These deposits may be related to either the Sheridan delta to the north, or a north-trending uplift to the south. The Dad Sandstone in the eastern part of the study area is probably slightly younger than in the western part of the study area.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 5637528
• Journal Information: Mt. Geol.; (United States), Vol. 24:1
• Country of Publication: United States
• Language: English

Related Subjects

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GEOLOGIC MODELS
RIVER DELTAS
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