Sedimentologic, stratigraphic, and paleoenvironmental study of Paleocene Fort Union Formation in South Cave Hills of Harding County, South Dakota

Conference · Fri Aug 01 04:00:00 EDT 1986 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6962850

Best, W A; Rich, F J

The Paleocene Fort Union Formation consists of the Ludlow, Cannonball, and Tongue River Members and forms prominent buttes in the Cave Hills, north-central Harding County, South Dakota. Investigations in the North Cave Hills show that cliff-forming Tongue River sandstones are actually the marine Cannonball Member. Field/laboratory studies indicate a similar reinterpretation for the cliff-forming sandstones in the South Cave Hills. These strata include fine to very fine-grained silty/clayey quartz sandstone. Textural analyses indicate the sand grains are subangular to rounded, polished, and of low to moderate sphericity. Sedimentary/biogenic structures indicate a high-energy, mainland beach/nearshore marine depositional environment. The transgressive sequence includes foreshore or littoral, shoreface, and subshoreface or estuarine environments. Foreshore/littoral sediments consist of fine to very fine-grained, moderately well to well-sorted, low-angle wedge planar and wedge trough cross-bedded sandstone. Trace fossils are dominated by Skolithos-like burrows. Marine vertebrate remains include Elasmobrachii sp., Myliobatis sp., and Myledaphus sp. Shoreface deposits are similar to those of the foreshore. Sedimentary structures are dominantly low- and high-angle wedge trough cross-beds. Ophiomorpha burrows occur near the upper contact. Shoreface deposits are separated from the subshoreface deposits by extensively burrowed silty sandstone or an erosional surface. The subshoreface environment produced very fine-grained sandstone interbedded with clay-claystone and clay shale that is very thin to thin bedded with minor amounts of ripple lamination and low-angle cross-stratification. Pseudo-symmetrical and composite ripples; flaser, wavy, and lenticular bedding; and sand-filled trails and burrows are present.

• Research Organization: South Dakota School of Mines and Technology, Rapid City
• OSTI ID: 6962850
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:8
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
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Geology
& Exploration
CENOZOIC ERA
DEPOSITION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
NORTH AMERICA
RESERVOIR ROCK
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SEDIMENTATION
SOUTH DAKOTA
STRATIGRAPHY
TERTIARY PERIOD
USA