Tectonic implications of the Dakota and lowermost Tropic formations, southwestern Utah
The middle Cretaceous (Albian-early Turonian) Dakota and lowermost Tropic formations in southwestern Utah form a wedge-shaped deposit of conglomerate, sandstone, mudstone, shale, and coal that thickens from a few meters in the Kaiparowits Plateau to more than 600 m in the Kolob terrace, a distance of 200 km. Four major facies assemblages are recognized: from the base upward, gravelly braided stream, coastal plain, mixed-energy shoreface, and offshore marine. The lowermost conglomerate unit was deposited by braided streams, that aggraded gravels within southeast-trending paleovalleys. A thin pebble lag occurs above and can be traced between conglomerate-filled valleys. The coastal-plain facies assemblage, characterized by fining-upward sandstone to coal sequences, was deposited by east-trending meandering streams with extensive interfluvial peat swamp and lacustrine environments. Five regionally correlatable (eustatic), transgressive-regressive marine sequences are recognized in the upper two facies assemblages, recording the initial incursion of the Cretaceous seaway. Temporally equivalent strata thicken from 8 m of offshore marine shale in the east to more than 200 m of stacked shoreline deposits in the west.
- Research Organization:
- RPI Colorado, Inc., Boulder
- OSTI ID:
- 7042398
- 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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011000 -- Coal
Lignite
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02 PETROLEUM
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Geology
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COAL DEPOSITS
COAL SEAMS
CONGLOMERATES
CRETACEOUS PERIOD
DEPOSITION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SILTSTONES
TECTONICS
USA
UTAH