Preliminary basin analysis of late Proterozoic-Cambrian post-rift strata, southeast Idaho thrust belt
Strata of the Brigham Group in the Paris-Putnam plate of the southeastern Idaho thrust belt span the late Proterozoic-Cambrian boundary and consist of quartzose sandstone with subordinate pebble conglomerate and siltstone. The Brigham Group is overlain by fossiliferous Cambrian carbonate units that represent the transition from siliciclastic to carbonate deposition in the Cordilleran miogeocline. The Brigham Group contains four stratigraphic sequences bounded by regional disconformities. The lower sequence includes strata below the Brigham group (upper member, Pocatello Formation), plus the Papoose Creek Formation and most of the overlying Caddy Canyon Quartzite. This sequence is dominantly marine with shoreface and braided fluvial strata at the top. The first sequence is overlain disconformably by offshore sub-wave base marine strata of the upper Caddy Canyon Quartzite and Inkom Formation. This second sequence is entirely marine and is composed dominantly of siltstone with sandstone-filled channels. The third sequence comprises the Mutual Formation, an entirely braided fluvial and lacustrine unit. The fourth sequence (Sauk sequence) locally overlies the Mutual Formation with an erosional unconformity and consists of dominantly marine strata of the Camelback Mountain Quartzite, Gibson Jack Formation, Windy Pass Argillite, Twin Knobs Formation, and Sedgwick peak Quartzite. Correlations of these sequences to the McCoy Creek Group of eastern Nevada suggests uniform conditions of sea level and subsidence across the late Proterozoic-Cambrian Cordilleran miogeocline. This preliminary synthesis suggests the Brigham and McCoy Creek Groups are post-rift deposits, as indicated by regional persistence of facies, paleocurrents, and quartzose petrology.
- Research Organization:
- Idaho State Univ., Pocatello
- OSTI ID:
- 5863995
- Report Number(s):
- CONF-870915-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 71:8; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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020200* -- Petroleum-- Reserves
Geology
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CAMBRIAN PERIOD
CARBONATE ROCKS
CONGLOMERATES
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
IDAHO
NORTH AMERICA
PALEOZOIC ERA
PETROLEUM GEOLOGY
RIFT ZONES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SILTSTONES
USA