Lower Cambrian grand cycles of the southwestern Great Basin, U. S. A

Conference · Fri Feb 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5141545

Mount, J F; Hunt, D L; Dienger, J ^[1]; Green, L R ^[2]

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1. Univ. of California, Davis (United States)
2. Unocal Corp., Santa Fe Springs, CA (United States)

Depositional Grand Cycles are a prominent feature of Cambrian strata of western North America. Consisting of a lower siliciclastic half-cycle and an overlying carbonate half-cycle, these sequences appear to record regional deepening-shoaling events on a broadly subsiding Cambrian passive margin shelf. The Lower Cambrian Grand Cycles of the White-Inyo and Death Valley regions differ greatly from their Middle and Upper Cambrian counterparts throughout the Cordillera. These differences are manifested in the following ways: (1) Lower Cambrian siliciclastic half-cycles are relatively carbonate poor and were deposited primarily in deeper subtidal shelf settings; (2) siliciclastic half-cycle deposition is dominated by episodic storm processes, in contrast to the meter-scale, peritidal shallowing-upward cyclicity characteristic of younger Grand Cycles: (3) Grand Cycle boundaries are more diffuse and, in many cases, difficult to identify in more cratonward sections, and (4) trilobite zone boundaries appear to cross Lower Cambrian Grand Cycle boundaries appear to cross Lower Cambrian Grand Cycle boundaries, indicating that the cycles are not regionally correlative, unconformity bounded sequences. The depositional modeling indicates that these differences can be attributed to paleogeographic factors unique to the Early Cambrian. These include relatively rapid thermotectonic subsidence of the nascent Early Cambrian passive margin coupled with a high rate of eustatic sea level rise, high sediment yields off of the North American craton, and a relatively narrow Early Cambrian shelf.

• OSTI ID: 5141545
• Report Number(s): CONF-9103128--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CAMBRIAN PERIOD
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
GREAT BASIN
LEVELS
NORTH AMERICA
PALEOZOIC ERA
ROCKS
SEA LEVEL
SEDIMENTARY ROCKS
STRATIGRAPHY
TECTONICS
USA