Cambrian-Ordovician craton margin section, southern Great Basin: A sequence stratigraphic perspective
- California State Univ., Fullerton (United States)
- San Francisco State Univ., CA (United States)
The Upper Cambrian through Upper Ordovician cratonal to miogeoclinal transition section in southern Nevada and eastern California accumulated on a gentle homoclinal ramp and includes a variety of peritidal and subtidal carbonate facies. This section consists of a westward-thickening wedge assigned to the Nopah and Mountain Springs formations and can be related to one type 1 and least four type 2 sequences. The basal part of the section is the Dunderberg Shale Member of the Nopah Formation, which is composed of meter-scale cyclical shale-carbonate bundles. Carbonate interbeds signify a variety of peritidal to deep subtidal paleoenvironments that comprise shelf margin and transgressive systems tracts. The progradation of a thrombolitic bank complex in the overlying upper Nopah may reflect emergence on the craton, evidenced by the Sauk II-Sauk III cratonic disconformity. The overlying A' member of the Mountain Springs Formation rests in sharp and, in places, slightly discordant contact with the top of the Nopah. This contact is interpreted as a marine flooding surface and type 2 sequence boundary. Member A consists of Lower Ordovician transgressive and highstand systems tracts comprised of oolitic shoal and back-shoal to intertidal carbonates. The type 1 unconformity that separates member A from overlying B' member is the top of the first-order Sauk Sequence. The B' member is a thin stratal interval of late Middle to Late Ordovician age and consists of dark, burrow-mottled skeletal wackestone and mudstone that is part of a transgressive systems tract. It is bounded above by another type 1 unconformity and therefore represents the first-order Tippecanoe sequence of Sloss.
- OSTI ID:
- 5211472
- Report Number(s):
- CONF-9103128--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 75:2; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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