A prograding margin model for the Monterey Formation, California
- Geological Survey, Menlo Park, CA (United States)
The Monterey Formation-a marine sedimentary deposit of Miocene (and locally Pliocene) age widespread in California, characterized by organic-carbon-rich fine-grained strata-is generally regarded as a classic petroleum source-rock resulting from high productivity linked with bottom-water anoxia. Current interpretations generally presume that the Monterey was deposited in steep-sloped isolated silled basins similar to modern Southern California Borderland basins, such that the stratigraphic sequence represents a [open quotes]pancake stack[close quotes] recording broad paleoceanographic changes neatly preserved in an anoxic bottom-water environment. Our review of evidence on the depositional setting, however, indicates a dynamic prograding margin, with facies highly controlled by local water depth and bottom configuration. We suggest that (1) Monterey strata were deposited on gentle slopes of broad irregular depressions along an open continental margin; (2) minor irregularities in bottom topography exerted major controls on facies, thicknesses, rates of silica dissolution, and ultimate accumulation rates of fine-grained sediment at a local scale; and (3) the large-scale facies sequences in most Monterey sections represent upsection shoaling (from 1500-1000m to 500-200m depths).
- OSTI ID:
- 6574114
- Report Number(s):
- CONF-960527--
- Journal Information:
- AAPG Bulletin, Journal Name: AAPG Bulletin Vol. 5; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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