Marine diatom biostratigraphy in Pacific Coast neogene basins
Marine diatoms offer a powerful tool for correlation in the Monterey Formation and related fine-grained siliceous rocks deposited in Pacific Coast basins during the late early Miocene (18 Ma) to the earliest Pliocene (4 Ma). In offshore regions, their biostratigraphic usefulness extends to the late Pliocene and Quaternary. In contrast to other microfossil groups, diatoms are abundant and diverse in cold waters, such as those that have typified the US pacific coast since 14 m.y. (latest Luisian benthic foraminiferal stage). Miocene diatom zones can be readily correlated throughout the North Pacific. Correlations with standard tropical microfossil zonations are well established, and an age resolution approaching 200,000-300,000 years is possible. Diatom frustules, however, are readily destroyed by diagenesis, so they are absent in the porcelanite and chert that typify most lower units of the Monterey Formation. In such circumstances, diatoms are commonly preserved in primary dolomites (beds and concretions), and diatom biostratigraphy can be applied.
- Research Organization:
- Geological Survey, Menlo Park, CA (USA)
- OSTI ID:
- 6835707
- Report Number(s):
- CONF-8804144-
- Journal Information:
- AAPG Bull.; (United States), Journal Name: AAPG Bull.; (United States) Vol. 72:3; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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Diatom biostratigraphy of chert intervals in Santa Maria and other Neogene basins, California
Updated diatom biostratigraphy for Monterey Formation