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Kerogen types and potential of source rocks of Cretaceous, Paleogene, and Neogene ages from western San Joaquin Valley, California

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:6931450

Ninety-two core samples of Cretaceous through Miocene rocks, from 13 wells in the western San Joaquin Valley, California, were examined in fluorescent light to assess kerogen types and source potential. The results are compared to those obtained from transmitted light analyses. Samples of different ages show more similarities than differences in kerogen types and source potential. The samples are mostly of fine-grained lithology from the Monterey, Kreyenhagen, and Moreno Formations, which are known or suspected source rocks in the San Joaquin Valley. All samples examined in this study are immature or marginally mature with respect to oil generation. Transmitted light analyses show that the organic matter of most of the samples consists of aggregated amorphous kerogen. Liptinitic (pollen, spores, cuticle, resin) and woody or coaly debris are generally minor components. Very finely divided amorphous kerogen is also present, usually in minor amounts. Based on the predominance of aggregated amorphous organic matter, most samples are interpreted to be oil prone. Fluorescent light analyses show that most of the organic matter consists of orange to brown-fluorescing Amorphinite B. Many samples also contain common to abundant amounts of yellow-fluorescing Amorphinite A. Liptinitic and nonfluorescing debris are generally less common. Grayish-fluorescing Amorphinite C is abundant to predominant in several samples in one well. Based on the predominance of Amorphinite B, most samples are interpreted to be oil prone. Additionally, most of the amorphous organic matter is interpreted to be of marine origin, probably derived from the decomposition of phytoplankton, zooplankton, and other marine organisms.

Research Organization:
Clark Geological Services, Fremont, CA
OSTI ID:
6931450
Report Number(s):
CONF-8604187-
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 70:4; ISSN AAPGB
Country of Publication:
United States
Language:
English