--> Abstract: Digital Compilation of Surface and Subsurface Geologic Data Across the Onshore-Offshore Transition in California: A New Project at the U.S. Geological Survey, by M. E. Tennyson; #90958 (1995).

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Abstract: Digital Compilation of Surface and Subsurface Geologic Data Across the Onshore-Offshore Transition in California: A New Project at the U.S. Geological Survey

Marilyn E. Tennyson

Framework geology of the innermost continental shelf in parts of California is poorly known, in contrast to the onshore, where mapping is fairly complete, and farther offshore, where stratigraphy and structure have been worked out in the petroleum leasing process. Consequently, seismic hazard, environmental, and resource issues are hard to evaluate. For example, the gap in published data landward of the three-mile limit made it difficult to closely constrain estimates of undiscovered petroleum resources in the State waters for the just-completed National Assessment of Oil and Gas Resources. Major faults lie near the boundary between the State and Federal offshore in several places. Mapping of these faults is fragmentary, and offset history and seismic potential remain unc rtain. Oil and gas seeps are locally numerous, but their locations have not been recorded in a format readily accessible to petroleum geologists, land managers, or environmental scientists.

A new project within the Energy Resource Surveys Program of the U.S. Geological Survey, in collaboration with other Federal and State agencies and with petroleum industry and academic scientists, will assemble existing but scattered data, compile surface and subsurface geologic data from onshore across the State waters into the Federal offshore, integrate it digitally, and construct a geologic synthesis. The project's focus is on areas adjacent to producing or prospective areas: off the Santa Monica and Santa Ynez Mountains, the Northern Channel Islands, the Santa Maria basin, and several areas in coastal northern California. Coastal onshore geologic contacts, onshore and offshore well locations and formation tops, seismic tracklines and interpreted faults, folds, and distributions an thicknesses of key stratigraphic units, and seep locations will be compiled. Data will be entered into ARC/INFO and released digitally, complemented by interpretive summaries for non-geologists. The data compilation will be useful for land management agencies, seismic hazard and environmental studies, and evaluation of petroleum resources and related issues.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California