About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 548

Last Page: 549

Title: Entrapment Factors in California Turbidite and Canyon-Related Pools: ABSTRACT

Author(s): Gregory W. Webb

Article Type: Meeting abstract


California oil and gas pools in a variety of turbidite and other deep-water facies are classified according to their dominant or diagnostic causative geologic factors, some uniquely, others in more than one category. Canyon-dependent traps include sandstones in canyon walls and sandstones buttressed against canyon walls (Walnut Grove), sandstones draped by differential compaction over channel fill (Rosedale Ranch), and possibly other configurations. Fan-dependent stratigraphic traps are sand channels (and bar buildups?) without significant secondary structure (Strand). Anticline-dependent

End_Page 548------------------------------

traps include simple or braided sand sheets in younger anticlines (Ten Section) and more elusive narrow channel sands crossing such structures (Yowlumne). Fault-dependent pools with fault closure in fan sands include downdip block downthrown (English Colony), downdip block upthrown (Strand), possible downthrown rollover (Bellevue), and a postulated permeability barrier caused by strike-slip shearing (Coles Levee). Uplift bathymetry-dependent pools involve sands deposited against contemporary uplifted bathymetric highs, including basin-margin wedging (Saticoy), pinchouts of widespread sands against isolated uplifts (Paloma), and pinchouts of restricted channel sands against surrounding uplifts (26-R Elk Hills).

The scheme is intended to systematize model recognition in exploratory thinking rather than to generate unique pigeonholes. For example, bathymetrically restricted channel sandstones later upfolded to form traps may usefully be considered as anticline-dependent or as uplift bathymetry-dependent, and exploration for them may involve the search for channels in known anticlines (Yowlumne) or the search for anticlines along the postulated course of a channel sandstone (Asphalto).

End_of_Article - Last_Page 549------------

Copyright 1997 American Association of Petroleum Geologists