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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 50 (1966)

Issue: 10. (October)

First Page: 2321

Last Page: 2321

Title: Foraminiferal Paleoecology and Paleoenvironmental Reconstruction of Oligocene Middle Frio in Chambers County, Texas: ABSTRACT

Author(s): Robert E. Gernant, Robert V. Kesling

Article Type: Meeting abstract

Abstract:

Middle Frio, here defined as material deposited from the time of Anomalina cocoaensis until the time of Nonion struma, has sedimentary rocks deposited in seven depositional environments in the subsurface of Chambers County, Texas: continental, brackish, saline bay, shallow inner shelf, deep inner shelf, middle shelf, and outer shelf. From the absence or abundance of various foraminiferal species, environments can be delineated by comparison of the Frio assemblages with the preferred distribution of living Foraminifera.

In Chambers County, eight persistent sandstone bodies can be recognized and correlated on the basis of seven foraminiferal chronologic indicators and of distinctive electric-log characteristics. Isopachous contour maps, incorporating thicknesses of sandstone bodies from approximately 400 electric-log sections, suggest depositional environments of the sandstone bodies.

The county is crossed by a system of middle Frio growth faults. Faunal analyses of sedimentary units indicate that topographic relief existed on the upthrown sides of the faults during deposition, and that turbidity currents periodically moved shallow-water sediments and their contained faunas to deep water on the downthrown sides.

Environments indicated on paleobathymetric maps, constructed from faunal analyses of 13 wells, correspond closely to the environments suggested by geometry of the sandstone bodies.

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Copyright 1997 American Association of Petroleum Geologists