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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 8. (August)

First Page: 1496

Last Page: 1496

Title: COCORP Deep Seismic Reflection Traverse Across Southern Oklahoma Aulacogen: ABSTRACT

Author(s): J. A. Brewer

Article Type: Meeting abstract


COCORP deep seismic reflection profiles across the width of the southern Oklahoma aulacogen, from the Hardeman basin on the south, through the Wichita Mountains and Anadarko basin on the north, reveal basement deformation that necessitates major revision of ideas about the geologic history.

The profiles south of the Wichita Mountains show that the Precambrian crust is highly layered to depths of 10 to 13 km over an area at least 2,500 km2, and probably much more. Judging by COCORP surveys elsewhere in the United States, such extensive Precambrian layering is very unusual. The layered crust can be interpreted as a large Proterozoic basin, probably filled mainly with clastic sediments and felsic volcanics since these lithologies are widespread in the Precambrian of the southern Mid-Continent region.

The layering is truncated on the south side of the Wichita Mountains, and under the mountains is either absent or only present in a highly altered form. The truncation is probably caused by Precambrian faults in conjunction with granitic intrusions. Pennsylvanian compression reactivated these faults.

The COCORP profiles across the northern flank of the Wichita Mountains and into Anadarko basin are in an early stage of processing, but preliminary results suggest that the Precambrian layering that is so distinctive south of the mountain does not extend beneath the Anadarko basin. Crystalline rocks of the Wichita Mountains appear to have thrust north along a moderately dipping fault, overlapping the basin by 8 to 9 km. The attitude of the fault at depth beneath the mountains is unclear at present.

Simple models for the southern Oklahoma area as an aulacogen must be revised to consider the complex Precambrian history revealed by the COCORP data.

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