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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 69 (1985)

Issue: 4. (April)

First Page: 665

Last Page: 665

Title: Neogene Drape Folding Over Pre-Neogene Flexural-Slip Movements in Western Transverse Ranges, California: ABSTRACT

Author(s): A. Eugene Fritsche

Article Type: Meeting abstract

Abstract:

In several locations in the western Transverse Ranges of California are folded Neogene sedimentary sequences that unconformably overlie homoclinal sequences of pre-Neogene rocks. To accomplish the folding of the rocks above the unconformity without apparent deformation of those below the unconformity, a mechanism other than simple crustal shortening is required. It is proposed that differential flexural slip along bedding planes in the limbs of large-amplitude pre-Neogene folds produced drape folds of small amplitude in the unconformably overlying Neogene rocks. This drape mechanism implies that the Neogene rocks were folded while they were still in the soft-sediment stage and that they were lengthened parallel to bedding during the process. Procedures that use the length of folded beds to determine the amount of crustal shortening, therefore, may indicate a greater amount of crustal shortening than actually occurred.

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