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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Structural Geology of Black Gap Area, Brewster County, Texas
By
University of Texas, M.A. thesis, 132 p., June, 1965
The outcropping strata of the Black Gap area are principally Cretaceous, but
include Tertiary volcanic rock and Quaternary alluvium. No rocks older than
the Cretaceous Glen Rose Limestone crop out within the map area, although
Paleozoic strata of the Ouachita System are exposed near the northwest corner.
The area is on the plunging northwest end of the Serrania del Burro and astride
the frontal and interior zones of the Ouachita System. To the north,
northwest-trending monoclines and an east-trending igneous belt border the
Marathon Basin; to the south lies the block-faulted and reverse-faulted eastern
margin of the Big Bend structural belt.
The mosaic of structural features is the result of several events. Uplift of
the Sierra del Carmen followed by decollement to the northeast across the Black
Gap area formed the asymmetric Stillwell anticline and other folds. Rejuvenation
of northeast-trending Paleozoic faults is probably the cause of the northeast -
striking Dove Mountain Ranch anticline and associated faults. The re-occurrence
of northwestward thrusting of the underlying Paleozoic strata, possibly resulting
from sub-crustal activity, compressed the strata, forming conjugate shear sets
striking approximately N. 20° W. and N. 75°W. in the massive Cretaceous
limestones. Release of compression resulted in block faulting along the zones
of weakness set up by the compression. A left-lateral rift movement accompanied
the normal faulting. End_of_Record - Last_Page 23--------