Petroleum Geology of Woodbine Formation, Freestone County, Texas
The Upper Cretaceous Woodbine Formation consists of clastics deposited in various southwestward-prograding environments on the margin of the subsiding East Texas basin. Depositional environments range from fluvial (in the north) to deltaic and a shelf strandplain (in the southwest). The Woodbine unconformably overlies the Lower Cretaceous Washita Group except in the basin axis and south of the Angelina-Caldwell flexure where deposition may have been continuous. Transgression by Eagle Ford seas closed the Woodbine deposition.
Structural features in Freestone County include the East Texas basin, the Sabine uplift, the Mexia-Talco fault zone, and the East Texas salt province. Isopach thicknesses of the Woodbine range from 375 ft in the west to more than 900 ft in the east (basinward). Thickening on the downthrown side of the Mexia-Talco faults indicates syndepositional faulting, related to allochthonous rocks sliding over the Jurassic Louann Salt.
Structural accumulations of petroleum have been discovered against faults and salt domes, but stratigraphic pinch-outs of the Woodbine's discontinuous lenticular sand bodies remain as excellent exploration opportunities.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.