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The AAPG/Datapages Combined Publications Database

GCAGS Transactions


Gulf Coast Association of Geological Societies Transactions
Vol. 4 (1954), Pages 11-18

Stratigraphy of the Wilcox Sands of Zapata County, Texas

Jas. G. Joyce (1)


The Wilcox sands of Zapata County, Texas, are of interest because recent deep wells have added to our knowledge of stratigraphic changes, and recent oil and gas discoveries indicate economic importance. These sands are Early Eocene in age. From the outcrop in Tamaulipas, Mexico, where they are massive, cross-bedded, ripple-marked lignitic sandstones, they dip eastward underneath Zapata County at an average rate of 320 feet per mile. In central and eastern Zapata County, the Wilcox is made up of fine-grained subrounded sand beds separated by gray and brown pyritic shales. Generally, these sands are "tight", however, evidence shows that sufficient permeability and porosity do exist in some sands for commercial production. New sand-fracturing techniques have proved to be successful in these sands.

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