Precambrian sedimentary rocks and associated mafic and silicic igneous rocks in Central Texas underwent a single episode of regional metamorphism about 1,050 million years (m.y.) ago. In the final stages of metamorphism great masses of granite and innumerable small pegmatite bodies intruded the older sedimentary and igneous rocks.

 In cooperation with several State and Federal agencies, the Bureau of Economic Geology has conducted several projects on the geology, origin, and extent of uranium resources in Texas. This volume, which was prepared in conjunction with a research colloquium sponsored by the Bureau, reviews and synthesizes the results of this research and demonstrates their applicability to the interpretation of uranium deposits.

Geologic map that depicts surface geology of parts of Hudspeth, Culberson, Jeff Davis, and Presidio Counties, Texas. The 12-page explanatory booklet indicates geologic formations, abbreviations, and ages.

Potential geopressured geothermal reservoirs in the Vicksburg Formation are limited to Hidalgo County along the Lower Texas Gulf Coast. In Hidalgo County, an area of approximately 385 square miles (designated the Vicksburg Fairway) contains up to 1,300 feet of geopressured sandstones with fluid temperatures greater than 300°F. Inplace effective permeability, however, averages less than 1 millidarcy in the Vicksburg sandstones because of fine grain size and extensive late carbonate cementation.