Topographically controlled ground-water-basin divides, established during the Pleistocene by erosion of the Pecos and Canadian River valleys, prevent ground-water recharge in the outcrop of the Triassic Dockum Group from entering the confined part of the aquifer in the Dockum Group beneath the Southern High Plains in the Texas Panhandle and eastern New Mexico. Ground water in the confined aquifer was probably recharged from precipitation at higher elevations in eastern New Mexico before thick deposits of Dockum Group sandstones were eroded.
Cores from deep stratigraphic test wells provide an excellent basis for determination of source-rock quality and thermal maturity of potential hydrocarbon source rocks in the Palo Duro Basin. Total organic carbon (TOC) content in Pennsylvanian and Wolfcampian rocks is highest in basinal shales. TOC values greater than 0.5 percent are common, which indicates that Palo Duro Basin shales contain sufficient organic matter to serve as source beds. Microscopic identification indicates that vitrinite, herbaceous material, and amorphous organic matter are the most abundant types of kerogen.
The San Andres Formation in the Palo Duro Basin is a middle Permian carbonate-evaporite sequence situated between two red-bed units, the underlying Glorieta and the overlying undifferentiated Queen-Grayburg sequences. The San Andres Formation, deposited during relative structural quiescence in the region, is composed of cyclic sequences of dark anhydritic mudstone, skeletal limestone, dolomite, nodular anhydrite, bedded anhydrite, and halite.
The State-owned submerged lands of Texas encompass almost 6,000 mi2 (15,540 km2). They lie below waters of the bay-estuary-lagoon system and the Gulf of Mexico and extend 10.3 mi (16.6 km) seaward from the Gulf shoreline (fig. 1). The importance of these lands and their resources to resident flora and fauna as well as to people is well known and documented; more than one-third of the state's population is concentrated within an area of the Coastal Zone that is only about one-sixteenth of the state's land area.