Delaware Basin

The Delaware Basin is a geologic depositional and structural basin in West Texas and southern New Mexico, famous for holding large oil fields and for a fossilized reef exposed at the surface. Guadalupe Mountains National Park and Carlsbad Caverns National Park protect part of the basin. It is part of the larger Permian Basin, itself contained within the Mid-Continent oil province.

By earliest Permian time, during the Wolfcampian Epoch, the ovoid shaped subsiding Delaware Basin extended over 10,000 square miles (26,000 km²) in what is now western Texas and southeast New Mexico. This period of deposition left a thickness of 1600 to 2200 feet (490 to 670 m) of limestone interbedded with dark-colored shale.

A narrow outlet that geologists call the Hovey Channel periodically supplied new seawater from the Panthalassa Ocean to the west. The somewhat smaller and shallower Midland Basin was just east and the much smaller Marfa Basin was to the southwest. All three basins were south of the equator, north of the Ouachita Mountains of mid-Texas, and part of the northern continent Laurasia. Structurally the Delaware, Midland and Marfa were foreland basins created when the Ouachita Mountains were uplifted as the southern continent Gondwana collided with Laurasia, forming the supercontinent Pangea in the Late Carboniferous (Pennsylvanian). The Ouachita Mountains formed a rainshadow over the basins, and a warm shallow sea flooded the surrounding area. On the other side of the equator, the Ancestral Rocky Mountains formed a large mountainous island.

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