Abstract: Southern Oklahoma Oil Country in Context of Plate Tectonics

Thomas L. Thompson

The Anadarko and Ardmore basins represent parts of the southern Oklahoma aulacogen, a Paleozoic tectonic complex that formed transverse to the ancient continental margin of North America. The aulacogen parallels Precambrian structural trends and extends at least 700 km (420 mi) into the Mid-Continent from its junction with the Ouachita foldbelt in southeastern Oklahoma.

The history of the southern Oklahoma aulacogen includes rifting, subsiding, and deforming stages with reasonable present-day analogies in the Afar region of east Africa (rifting), the Niger delta region of western Africa (subsiding), and the Timor Sea between Australia and Indonesia (deforming). Rifting affected much of North America about 550 m.y. ago and in southern Oklahoma perhaps occurred by right-slip extension as suggested by offset of the Grenville orogenic belt and the N60°W orientation of late Precambrian dikes. Silicic igneous activity followed mafic intrusions and extrusions. During the Late Cambrian through Early Devonian this igneous "basement" subsided below sea level and the aulacogen accumulated 5 to 10 times more marine sediment than adjacent areas, thus forming a structural trough buried with sediment about 10,000 to 15,000 ft (3,000 to 4,500 m) thick. Apparently guided by old normal faults, Devonian to Early Permian deformation included lateral as well as prominent vertical displacements, both reasonably explained by east-west compression related to plate convergence along the Ouachita orogenic belt.

Studies of southern Oklahoma that could lead to new discoveries of oil and gas include: (1) early Paleozoic relations among extensional faulting, sedimentation, magmatic heat, and fluid migration; (2) late Paleozoic structural style and sedimentation relative to remigration of early Paleozoic oil and gas accumulations; and (3) post-Paleozoic extensional fractures related to formation of the Gulf of Mexico.

AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma