LATE PALEOZOIC PALEOGEOGRAPHY AND TECTONICS OF THE GREATER PERMIAN BASIN AND ADJACENT ANCESTRAL ROCKY MOUNTAINS

The Greater Permian Basin (GPB) occupied a position between the Ancestral Rocky Mountains (ARM) and the Ouachita-Marathon (OM) orogenic system was influenced by both systems. The GPB evolved in the Pennsylvanian and Permian from the earlier Paleozoic Tobosa Basin. Unlike the earlier basin, the GPB was tectonically partitioned during much of its history into the Midland, Delaware, and Valverde basins. Especially during the Permian, these three basins have distinctive stratigraphic packages that reflect their linking to different tectonic elements.

The complex tectonic and sedimentologic events are not synchronous across the study area and are best shown on a series of paleotectonic and paleogeographic maps that display the geologic history of individual basins during the Penn-Perm and the relations of the basins to regional and adjacent tectonic elements. The Gondwana supercontinent approached SE North America and the resulting collision/accretion of Gondwana terranes generated the Late Mississippian-Early Permian OM orogenic belt and its foreland basin. The GPB reflects nearly continuous subsidence during this event; however, only the south and southeast margins of the basin received significant sediment from the orogenic belt. To the north, the uplifts of the ARM, many of which were active at differing times, supplied coarse sediment to the north and west margins of the GPB; the Central Basin Platform that separated the Midland and Delaware basins fed clastic sediment into both basins. Much of the deepwater sediment that dominates the Delaware and Midland basins was northerly derived, especially during the Wolfcampian and early Leonardian. Throughout the Penn-Early Perm, glacial-caused cycles were superimposed on stratigraphic events. Tectonic quiescence and regional subsidence dominated most of the region from Leonardian through Ochoan. Fine-grained redbeds formed as great volumes of loess spread across the region from the north; salt and carbonate accumulated along and within restricted seas as Permian sea level fell.

The region is significant, not only as a top 10 global petroleum province, but also as a major biostratigraphic region for the global Permian. It also provides the best window through which to evaluate the geologic history of the southern margin of Laurentia during the late Paleozoic.