ABSTRACT

Detailed surface mapping in portions of Beckham, Custer, Roger Mills, and Washita Counties demonstrates that surface faulting and deformation previously ascribed to solution collapse is related to the subsurface faults in this portion of the Anadarko Basin. This conclusion is strengthened by Landsat (ERTS satellite imagery interpretations) studies which suggest that major lineaments are related to basement weakness zones which, by reactivation, are responsible for fracturing overlying sedimentary rocks.

The surface faulting appears to have been active at least from the Permian (Cloud Chief time) to the early Pleistocene. Evidences for movement in early Pleistocene include a downthrown block of Tertiary strata west of Elk City and factures that were contemporaneously filled with material of probable early Pleistocene age. Evidence for Permian movement includes fractures filled with Cloud Chief formation material.

The faulting appears to be related to the Wichita megashear fault system, the northwest trending faults being parallel to it, and the northeast trending faults, generally unrecognized, being oblique to it.

Clastic dikes are associated with the surface trace of the master subsurface faults. In the area where the Yelton Salt is known to be present in the subsurface, clastic dikes occur only along the fault traces. Collapse features due to the solution of the salt appear to have a spatial relationship to Cretaceous outliers, and may have a complex relationship with zones of weakness associated with the subsurface faults.