ESTIMATING TOPOGRAPHIC HEIGHTS IN THE PERMIAN WICHITA MOUNTAINS, OKLAHOMA

The Wichita Mountains of southwestern Oklahoma expose a preserved Early Permian tor-topography that is now being exhumed. Combining information derived from the local facies, the Post Oak Conglomerate, of the surrounding Leonardian Hennessey Shale with regional stratigraphic data, and with an understanding of how the tor topography was generated, allows us to constrain sizes, shapes, and heights of the Permian topographic elements.

The rocks of the Wichitas are Early Cambrian granites, rhyolites, and gabbros, and overlying Cambro-Ordovician limestones. The igneous rocks are the floor of the Cambrian Southern Oklahoma Aulacogen. These rocks were once buried 3-5km beneath the ancestral Anadarko Basin (Early to Mid Paleozoic "Oklahoma" Basin of Johnson). During Pennsylvanian uplift (i.e., Ancestral Rockies), structural relief of ~12km developed between the Wichita Uplift and the Anadarko Basin to the north. Substantial relief could have existed during this interval, but is entirely conjectural.

However, the Permian development of the tor topography on the granitic substrate requires a pre-existent, low-relief sub-horizontal surface, giving us a reference base. Uplift in the Early Permian and renewed erosion formed a new topography which was subsequently buried in Permian sediments. Relief of topographic highs on this topography reach 300-400m. Surrounding stratigraphy indicates these are probably also elevations.