12 The Permian of the Southwest II

Friday, 12 April 2002
1:30 PM - 3:10 PM

HOW HIGH WERE THE PERMIAN WICHITA MOUNTAINS OF OKLAHOMA?

Paper number: 12-4
Program: SYMPOSIA SESSIONS
Time: 2:30 PM – 2:50 PM

Authors

Abstract

The Wichita Mountains of southwestern Oklahoma consist of Lower Cambrian igneous rocks, exposed basement of the Southern Oklahoma Aulacogen (SOA), and of Lower Paleozoic carbonates (Slick Hills area) that were deposited on the igneous rocks. As current denudation proceeds, the more resistant igneous rocks and carbonates form the rugged topography while the softer Lenardian siltstones (Hennessey Group and interfingering Post Oak Conglomerate (POC)) form the surrounding plains. The protruding older rocks represent a Permian topography that is being uncovered. Some interesting observations follow:

1)4-5km of Upper Cambrian to Mississippian strata were removed from SOA basement during Pennsylvanian uplift. 2)~750m (average) of Permian encased this paleotopography. 3)The POC sits about midway in this ~750m section and contains clasts of granite that attained their shape from spheroidal weathering before local transport. 4)Such weathering implies a previous very low relief landscape (weathering rates greater than erosion rates). 5)~300-350m of uplift and relief is needed to release these weathered boulders and to deposit the POC (erosion rates greater than weathering rates). This event is the last recorded Permian tectonism in this area. 6)~2000m of Permian on SOA basement occurs in a few places. Whether this could represent topography is debatable.