27 Late Paleozoic Intraplate Deformation of Central North America

Friday, 14 March 2003
1:00 PM - 5:00 PM

ESTIMATES OF PERMIAN TECTONISM IN THE WICHITA MOUNTAINS AREA

Paper number: 27-4
Program: THEME SESSIONS
Time: 2:00 PM – 2:20 PM

Authors

Abstract

The last stages of localized, Late Paleozoic uplift in the Wichita Mountains of southwestern Oklahoma, related to Ancestral Rockies Deformation/Ouachita Collision Event, can reasonably be inferred. Utilization of distribution of paleotopography, of unconformity characteristics, and of offset of lithologies leads to the following estimates of uplift and deformation in the Early Permian: vertical uplift of ~700 m (described in this presentation), and horizontal offset along the Meers Fault of ~several kms (from studies of Donovan). This contrasts with the main deformation in the Pennsylvanian where the Wichita Mountains block was uplifted ~7 km (described here) and horizontally offset by ~10-15 km (documented by McConnell). Thus there is about an order of magnitude difference between the main phase of deformation and that which occurred at the end of the deformation sequence in the Late Paleozoic.

The interesting aspect of this deformation sequence is that the final phase can be documented as occurring as a descrete phase because of the nature of some of the Permian stratigraphic units surrounding the Wichitas. This story hinges on understanding the Post Oak Conglomerate and its origin. The other interesting aspect of this last part of the deformation sequence is that the offsets cannot be due to passive effects, such as "settling" or compaction in the deep Anadarko Basin, because there is a distinct vertical component of uplift that simple subsidence to the north in the basin cannot explain. Far-field stresses would seem to be necessary.