Rocks of the Ouachita facies are thrust out over the Arkoma basin. As expected, part of the crustal shortening is taken up in the Arkoma basin by folding parallel with the strike of the thrust faults. This shortening can be observed in the outcrops. Unfortunately, the intersection of the Ouachita front with the Arbuckle Mountains, the Ardmore basin, and the Marietta-Sherman basin is covered by the Cretaceous overlap. Therefore, the relation of the Ouachita facies with the Arbuckle facies can be determined only by subsurface information.

There is a regional southwest trend to the Ouachita front from where it disappears beneath the Cretaceous northeast of the Arbuckle Mountains to the Llano uplift in central Texas, indicating, in general, that the Ouachita facies was thrust from the southeast.

In the Ardmore and the Marietta-Sherman basins there are no indications of thrusting from the southeast. Rocks of the Ouachita facies are in contact with the Arbuckle facies by means of northwest-trending, high-angle reverse faults. The trend of folding in these basins is also northwest, with no northeast trending folding as one would expect in front of a thrust from the southeast. The Ardmore and Marietta-Sherman basins are characterized by large northwest-trending strike-slip faults. The best examples of these are the Reagan and Washita Valley faults which bound the Tishomingo uplift on the northeast and southwest, and the Mannsville-Madill-Aylesworth fault which parallels the Washita Valley fault.

It is concluded that in the Ardmore and Marietta-Sherman basins, the Ouachita facies is not in contact with Arbuckle facies by means of low-angle thrusting, but instead the Ouachita rocks have been shoved from the southeast in northwest-trending wedges. This action drove blocks of Arbuckle facies into confined spaces on the northwest and caused great crustal shortening along a southwest-northeast line resulting in the northwest trending structures of the Ardmore and Marietta basins.

End_of_Article - Last_Page 1822------------