USING BALANCED STRUCTURAL CROSS-SECTIONS TO DETERMINE STRAIN PARTITIONING FROM THE CENTRAL OUACHITAS TO THE ARKOMA FORELAND BASIN, SOUTHEASTERN OKLAHOMA

The Arkoma basin, an arcuate structural feature located in southern Oklahoma and western Arkansas, is a foreland basin of the Ouachita fold and thrust belt. We have constructed many balanced structural cross-sections to determine the structural evolution of thrust faulting and the nature of strain partitioning from the central Ouachitas to the Arkoma basin. The cross-sections are based on the wire line logs of thousands of wells, available 2-D and 3-D reflection seismic data, and surface geologic maps.

In the Potato Hills area of the Central Ouachitas, the middle Ordovician to the Mississippian rock units are exposed at the surface. In the subsurface, however, the Choctaw detachment is the roof thrust of an antiformal stack structure which involves Pennsylvanian rock units. From the central Ouachitas to the leading edge of the frontal Ouachitas, strain partitioning is accommodated by imbricate fan thrusts on the hanging wall the Choctaw detachment. The strain partitioning is accommodated primarily by a triangle zone and associated duplex structure in the frontal Ouachitas-Arkoma basin transition zone where the Atokan turbiditic sequence is well exposed in both hanging wall and footwall of the Choctaw detachment. The duplex structure is located between the Springer detachment (the floor thrust) and the Lower Atokan detachment (the roof thrust) in the footwall of the Choctaw detachment. The triangle zone is floored by the Lower Atokan detachment and flanked by the Choctaw detachment to the south and the Carbon fault to the north. When restored to their original position prior to early Atokan time the cross-sections indicate about 60% shortening from the central Ouachitas to the Arkoma basin. The shortening is, however, only about 20% in the Arkoma basin in the footwall of the Choctaw detachment.