Strain Partitioning in Foreland Basins

Abstract

We examined strain partitioning between the Ouachita fold-thrust belt and the Arkoma Foreland basin in southeastern Oklahoma and western Arkansas. The Choctaw Fault and Ross Creek Fault are the leading-edge thrusts of the fold-thrust belt and form the southern boundary of the Arkoma basin in Oklahoma and Arkansas, respectively. Strain portioning is accommodated by the Wilburton Triangle Zone in the footwall of the Choctaw Fault zone in Oklahoma. The triangle zone continues east towards Arkansas where the Choctaw Fault loses its separation and the Ross Creek Fault becomes the leading-edge thrust. Our structural interpretation of depth-converted 2-D seismic profiles and well log data in north-central Scott County, western Arkansas suggest the presence of a triangle zone containing the surficial tip-out of the Choctaw Fault in the footwall of the Ross Creek Fault. This triangle zone is named here the Waldron Triangle Zone and is composed of three stacked wedges that share a north-dipping roof thrust, which meets a south-dipping floor thrust at the tip line below the Poteau Syncline. Our interpretation of surface and subsurface geology suggests that the Waldron Triangle Zone continues along strike westward and coincides with its lateral equivalent, the Wilburton Triangle Zone.