Structural and Stratigraphic Transition from the Arkoma Shelf into the Arkoma Basin during Basin Subsidence; Arkoma Basin, Northwest Arkansas

The Arkoma basin is an arcuate Paleozoic structural feature in the Ouachita foreland that extends from central Arkansas and westward into southeastern Oklahoma. The Arkoma shelf lies immediately north of the basin and is comprised of Cambrian to Pennsylvanian age sedimentary rocks. In northwestern Arkansas, the stratigraphic and structural transition from the shelf into the northern portion of the Arkoma basin is poorly defined. Wireline logs were used to construct a series of three north to south cross sections, as well as two along-strike west to east cross sections to examine Morrowan and lower Atokan age strata. In addition to cross sections, isopach and structural contour maps were constructed from wireline log correlation. North to south cross sections display thickening to the south, particularly with sandstone and shale units. West to east cross sections exhibit thickening to the east due to proximity to an eastern terrigenous sediment source. Morrow and lower Atoka strata document the initiation of Arkoma basin subsidence during early Pennsylvanian time and reflect an eastern source of terrigenous sediment to the Arkoma shelf.