IDENTIFYING AND CORRELATING THE PENNSYLVANIAN ATOKA FORMATION SUBDIVISIONS IN THE SURFACE OUTCROPS OF THE BOSTON MOUNTAINS, ARKANSAS.

The surface outcrops of the Boston Mountains in northwest Arkansas are composed primarily of the Pennsylvanian Atoka formation. Where it is fully preserved in the Arkoma Basin to the south, the Atoka formation is greater than 5000m of sand and shale. However, it is undifferentiated in the surface geological map of Arkansas. This study investigates whether it is possible to identify and correlate the subdivisions of the Atoka formation in surface outcrops of the Boston Mountains. Until now, it has been difficult to subdivide and correlate Atoka subdivisions in surface outcrops using the standard correlation techniques of lithology and biostratigraphy. The subdivision of the Atoka has instead occurred in the subsurface in works by academia and the petroleum industry using wireline logging tools. These subdivisions are based on reservoir-quality sandstone cycles mappable throughout the basin. This study uses the first derivative of the USGS LiDAR elevation data (LiDAR Slope Map) and subsurface well-log correlations to identify and map the subdivisions, a previously unused mapping method for the Atoka. Before now, no widescale attempt has been made to identify the subsurface Atoka reservoir sandstone units in outcrop. When finished, the geological map of the subunits of the Atoka formation in the Boston Mountains will allow the geologist to see and touch what has, until now, only been studied using wellbore technology.