SEDIMENTOLOGICAL AND HYDROGEOLOGICAL CHARACTERIZATION OF THE ANTLERS FORMATION AND AQUIFER IN SOUTH-CENTRAL OKLAHOMA

Because of its high permeability and adequate recharge, the Antlers is an important aquifer in Southeastern Oklahoma. The Cretaceous age Antlers Formation is the primary formation comprising the aquifer. It has been interpreted as a deltaic sequence dominated by sands with clay-rich zones and occasional conglomeritic and limestone-rich intervals. Sedimentological and hydrogeological studies of the Antlers are limited, with the most recent being a 1992 study to simulate ground water flow in the subsurface. The objective of this research is to better characterize the sedimentology of Antlers outcrops in Carter, Marshall, and Johnston County. By establishing the physical characteristics of the formation in outcrop, we hypothesize that observations of the rocks on the surface can be used to better model the heterogeneity of the aquifer in the subsurface. Outcrops will be described, sampled, and analyzed for grain-size distribution and composition. Samples from the region will be used to map distribution and spatial variability of various lithologies and sedimentological or hydrogeological characteristics, such as sand content and hydraulic conductivity. After correlating outcrop and borehole characteristics from water and oil/gas well logs, the mapping and spatial variability will be extended into the subsurface.