Surface Geophysical Data Used for Mapping the Top of the Dockum Group on Cannon Air Force Base in Curry County, New Mexico, 2020

The hydrogeology of the Cannon Air Force Base (AFB) in Curry County, is being investigated to better understand the mechanics of groundwater flow in the area, including the identification of preferential groundwater flow paths. Mapping the top of the Dockum Group was done to help identify potential paleochannels that may have eroded the surface of the Dockum Group and subsequently filled in with coarse-grained sediments of the overlying Ogallala Formation. The Dockum Group is composed of sandstone, siltstone, mudstone, and shale that were originally deposited in fluvial and lacustrine environments (McGowen and others, 1979). The upper part of the Dockum Group is a thick layer of red clay referred to locally as the "red beds" and is a confining unit between the Ogallala aquifer and the Dockum aquifer. The lower part of the Ogallala Formation consists of heterogeneous sequences of gravel and coarse-grained sand that grades upward into sand, silt, and clay (Peckham and Ashworth, 1993). Paleochannels in the top part of the Dockum Group are believed to be preferential flow paths for groundwater in the area. The U.S. Geological Survey (USGS) in cooperation with the U.S. Air Force Civil Engineer Center (AFCEC) used surface geophysical resistivity methods to analyze the subsurface hydrogeology and map potential paleochannels within the Dockum Group, which can further aid in the understanding of the groundwater flow beneath Cannon AFB. This data release contains the results of 60 time-domain electromagnetic (TDEM) soundings and two electrical resistivity tomography (ERT) profiles collected on the AFB that will be used map the top of the Dockum Group.