| Popis: |
Areas of high electrical conductivity in shallow aquifers in the East Poplar oil field area (Figure 1) were delineated by the U.S. Geological Survey (USGS), in cooperation with the Fort Peck Assiniboine and Sioux Tribes to delineate areas of saline groundwater contamination. The generalized geologic section of the study area consists of electrically conductive glacial clays, more resistive sandy clays, and gravel units which are the most resistive. The glacial section, primarily east of the Poplar River (Figure 1), overlays a Cretaceous shale aquitard. West of the Poplar River, the shale is overlain in some areas by Tertiary sands and gravels and the glacial section is thin or absent. As part of this investigation, ground, airborne, and borehole geophysical data were collected in the area from 1992 through 2005 as part of an integrated hydrologic study. We present borehole geophysical data for thirty-two wells that were collected during, 1993, 2004 and 2005 in the study area. The well logs in 2004 and 2005 were collected to provide subsurface controls for interpretation of a helicopter electromagnetic survey flown over most of the East Figure 1 Location of the East Poplar Oil Field |
