Application of Near-Surface Geophysical Techniques for Geologic and Hydrologic Investigations in the Arctic
A.J. Delaney (U.S. Army Cold Regions Research and Engineering Laboratory), P.R. Peapples (Alaska Division of Geological & Geophysical Surveys), and S.A. Arcone (U.S. Army Cold Regions Research and Engineering Laboratory)
Application of geophysical techniques for shallow sub-surface (0.5 to 30 meters) investigations in arctic Alaska is often challenging. The thin, saturated, active layer can greatly limit signal penetration; coarse-grained alluvium can scatter high-frequency pulses and perennially frozen sediments often demonstrate little contrast in electrical properties or density. Despite these challenges there are several situations, in the terrestrial Arctic, where ground penetrating radar (GPR) and electrical resistivity (DC) methods can be used effectively. Here we show results from several successful investigations that demonstrate the ability of geophysical tools to resolve and profile sediments layers, define taliks and thaw zones, and characterize bedrock structure. On an Itkillik River point bar deposit we used GPR to reveal sediment layering and depositional patterns. In a late winter study on the Sagavanirktok River, also using GPR, we detected the presence of thaw bulbs and frost taliks and confirmed our interpretation by drilling. During the winter we operated GPR, from low- flying helicopters, to locate sources of fresh water beneath continuous ice cover on rivers and streams east of Prudhoe Bay. Additionally in sub-arctic Alaska we have successfully used DC methods to identify bedrock fracture zones beneath sediment deposits. Our results demonstrate effective application of GPR and DC methods as tools to aid both geologic mapping and exploration.
AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.