Ground-penetrating radar profiling in the Pasvik and Pechenga areas

Abstract

As a part of a cooperation program between the Geological Survey of Norway (NGU) and the Russian Academy of Science, ground-penetrating radar (GPR) measurements have been performed in Pasvik and along the Rayakoski and Shuoni- Kuets profiles in Russia. The aims of the investigations have been, 1)locating conductive structures in bedrock, 2) finding dip of conductive structures, 3) indicating zones of resistivity anisotropy, 4) mapping of overburden thick- nesses and composition and 5) delineation of structures in overburden and bedrock. A steeply dipping conductive zone at a test site along Shuoni-Kuets (profile 4200) showed resistivity anisotropy. A vague indication of resistivity ani- sotropy could also be seen in parts of the Pasvik profile. The bedrock reflector was difficult to recognize in areas with dry overburden, due to little or no contrast in relative dielectrisity between dry overburden and bedrock. The reflection configuration in the overburden was mostly hummocky or chaotic, indicating till. More fine-grained deposits (probably laminated fine sand\/silt) were indicated at some places by a parallel reflection configuration. Dipping or flat-lying reflectors in bedrock probably represent cracks or fractures.