Geophysical surveying in the Petchenga and Lotta area, Kola peninsula, USSR.

Abstract

As a part of the cooperation between the Geological Institute, Kola Scientific Center of the USSR Academy of Science and the Geological Survey of Norway, seismic and slingram profiling was carried out iin 6 areas on the Kola peninsula. Aims of these investigations; 1) mapping of soil thicknesses and composition, 2) locating conductive structures in bedrock, 3) studies of P-wave velocity anisotropy. Interpretation of seismic velocities indicates three layers in the overburden; 1) loosely packed sand, P-wave velocity: 300-700 m\/s, 2) loosely packed till, P-wave velocity: 1000-1500 m\/s, 3) compact till, P-wave velocity: 1900-2200 m\/s. The overburden thickness is in the range 0-30 meters. Slingram measurements have delineated conductive zones in more detail than previous electrical profiling (MISC). Electrical measurements are more sensitive to structures with low conductivity than slingram measurements. A correlation between high conductivity and low P-wave velocity in bedrock is indicated. This is probably due to fracturing. There is an indication of slightly higher P-wave velocity along the bedrock strike direction than across (anisotropy).