Application of multiple data sets to structural studies on Varanger Peninsula, Northern Norway†

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Abstract
A synergistic approach has been used to define the lineament framework of the Varanger Peninsula, in particular the Trollfjord-Komagelv Fault Zone, in northern Norway. This included the integration of remote sensing, geophysical data sets, digital elevation data and geological field observations. Digital image processing techniques have been applied to the satellite images, raster aeromagnetic and gravity, and digital elevation data. The Trollfjord-Komagelv Fault Zone divides the Varanger Peninsula into two structurally distinct regions, one dominated by an allochthonous basin to the north, and an autochthonous/parautochthonous basin to the south; both contain metasedimentary rocks of Late Precambrian to Early Cambrian age. The fault zone is a major regional strike-slip fault zone which can be traced to the northwest into offshore basins in the southwestern Barents Sea; and to the south-east along the northern coast of the Kola Peninsula. This study has shown that the Trollfjord-Komagelv Fault Zone is probably part of a regional NW-SE to WNW-ESE lineament system which is well defined in the Archaean to Protero-zoic crystalline rocks to the south of the Varanger Peninsula. Gravity gradients and magnetic anomalies associated with these lineaments indicate that they are deep-seated fractures; and in most places they are expressed as topographic lineaments. The kinematic analyses of conjugate shear fractures and fault-slip data suggest that the region has experienced multiple horizontal/subhorizontal com-pressional stress fields with different orientations, the NW-SE and NE-SW being most significant, in time and space. Preliminary observations also suggest a shift of the el from horizontal/subhorizontal to vertical/sub vertical with time. The occurrences of these multiple tectonic events indicate that the lineaments are composite shear zones and tensional fractures which were probably affected by repeated movements of varying sense in response to variations in the regional stress fields.