The Vihanti-Pyhäsalmi district is located at the border zone between the Archaean craton in the northeast and the Palaeoproterozoic Svecofennian domain in central Finland. It is part of the Savo belt and contains one operating and four past mines and several uneconomic VHMS (Volcanic Hosted Massive Sulphide) deposits. Regional, semi-regional and mine scale 3D models of the Vihanti-Pyhäsalmi area were built in order to understand the formation of the VHMS deposit and accordingly map the ore critical geological formations and structures. In addition to the 3D modelling of the present day geology, structural geological inference was used to build 3D geological models visualizing the main deformational stages in past. The used data and information consisted of geological maps and reports, drill core logs, lithogeochemistry, reflection seismic profiles, potential field measurements and electromagnetic surveys. The geophysical 2D and 3D inversion were used to assist the 3D geological modelling seeking for continuity of the surficial structures especially in areas with only few or no drill core data. As a result, regional and semi-regional 3D models of the Vihanti-Pyhäsalmi area were obtained and new zones with VHMS exploration potential were identified in the vicinity of the Pyhäsalmi mine.
1988: Early Proterozoic stratigraphy of the Salahmi-Pyhäntä area, central Finland, with an emphasis on applying the principles of lithodemic stratigraphy to a complexly deformed and metamorphosed bedrock. Bull. Geo!. Soc. Finland 60, Part 2, 79-106.The medium-highly metamorphozed and intensely deformed early Proterozoic supracrustal rocks of the study area, located at the boundary zone between the Karelian and Svecofennian zones in central Finland, are classified following the recommendations of the North American Stratigraphic Code into 16 lithostratigraphic and lithodemic units.The lithostratigraphic procedures can be applied only to the southeastern corner of the area where the late Archaean basement complex is rimmed by less than 100 metres thin fluvial metapsammite formations locally underlain by a thin palaeosol of sericite and chloritoid schists. These formations, which are correlated with the Kainuu tectofacies, are overlain by at least 1 km thick sequence of turbiditic metapsephites and metapsammites of the Haajainen and Rotimojoki formations of the western Kaleva tectofacies.The major central part of the area is cored by two gneiss complexes, earlier considered to be the Archaean basement, but now classified mostly as lithodemic derivatives of the Kaleva tectofacies. These complexes are mantled by gneisses and schists which represent western, more metamorphosed distal equivalents of the Haajainen and Rotimojoki formations. The western margin of the area is composed of gneisses and schists part of which show Svecofennian affinities.Excluding the Archaean basement, the area is intruded and migmatized by Svecokarelidic intrusive rocks.
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