RAJALAMPI GOLD-RARE METAL OCCURRENCE IN THE HAUTAVAARA STRUCTURE, KARELIA: LOCALIZATION PATTERN, MINERALOGICAL AND GEOCHEMICAL INDICATORS
DOI: 10.24411/0869-5997-2018-10012
Keywords:
Au-Bi, Au-S-As mineralization, Rajalampi ore occurrence, metasomatic alterations, gabbro, greenstone structure, Karelia.Abstract
The authors report the results of the integrated geological study of magmatism, near-ore metasomatic rocks and ore composition of the Rajalampi gold-rare metal occurrence, new to the region, in the Hautavaara structure, Southern Karelia. Metasomatic alterations of gabbro and host rocks in a NNW-trending shear-zone were accompanied by the formation of
Au-Bi mineralization located in common zoning with Au-bearing sulphoarsenide. The ore zoning revealed reflects the stepwise pattern of a hydrothermal process and the pulsed pattern of the supply of oreforming solutions. The poor sulphide dissemination of the external zone (1–6%) is replaced by sulphoarsenides (1–6%) of the intermediate zone and then by the gold-bismuth mineralization (1–2%) of the central part of the ore zone. In the arsenopyrite mineralization zone As concentration increases to 5,3, Pb 0,28, Cu 0,12%, Au 1,92, W 34,5 and Bi 7,4 g/t. In the central part of the ore zone productivestage mineralization is represented by native highgrade gold associated with native bismuth and highbismuth minerals. Au concentration is 7,8–283 g/t, Bi – 0,8%.
