STRUCTURAL CHARACTERISTICS OF THE KALLIVOLAMPI FLUORITE-SULPHIDE OCCURRENCE, VEDLOZERO-SEGOZERO GREENSTONE BELT, KARELIA
The exposed zone of the Kallivolampi fluorite-sulphide occurrence, located at the tectonic contact of heterogeneous Lopian (Neoarchean) and Sariolian (Paleoproterozoic) rocks, clearly displays structural differences in shears of various ages. The numerous parageneses of subplanar structural elements (PSSE) were detected and identified using tectonophysical methods. Their comparison indicates that they formed in post-Sariolian time. The multi-phase pattern of the shear and signs of a multiple activation of most of the structural elements were revealed. The most probable deformation regimes of SPSE formation were recognized: a dominantly faulting and wrench fault regime in an early, pre-ore stage and a dominantly shear and wrench-fault regime in a late ore and probably post-ore stage. Considering the presence of noble-metal minerals among the ore minerals, this ore occurrence can be compared with gold bodies. Many PSSEs in the zones of the Kallivolampi ore occurrence and the Post-Jatulian Pedrolampi gold deposit studied earlier, spaced far apart, were shown to be fairly similar and even fully identical and to have formed in the same deformation regimes. The general formation sequence of shears differing in spatial orientation was as follows: structures with the predominant north-western and north-north-western strike of displacement planes were the first to form; these were followed by structures with the dominantly north-north-eastern strike of general displacement planes. The similarity, evolution sequence, and deformation conditions of the structures suggest that they were produced by one Paleoproterozoic, Post-Jatulian ore-generating system. Further tectonophysical and geochronological studies are needed to find out whether other gold bodies with varying characteristics revealed in the Vedlozero-Segozero greenstone belt and its flanks belong to this system.