Известия Томского политехнического университета: Инжиниринг георесурсов (Jun 2018)
Typification of platinim metal bearing picrites from the north-west of Kansk greenstone belt (East Sayan)
Abstract
The objects of the study are mafic-ultramafic complexes of Kulibinsk potential ore unit, including intrusive bodies of kingashsk complex and metavolcanic rocks of kuliginskaya and kuzinskaya series; the studied objects are located at the north-west edge of Kansk green-stone belt in East Sayan. The aim of the research is to study petrographic, petrochemical and structural characteristics of the studied objects, their typing and development criteria for selecting ore-potential areas. Methods. Petrographic study of the rocks was carried out on the polarization microscope AxioScop 40 firm Carl Zeiss. Investigation of the gross composition of the rocks was carried out at the Vinogradov Institute of Geochemistry SB RAS (Irkutsk) and in the laboratory of Minusinsk Geological Prospecting Expedition. The concentration of rare-earth elements was determined by ICP-MS, which was held in the Analytic Center of Natural Systems Geochemistry of National Research Tomsk State University (Tomsk) and at the Vinogradov In+ stitute of Geochemistry SB RAS (Irkutsk). Results. According to the set of petro-geochemical criteria the authors have identified five types of mafic-ultramafic metavoulcanic rocks, four of them are represented by the rocks of basalt-melapicritic formation, which associates with intrusive massifs of kingashsk complex. Fifth type of metavolcanites is similar to the calcalcalic basalts and it can be determined macroscopic among other formations. The rocks of basalt-melapicritic formation together with intrusions of kingashsk complex form volcano-plutonic complex, that is productive for platinum group elements, Cu, Ni; these formations are products of differentiation of the same high-mg melt. The studies identify the criteria of distinction of metabasalts on two types, one of them is included in ore-bearing volcano-plutonic association, and the other one is widely distributed only at non-ore parts of the studied territory.
