Some features of the sebesis of the Balka shyroka deposit (Ukrainian shield) according to the thermobarogeochemical research results

Abstract

The processes of mineralogenesis at the Balka Shyroka deposit (Middle Dnieper region), sequence and thermobaric conditions of formation of stable paragenesises, mineral associations and complexes are characterized. It is proved that a sub-isochoric trend of ore-genesis development was revealed at the deposit. The deposit is medium-pressure (up to 200 MPa), high-medium-temperature, belongs to the deposits of great depths (according to N. Petrovska, 1973) relative to the syn-ore paleosurface. The processes of remobilization and redistribution of ore components are clearly revealed: there was a regrouping of gold, initially localized in hemogenic ferruginous quartzites, while gold also was “borrowed” from basic-ultrabasic associations of deep areas. Jaspilites, as the source of this gold, simultaneously acted as lithological and geochemical barriers-precipitators of this metal. All this (combined with the fact that the ore bodies often overreach the strata of jaspilites) indicates the epigenetic nature of gold mineralization relative to the jaspilite strata. The most important aspect of the applied implementation of thermobarogeochemical criteria for any deposit that will be explored and evaluated from a geological-economic point of view is the analysis of the probability of spreading gold-bearing ore zones and ore bodies with depth. This analysis is based on data on the average value of thermobarogeochemical gradients and is generally reduced to extrapolation of the patterns of their change vertically and on the flanks of ore-bearing structures. Thus, it is possible to predict not so much the behaviour of mineralization, but the spatial boundaries (depth) of physicochemical factors of ore concentration, favourable for the formation of mineralization. On this basis, the productivity of ore bodies in the “O” profile with depth has been evaluated and favourable thermobarogeochemical criteria for gold mineralization are proposed.