Ishchenko L. Geochemical characteristic of the ore waters of bitumen-hydrothermal mineral associations in rocks of the West-Donetsk graben

The goal of the work is to study the geochemical features of the ore waters of bitumen-hydrothermal associations in the rocks of hydrothermal mercury and mercury-polymetallic ore fields of the West-Donetsk graben of the Dnipro-Donets rift. The factors and processes of forming the chemical composition of groundwater are investigated. Within the areas with hydrodynamic faults there is a hydrogeochemical inversion, resulting in sodium chloride waters having very low or very high mineralization in the waters of the regional background. This indicated to the modern processes of heat and mass transportation in zones of anticlinal structures. The isotopic composition of the carbon of the bitumens of the hydrothermal ore fields of the Donetsk Basin is established. The content of the heavy isotope 13С in the bitumen of the Nikitovsky, Druzhkovsko-Konstantinovsky and Slavic ore fields is determined by the values of 13С in the range -18.27 ÷ -27.0 ‰ (PDB standard). This indicates that the predominant source of their formation were the carbonaceous rocks of the middle and upper Carboniferous, but there is in samples is heavy isotope of carbon, which are indicating in the mineral formation of deep fluids. The genetic model of formation of bitumen-hydrothermal associations of ore fields of the region was constructed by the interaction of inorganic (contact metamorphism) hydrocarbons and organic substance of carbon layers. The geochemical features of dissolution of sulfide minerals by underground waters in the zone of free water exchange (zone of hypergeenesis) are analyzed. Such processes are possible in sodium chloride and sulfate (chloride) sodium groundwaters in acidic or alkaline pH environment. However, such natural conditions are not capable of providing sufficient amounts of sulfides to form the ore waters around ore solids, within are indicating the presence of a deep source of ore-bearing components. Synergetics fluidodynamics model of formation of ore waters of bitumen-hydrothermal mineral associations was constructed with participation the dissolution of sulfide minerals in the zone of supergene and ascending unloading to faults of deep waters with hypogene mineral-forming ore elements. The method of geochemical search of hidden hydrothermal mineralization and oil and gas accumulations has been improved. The use of features of the formation of the chemical composition of ore waters is considered for the explanation of the processes of formation of bitumen-hydrothermal mineral associations and ore waters to use for prediction of oil and gas fields.