Geological and geophysical features of the polygenicpolychronous nature of the gold ore manifestations of Donetsk aulacogen

Abstract

The results of a metallogenic analysis of new data obtained during geological exploration and regional geophysical work in the Donets basin, which is the central fragment of the Dnieper-Donetsk riftogenic system, are presented. According to the results of metallogenic analysis and mathematical processing of geophysical data, including the original technology of object-oriented filtering, the polychronism and polygenicity of gold mineralization is established, corresponding to the poly-phased development of Donetsk aulacogen. In the composition of gold ores, two main types are distinguished: 1) large-volume zones and stratiform deposits of gold-sulfide-vein-disseminated mineralization in sandy-shale carbon strata, belonging to sedimentary (metamorphic) -hydrothermal genetic class, associated with lithogenesis and metamorphism of stony-carbon metamorphism at the preorogenic stage of development of aulacogen (Bobrikovskoye and other deposits); 2) epithermal quartz veins and local vein-vein zones of gold-silver-polymetallic mineralization associated with the development of central-type volcanic-plutonic apparatuses at the stage of Mesozoic tectonic-magmatic activation of aulacogen, identified according to geophysical data (Kerchik and other ore occurrences). The assignment to the sedimentary (metamorphogenic)-hydrothermal genetic class of Bobrikovsky type gold-bearing mineralizations is justified by the features of localization, distribution and material composition of the ores, as well as the peculiarities of the geological structure of the Donbass, characteristic of classical ore regions with a similar type of mineralization in carbon-terrigenous (black shale) formations the position of folded structures and the absence of granitoid magmatism, a pronounced asymmetry of folded-discontinuous structures, with the carbon-terrigenous and carbonate formations of varying degrees of their post-sedimentation transformation, the presence of stratified sulfide mineralization. The isolation of the Mesozoic volcanic-plutonic structures of the central type, which are associated with the zythermal gold-bearing mineralization of the Kerchik type, is based on the detection of isometric positive anomalies of the magnetic field, coupled with isometric negative anomalies of the gravitational field, as well as the outputs of igneous rocks. Gold-bearing ores of the Bobrikov type identified in the Western Donbass to date are objects of early pre -ogenic mineralization of a gold-sulfide-vein-disseminated type in carbon-terrigenous complexes. The gold-silver-polymetallic ores of the Kerchik type discovered in the East Donbass to date represent a late-productive stage associated with the regeneration and redistribution of pre -ogenic gold-bearing mineralizations at the stage of Mesozoic tectonic-magmatic activation.