GEOLOGY, MINERALOGY AND SOIL SCIENCE

. The main results of the study of the nature of secondary (after sedimentation) processes in the Lower Carboniferous carbonate-black shale formation of the southwestern part of the Folded Donbass, located in the zone of influence of the Volnovakha deep fault, are presented. Mineral indicators of fluid-geodynamic (hydrothermal) processes and manifestations of bitumen in carbonate-black shales of the Lower Carboniferous age were studied.

Introduction.The study of secondary (post-sedimentation) processes (PP) in formations of different composition is always relevant, especially for oil and gas rock-reservoirs.PP is the result of the activation of geodynamic and geothermodynamic processes in sedimentary rock basins, which lead to a variety of manifestations of secondary transformations [1].PP are especially intense in rock of the basins in fault zones where post-volcanic activation occurs with the removal of hydrotherms and various exhalations.Figure 1 shows examples of PP manifestations in rocks of various compositions: cavernousness, porosity and lithogenetic cracks in a dolomite-limestone block (Donbass) (Fig. 1, A), leaching in pyrite (Donbass) (Fig. 1, B), formation of quartz globule in a jasper rock geode (Zavalye quarry, Ukraine) (Fig. 1, C).No 179

Examples of the manifestation of secondary processes in various rocks
Research results.We have studied in detail the rock and mineral composition of the Lower Carboniferous carbonateblack shale formation of the Folded Donbass.
Field studies were carried out in four quarries of the Dokuchaevsky district (Central, East Dolomite, Dolomite, Stylsky), located in the Volnovakha structural-tectonic zone in the southwestern part of the Folded Donbass (Fig. 2).These quarries record geodynamic manifestations such as faulting and folding, active post-magmatic processes (dikeeffusive, hydrothermal), clayey diapirism, carbon metasomatosis and submarine paleovolcanism (Fig. 3, A,B,C,D).The Lower Carboniferous carbonate-black shale formation of the southwestern zone of the Folded Donbas is about 600 m thick and occurs at depths of up to 1 km (perhaps 1-2 km) and is exposed in deep (>100 m) quarries.
Carbonate and black shale rocks were significantly affected by post-magmatic hydrothermal processes (leaching, solution, carbon metasomatosis), which carried liquid-gas fluids, thermal energy, and a wide range of ore and biologically active elements.The material reflection of hydrothermal processes is the large growths of stalactitelike pyrite and pyrite-marcasites of tube-like appearance with empty channels, which were 30 and 65 cm long and 20 and 60 cm in diameter (Fig. 4, d, e, g Hydrothermal processes are also indicated by thick veins (up to 5 meters wide) of white calcite with bituminous inclusions, thin veinlets of anthraxolites, lenses of fluorites with gas-liquid inclusions (Fig. 4,a,b,c), accumulation of bitumens of hydrothermal origin in porous carbonates (limestones and dolomites) (Fig. 5 ).Veins of calcite fluidisites can serve as an additional exploratory indicator for identifying areas of permeability in rocks.These minerals in the rock complexes of the southwestern Donbass reflect the multi-stage processes of ore and mineral formation that occurred in the temperature range (30-500C to 2800C and above) and pressure (120-800 atm).In addition, in the development zone of the formation under study, almandine-pyropes and xenocrystals of chrome spinels were found [6], indicating the deep origin of magmas and the presence of mantle faults.The latter served as pathways for the migration of post-magmatic hydrothermal solutions from high-temperature magmatic to low-temperature post-magmatic, which led to a variety of secondary mineralization and ore manifestations.
Conclusion.The carbon carbonate-black shale formation of the southwestern part of Donbass has been studied in terms of the development in it of mineral indicators of superimposed (secondary) processes, which are indicators of tectonogeodynamic processes in the earth's crust.The presence of anthraxolites, vein bitumens, carbon matter and methane through inclusions in calcite and quartz, accumulations of viscous bitumen in cavernous limestones make it possible to

Figure 2 Fragment
Figure 2 Fragment of the geological map of the southwestern part of the Folded.Donbas.Outcrops of Lower Carboniferous carbonate-black shale strata are indicated by an asterisk.1 -the boundary of the suite in the terrigenous Carboniferous stratum. 2 -carbonate stratum of the Visean stage.3 -is the same for the Tournaisian age. 4 -polymict sandstones and gravelites of the Upper Devonian.5 -basalts and tuffs of the main rocks of the Upper Devonian.6 -Middle Devonian sandstones.7 -Paleozoic andesites and monzonites.8 ̶ Precambrian crystalline rocks.9 -tectonic disturbances.10 -research areas of carbonaceous terrigenous-carbonate deposits, blocks: I ̶ Novotroitskyi, II ̶ Stilskyi.11 -exposure of black shale deposits

3 A
This work is distributed under the terms of the Creative Commons Attribution-ShareAlike 4.0 International License (https://creativecommons.org/licenses/by-sa/4.0/).Proceedings of the 8th International Scientific and Practical Conference «Current Issues and Prospects for the Development of Scientific Research» (November 19-20, 2023).− central deep quarry, B − folding of carbonate-black shale formation, C − penetration of a vertical dike into carbonate-black shale rocks of Tournaisian age, D − thermal impact on black shale source rocks (Donbass) ) [2, 3].Pyrites of this This work is distributed under the terms of the Creative Commons Attribution-ShareAlike 4.0 International License (https://creativecommons.org/licenses/by-sa/4.0/).Proceedings of the 8th International Scientific and Practical Conference «Current Issues and Prospects for the Development of Scientific Research» (November 19-20, 2023).Orléans, France No 179 morphological type in the Stilsky quarry are confined to the tectonic voids in the black dolomitized limestones (enriched in organic matter) at the boundary of the Upper Devonian and Lower Tournaisian.This indicates the development of a hydrothermal field formed in the zone of an ascending relatively high-temperature fluid flow under the conditions of the Stilsky horst.According to [4], the temperature of mineral formation for pyrites in zone of articulation of the Folded Donbas with the Azov crystalline massif is 330-2600C.

Figure 5
Figure 5 Bituminous substance from cavernous Tournaisian limestones of the bioherm type