Phanerozoic Endogenic Processes and Related Ore Genesis in the Voronezh Anteclise

The formation and tectonic reconstructions of the structure of the Voronezh Anteclise (VA) were accompanied by endogenic processes. Their influence resulted in the presence of volcanic rocks in sedimentary cover and related Ti placers, Cu, Pb, and Zn, intermetallides, ultrafine gold, and diamonds and their index minerals. Endogenic mineralization is typically developed in the Phanerozoic activation zones: linear areas, which are characterized by tectonic processes along the deep faults and a link with crustal and mantle sources. The rocks in these zones are fractured and become permeable for magmas, hydrotherms, and exhalations. Six epochs are distinguished as a result of these processes: 1, early Hercynian (Middle Devonian–Lower Carboniferous); 2, late Hercynian (Middle Carboniferous–Lower Triassic); 3, early Kimmeridgian (Middle Triassic–Lower Jurassic); 4, late Kimmeridgian (Middle Jurassic–Lower Cretaceous); 5, early Alpine (Late Cretaceous–Late Paleogene); and 6, late Alpine (Neogene–Quaternary). The Middle Devonian–Lower Carboniferous magmatism was characterized by several stages. The earliest alkali-basaltic stage in the Kaluga–Belsk structure in the north of the VA is dated by the Eifelian. The explosive Yastrebovsky stage in the southeast of the region corresponds to the Givetian–Frasnian boundary. Tholeiitic basalts (flows and vents), which formed several fields, erupted at the beginning of the Late Frasnian (Petinian) and, to a lesser extent, in its end (Evlanian–Livenian). The analogs of similar eruptions in the East European Platform are known in the Dnieper–Donetsk Basin and Timan. Volcanism is related to mantle sources, as well as the Proterozoic ultramafic rocks with Cu–Ni sulfides. They are overlain by exhalative late Hercynian Ni, Co, and Cu dispersion halos in sedimentary cover. The Early Carboniferous basal horizons contain index minerals of diamonds. Polymetallic mineralization in the Carboniferous terrigenous–carbonate rocks in the VA boundary areas and Dnieper–Donetsk Basin formed in the early Kimmeridgian epoch. The Upper Jurassic and Lower Cretaceous basal horizons contain small diamonds and their index minerals indicating the kimberlite (lamproite) magmatism. Its new outburst in the early Alpine epoch was characterized by hydrothermal processes during the formation of a granosyenite intrusion of the Shkurlatovo granite quarry. Fluids, which accompanied the ascending intrusion, formed ankerite metasomatite after corralite enriched in barite, oligonite, sphalerite, and other minerals. The late Alpine epoch was characterized by exhalative processes in sedimentary cover and the formation of ultrafine gold and intermetallides enriched in volatiles. The endogenic processes, which were overprinted on rocks of the sedimentary cover, led to the formation of a series of mineral deposits, the searching for and exploration of which may lead to the discovery of new deposits in the region. The Devonian magmatism resulted in volcanosedimentary Ti placers with an ilmenite content up to a few hundred kilograms per cubic meter and basalts for the production of the ballast crushed stone and stone casting. Basalts and ilmenite placers in the southeast of the VA occur in the overburden of Cu–Ni and graphite deposits and over granitic domes, opening possibilities for their complex exploitation. The overburden kaolinite, quartz sands, chalk, and brick loams increase the value of the deposits. The hydrothermal processes led to the formation of polymetallic ores in the southwest of the VA, where the chain of their occurrences is traced in deep fault zones. In the Cenozoic, the occurrences of ultrafine gold, one of which (Russkaya Zhuravka in the southeast) was found in last century, are related to exhalations in sedimentary cover. Because of the difficult metal extraction (7–12%), exploration works were stopped. The studies of diamond potential point to three epochs of kimberlite magmatism: late Hercynian, late Kimmeridgian, and early Alpine. The second epoch is the most reliable; thus, the kimberlites should first of all be sought below the Lower Cretaceous rocks.