ORE-BEARING POTENTIAL OF IMPACT RING STRUCTURES

The present article is based on data obtained by the study of the Puch ezh-Katun and Popigai impact ring structures (astroblemes). The struct ures were found to be diamond-bearing; therefore, they were prospected and explored. As a result, a complex multistage development of the ri ng structures and their endogenous nature were revealed. The formation of ring structures starts with deep-seated high-power fluid explosion s leading to the development of platformal basement uplifts. This proc ess is accompanied by deep subsidence of the surrounding blocks and fo rmation of peripheral calderas. Approaching the surface, the deep-seat ed fluid explosions affect granite-gneiss uplifts and form explosive c raters in their central sectors. The explosive waves disintegrate and partially melt the granite-gneiss mass, which is partly precipitated b ack into the ring structures. Here, this material fills the bottoms of the central explosive craters and peripheral subsidence calderas to f orm allogenic breccias. The diamond-bearing potential of the impact me lts is derived at the expense of graphite of the initial gneisses and the development of the reactions H-2 + CO = C (diamond) + H2O. This pr ocess accompanies a unique impact melting of granite-gneisses differen tiated with respect to several minerals. The produced silicate melts d iffer from the initial granite-gneisses by high contents of many ore m etals: it testifies to the ore-bearing nature of the fluid flows origi nating in these explosive structures. Approaching the surface, the flu id flows, having an initially hydrogen composition, experience transfo rmation and become saturated with water, decreasing the temperature of fluid melting of the crust and mantle. As a result, the formation of explosive chambers below the ring structures is accompanied by the man ifestation of ore-bearing magmatism, metasomatism, and stratiform ore mineralization. During the ascension of ore metals, transport reaction s change the migration forms of these metals, for example, H-2 + CO 3AuCl = C + 2Au + H-2 [AuCl3O]. These reactions reflect a joint accumu lation of ore metals and carbon, typical for stratiform deposits relat ed to ring structures and black-shale type ore deposits.