GEOCHEMICAL FEATURES OF SILICY AND SILICY-CARBONATE METASOMATITES IN CRETACEOUS AND PALEOGENE DEPOSITS IN LOWER VOLGA REGION

Abstract

The chemical composition and microstructure of Paleocene quartzite sandstones and Upper Cretaceous siliceous-carbonate rocks in the Volgograd right bank of the Volga River have been studied. Numerous pipe-like channels, along which hot silica-saturated solutions flowed at the stage of sand cementation are found to have a two-layer structure. The inner layer consisting of dense quartzite has been enriched with ore elements (Fe, V, Cr, Mo, Ni, W, and Cu). Majority of detected ore phases is presented with reduced forms while minority is represented with sulfide and oxide ones. Siliceous-carbonate rocks contain high concentrations of strontium, chromium, molybdenum, tungsten, and uranium in addition to calcium in cold carbon dioxide solutions outputs.