Nanodispersed state of metals and their migration in carbonaceous natural media

Abstract

Carbonaceous (black) shales containing increased metallogenic potential [1, 2] are generated in definite geodynamic and paleogeographic conditions: predominantly in stagnant riftogenic sea basins where the sedimentary process is accompanied by a supply of products of volcanic and underwater hydrothermal activity [3]. The carbonaceous sedimentary and volcanogenic‐ sedimentary formations generated in such conditions possess all the necessary ore-genetic potentials (fluid‐ metallogenic and barrier‐geochemical). Metals are therewith often dispersed in the carbonaceous‐mineral rock groundmass and do not form separate mineral macroscopic phases. At definite stages of the postsedimentation transformation of carbon-containing sediments (diagenesis, katagenesis), biopolymers and geopolymers are generated in it. Under the increasing PT-conditions in the interior, these substances become a source of liquid and gaseous (and able to migrate) components of oils, and all at once to a significant degree inherit the metallogenic potential of the oil source carbonaceous rocks. This is confirmed by the discovery of deposits of oils and bitumoids enriched in metals in different regions of the world [4, 5]. Now there is significant evidence that the processes of oil and ore formation in black shale strata are closely connected [3, 4]. However, questions such as the types of bonds of metals with carbonaceous matter, ways of metals migration in carbonaceous media, and conditions of their concentration at different physico-chemical barriers with formation of ore deposits remain practically unsolved.