Nature of Carbonaceous Rocks in Shear Zones in the Dal'negorsk District, Primorye: Black Shales or Mantle-Related Ilmenite-Graphite Metasomatites?

摘要

Data reported in this paper suggest that a significant part of rocks in the tectonite zone of the Dal'negorsk borosilicate deposit represents carbonaceous rocks of sedimentary framing. These rocks are probably confined to sectors involved in the crushing and dislocation of Mesozoic units of the folded basement of the region (carbonaceous siliceous and clayey siltstones and mud-stones associated with jaspers and cherts). The latter rocks were subjected to diagenesis, tectonic stress, crushing, thermal metamorphism, and superimposed mineralization. The carbonaceous rocks are marked by the preferential precipitation of sulfides of Cu, Zn, Pb, and other metals. Therefore, such rocks can serve as a prospecting guide for hydrothermal mineralization nodes.Elaboration of criteria for the differentiation of mantle-related carbonaceous metasomatites and metalliferous black shales is an urgent issue that remains to be solved.