Deformation and recrystallization of sulfide interlayers at the Golets Vysochaishii Gold-Ore Black-Shale Deposit

Abstract

Research subject. The relationship of sulfide interlayers in silt-pelitic rocks with the cleavage of the axial surface at the Golets Vysochaishii gold-ore black-shale deposit (Bodaibo ore district). Methods. The structure of rocks was studied in out-crops, borehole cores, sanded samples, transparent and polished sections. The chemical composition of minerals was determined. Results. It was established that sulfide and sulfide-containing interlayers undergo deformation and recrystallization together with the host silt-pelitic rocks during plastic dynamometamorphic transformations of rocks. Conclusions. Metamorphic transformations of rocks took place in two stages. During the folding-thrust deformations of the first stage, a cleavage of rocks is formed, which leads to the splintering of sulfide interlayers with the orientation of the lenses along the cleavage. Metamorphic transformations of the second stage are manifested in sulfide and sulfide-containing interlayers in the collective recrystallization of their composing minerals with the replacement of surrounding rocks deformed at the previous stage. The second stage is characterized by changes in the mineral composition of rocks, manifested in the substitution of pyrrhotite with pyrite, increase in the iron content of chlorites and carbonates.