Mineralogical and geochemical features of the black shales surrounding the Kara Astrobleme (Pay-Khoy)

Abstract

Research subject. The Late Paleozoic (D3–P1) black shale strata surrounding the Kara Astrobleme (Pay-Khoy) were studied. Materials and methods. The rocks were sampled radially along the profile from the edge of the astrobleme (the at the contact zone with impactites) with access to black shales that were not affected by post-impact transformations. An analysis of the mineralogical and geochemical features of the black shales surrounding the Kara astrobleme was carried out using a complex of modern research methods (Geonauka Centre for Collective Use, IG FRC Komi Scientific Centre, Ural Branch of the Russian Academy of Sciences) in order to identify the possible mobilisation, re-deposition and concentration of ore matter under the conditions of intensive post-impact hydrothermal altering. Results and conclusions. The geochemical features of the black shale deposits altered by post-impact hydrothermal processes in the vicinity of the Kara impact structure were determined. The sharp abnormal contents of Mn, B, Zr, Sr, Ge, Cd, Hf, Se and Eu as well as the abnormal contents of Ti, Ba, Cr, Rb, Li, Ce, La, Ga, Sc, Co, Cs, Gd, Dy and W were revealed. The geochemical concentration specificity of components in different regions of the Kara astrobleme associated with the specialisation of target rocks was established. Raremetal and rare-earth minerals, sulphides and thymannite (HgSe) were diagnosed.

Keywords

• black shales
• rare-earth minerals
• metal mineralisation
• hydrothermal processes
• post-impact transformations
• ore-bearing potential
• kara astrobleme
• pay-khoy