Features of carbonaceous rocks surrounding the Kara astrobleme: statistical analysis of geochemical data

Abstract

Introduction: The Kara astrobleme is specific by the composition of the target rocks, represented by carbonaceous shales and siltstones, primarily enriched with useful components. Large astroblemes reveal intensive hydrothermal processing of host rocks, which can stimulate the mobilization, redeposition and concentration of ore matter. In this regard, to establish a possible post-impact hydrothermal effect on the target rocks, including with the participation of asteroid matter, we analyzed the geochemical composition of carbon-containing rocks of the surrounding of the Kara astrobleme using multidimensional statistics. Methodology: We conducted the analysis of the material composition of carbonaceous rocks of the Kara astrobleme surrounding by methods of multidimensional statistics – correlation, factorial and hierarchical cluster methods. Results and discussion: In the carbonaceous rocks of the Kara astrobleme surrounding, a strong relationship between the elements Cu, Zn, Sr, Y, HREE and U has been established by mathematical statistics, which indicates a genetic relationship between ore and rare earth minerals. Ni, Co, Zn and Cr are strongly correlated with each other and are concentrated in ore minerals. The elements Mo, Tl and V are genetically connected with aquagenic organic matter. The factor analysis data indicate the introduction of rare components (Cs, Rb, Th, Nb, Ta, Sn, Be, Sc and Pb) resulted with hydrothermal activity. We have established that the carbonaceous rocks of the target around the zone of the suevites distribution are characterized by higher contents of Ni, Co and Cr, relative to the rocks of the initial substrate set far from the rim of the astrobleme. Conclusion: As a result, we revealed the geochemical specificity of the components, generally indicating the contamination of the target rocks of the Kara astrobleme by some ore and rare earth elements by the post-impact hydrothermal activity, mobilization, redeposition and concentration of the substance. The analysis of the contents of Ni, Cr and Co indicates partial enrichment of the target rocks by cosmic matter in the area of intense impact crushing, disintegration and hydrothermal mineralization.