Prospect of studying Bijaigarh Black Shale, Vindhyan Supergroup, and its implication for Mesoproterzoic oxygenation

Abstract

This paper reviews the studies of Bijaigarh Shale in the wake of improved trace element and sulphur isotope tools as a potential avenue for the hitherto unknown oxygen fluctuations during Mesoproterozoic Era. Black shale is traditionally known as an indicator for the anaerobic environment. However, the source for high organic remains in the black shales suggests a high primary production pathway which is most likely oxygen-producing photosynthesis. That means atmospheric carbon would have been sequestered in aerobic condition. Mesoproterozoic Era (1600-1000Ma) also
has many black shale strata, and it is traditionally accepted that the Mesoproterozoic ocean was sulphidic and anaerobic in nature which retarded the biological evolution for a long time and delayed augmentation of metazoa. However, with improved understanding of trace elements and sulphur isotope analysis very recently Mukherjee and Large (2016) demonstrated a fluctuation in oxygen condition during Mesoproterozoic Era.