Synchronism of the Paleoproterozoic development of the phenomenon of “Shunga” in analogues basins

Abstract

The sequence of interrelated events – from accumulation to secondary concentration and dispersion of organic matter characterizes the unique phenomenon of “Shunga” for Paleoproterozoic, most fully investigated in the Onega sedimentary basin. The main stage is the accumulation of huge volumes of primary organic matter, as well as the subsequent stages of its redistribution of numerous domed and subplastic local bodies of high-carbon rocks with characteristic differentiation of composition; various forms of anthraxolite manifestation, indicating the implemented full-scale process of hydrocarbon generation, numerous types of collectors, indicating their migration; traces of decomposition of both primary and newly formed organic matter. In the review, on the example of the Franceville basin, the evidence of the existence of all stages of the phenomenon in analogs, in which the main stage developed synchronously, is presented. The results of dating deposits of the two basins are analyzed in detail, fundamental errors in the interpretation of geochronological data are revealed. It is shown that the correlation of Paleoproterozoic sedimentary basin sections is possible by geochemical marking horizons with δ13Corg anomalies and high content of U, Mo, Se, As, Ni, V.