Riphean low-carbonaceous shales of the South Urals in the context of formation of large igneous provinces

Abstract

Relationship of large magmatic/plume events, warm periods, and epochs of accumulation of variably С_org–rich sediments is considered by the example of Riphean low-carbonaceous shales of the western slope of the South Urals. It is shown that this relationship presumably exists for some of the indicated events (as for Early Precambrian superplume events), and does not exist for others. The formation of organic carbon-rich sediments in the Late Precambrian was likely controlled by other external and internal factors than in the Early Precambrian, relationships between which are so far poorly understood. It is also possible that the lesser scale of plume events in the Late Precambrian as compared to previous epochs could lead to the obliteration of their influence on the formation of С_org–rich sedimentary rocks, as well as to the local accumulation of the latters.