Geochemistry of Paleoproterozoic cap-carbonate sequence from the Central India

What is it about?

Well-preserved sedimentological features of the Paleoproterozoic age Sausar Group of central India indicate glaciogenic origin for the diamictite in the lower part of the unit. Deglaciation was responsible for a marine transgression and the deposition of proximal glaciomarine facies and a cap-carbonate, followed by fine clastics with manganese ore. Analyses of d13C and d18O contents in the carbonate unit overlying the diamictite, together with Sr and Ba contents and REE data, indicate the preservation of primary geochemical signatures. The average d13Ccarb content ranges between −3.1‰ and +0.1‰ V-PDB, having peak negative d13C excursions of up to −7.4‰ V-PDB, similar to Paleoproterozoic and Neoproterozoic cap-carbonates elsewhere. High Sr and Ba contents indicate the presence of aragonite and barite precursors, similar to well-studied Neoproterozoic cap-carbonates. A single continuous carbonate unit shows d13C excursions from −4.4 to +2.6‰ V-PDB. The lithological association and chemostratigraphy are comparable with the carbonate-tillite association of the Huronian Supergroup of Canada, the Snowy Pass Supergroup of the USA, the Transvaal Supergroup of South Africa, and the Turee Creek Group of Australia.

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Why is it important?

A negative d13C excursion has been reported for the first time from India. Important for understanding the evolution of oxygen and Great Oxidation Event (GOE) during Paleoproterozoic.