3.51 Ga old felsic volcanic rocks and carbonaceous cherts from the Gorumahisani Greenstone Belt – Insights into the Palaeoarchaean record of the Singhbhum Craton, India

Abstract

In the Singhbhum Craton of India, Palaeoarchaean greenstone sequences have so far been reported from the south of the craton. In this study, we report a precise 3510 ± 3 Ma U-Pb LA-ICP-MS zircon age from a well-preserved felsic volcaniclastic unit of the Gorumahisani Greenstone Belt (GGB) exposed in the north-eastern part of the craton. The volcano-sedimentary sequence of the GGB comprises a typical Palaeoarchaean greenstone succession of submarine ultramafic to felsic volcanic rocks intercalated with banded iron formation and abundant carbonaceous chert. Chert of the GGB comprises banded black-and-white chert, granular chert, laminated chert and massive black chert, in striking similarity to Palaeoarchaean greenstone successions in South Africa and Australia. Raman spectroscopy of carbonaceous matter yielded an average of ~460 °C as an estimate for the peak metamorphic temperature in the study area. The good preservation and only greenschist-facies metamorphic conditions make the GGB an interesting target for Early Earth studies.