Archaean greenstone belts of the Singhbhum Craton, India–windows into early Earth

Archaean greenstone belts offer the opportunity to study the dynamic conditions on early Earth. The Singhbhum Craton of India hosts several volcano-sedimentary greenstone sequences that preserve Archaean rocks locally exceeding 3.5 Ga. We present a compilation of field, petrographic, geochemical, and geochronological results from the following greenstone sequences: 1) Daitari Greenstone Belt, 2) Gorumahisani Greenstone Belt, and 3) Nausahi Greenstone Belt. Major similarities include the association of mafic-ultramafic sequences, felsic volcanic rocks, and sedimentary units. These greenstone belts host altered carbonated/silicified volcanic rocks and cherts; an assemblage typical for Palaeoarchaean successions. The cherts include bedded orthochemical sediments, silicified shales, silicified volcaniclastic rocks, and hydrothermally derived vein cherts. In all greenstone belts, the cherts preserve carbonaceous matter, which provides evidence for microbial life as old as c. 3.5 Ga ago. Raman thermometry of carbonaceous matter indicates greenschist facies grade of metamorphism. The Daitari and Gorumahisani belts host economic ore deposits (e.g., iron and minor gold respectively). In contrast, despite their akin lithological assemblages the Nausahi belt is yet to be prospected for such economic deposits. Therefore, understanding the geologic evolution of these greenstone belts will be crucial to evaluate early Earth processes and related mineralization from the Archaean record of the Singhbhum Craton.