Evolutionary history of Archean Greenstone Belts fringing Bonai Granitoid Complex, Singhbhum Craton, India and their stratigraphic correlation.

Singhbhum Craton (SC), one of the oldest continental crusts, has a nucleus of Singhbhum Granite Complex with volcano-sedimentary belts in peripheral parts. Deciphering the inter-relationship between volcano-sedimentary packages and surrounding granitoids offers considerable challenges. The present study area lies in the northwestern parts of SC. Lithounits of volcano-sedimentary packages drapes around the Paleoarchean Bonai Granite Complex (BGC). An attempt has been made to understand the basin development over BGC based on the mutual relationship between lithopackages of Iron Ore Group (IOG) and their structural disposition. It is proposed that two distinct basins, Koira and Gurundia, developed over BGC during Mesoarchean. While the Eastern Koira basin witnessed continuous development accompanied by subsidence wherein lithopackages of Bonai–Kendujhar Iron-ore Belt were deposited, Western Gurundia Basin is marked by a hiatus after the deposition of Gurundia quartzite and mafic volcanics in a shoreline to shallow marine environment. Darjing Group of rocks deposited as platformal package over Gurundia, Koira groups and BGC. Litho packages of Koira, Gurundia and Darjing groups exhibit structural unity as they co-deformed during Iron ore orogeny. The first deformation phase has led to a series of NE–SW to ENE–WSW trending low plunging overturned folds with southeasterly vergence. The second deformation, near coaxial with the first, has led to low northerly plunging open folds with steep northwesterly dipping axial planes. BGC occupies the core of a major second-generation fold with volcano-sedimentary sequence draping around it. It is proposed to put them under Iron Ore Super Group (IOSG), where IOGs (Koira and Gurundia groups) represent the lower part and Darjing Group as the upper part. Research Highlights: IOSG consists of IOGs (Koira and Gurundia groups) and Darjing Group as per present observation. Volcano sedimentary litho packages of IOG were deposited in two distinct basins (Koira and Gurundia basins) developed over BGC in a continental shelf-slope facies. Darjing Group deposited all over Gurundia and Koira groups and BGC after a hiatus which is marked by polymictic basal conglomerate. All the litho members of IOSG were co-deformed during Iron-Ore Orogeny (during the formation of Ur) and exhibit two distinct phases of folding as observed from field and this is reported for the first time with an attempt to bring Darjing group within Iron Ore Supergroup (IOSG). [ABSTRACT FROM AUTHOR]