Neoarchean tectonothermal imprints in the Rengali Province, eastern India and their implication on the growth of Singhbhum Craton: evidence from zircon U-Pb SHRIMP data

A detailed zircon U-Pb (SHRIMP) geochronological study of the amphibolite to granulite-grade rocks of the Rengali Province of eastern India records the growth history of the southern margin of the Singhbhum Craton. Pelitic and mafic granulites from the gneissic belt exhibit contrasting styles of metamorphism. Zircon of the pelitic granulites from the eastern segment yields c. 3528-3064 Ma detrital ages. Charnockitic gneiss from the eastern segment has protolith age of 3058 +/- 15 Ma while that from the central segment has protolith age of 2861 +/- 30 Ma. The latter rock records high-grade metamorphism at 2818 +/- 15 Ma. Hornblende gneiss from the central sector has a protolith age of 2828 +/- 9 Ma. Deformed leucogranite in the central and undeformed granitoid in the eastern segment were emplaced at 2807 +/- 13 and 2809 +/- 13 Ma respectively. The protolith of felsic gneiss from the central sector was emplaced at 2776 +/- 24 Ma. Most of the zircon samples contain overgrowths of c. 2500 Ma, inferred to be the age of reworking of the gneissic belt. Our data suggest that the Rengali Province evolved as an orogenic belt in the Neoarchean time (c. 2800-2500 Ma) during southward growth of the Singhbhum Craton. These tectonothermal imprints at the margin of the Singhbhum Craton are possibly related to its inclusion within the supercontinent Ur.