Deformation and metamorphic history of the Singhbhum Craton vis–à–vis peripheral mobile belts, eastern India: implications on Precambrian crustal processes

抄録

The Singhbhum Craton (SC) of eastern India grew and evolved throughout the Precambrian era with a spectacular yet cryptic record of the early Earth processes. An extensive study on geochemistry, metamorphism, deformation, geochronology, and sedimentation of the rocks of the craton produced a large database which is described and synthesized here to build up a deformation and metamorphic history of the craton right from the Eoarchean time. Altogether seven orogenic episodes have been identified from the SC and its margins spanning from Paleoarchean to end–Neoproterozoic. Of these, the earlier two Paleo–Mesoarchean orogenic episodes (~ 3.3 and ~ 3.1 Ga) are confined within the cratonic core and were instrumental in building up of the framework of the Archean nucleus in SC. The Neoarchean event (~ 2.8 Ga) is marked by thrusting of the granulite–grade lower crust of the SC, the Rengali Province (RP), along its southern margin. Later three Proterozoic orogenic events (~ 1.8, ~ 1.6–1.5, and ~ 1.0 Ga) left imprints along the northern margin of the SC. Among these, the Grenvillian (~ 1.0 Ga) event was most pervasive, which remobilized the northern fringe of the Singhbhum Granite massif developing thick–skinned thrust belt–like structures within the narrow northern belt. Active tectonics later shifted again to the southern margin with the last orogenic event (~ 0.5 Ga) being marked within the RP resulting from oblique docking of the Eastern Ghats Belt (EGB) against the RP–SC. Based on this long and winding history, we also discussed the possible tectonic scenarios that eventually shaped the present configuration of the craton.