| Abstract: | The southern boundary of the Singhbhum Craton witnessed multiple orogenies that juxtaposed thin slice of granulite suite of the Rengali Province against the low-grade granite-greenstone belt of the craton along the EeW trending Sukinda Thrust.The strong southerly dipping mylonitic foliation within the granulites along with the prominent down-dip mineral lineation,suggest a northerly-verging thrusting.Mylonitized charnockite at the contact zone contains enclaves of mafic and ultramafic granulite,whereas granitoid gneiss contains enclaves of pelitic granulite.Mafic granulite enclaves preserve an early(S1M)foliation that formed during D1Mdeformation.This rock,along with the host charnockite,were intensely deformed by the D2Mthrusting event and resulting S2Mfoliation development in both rock suites.Geothermobarometric and pseudosection analyses show that the garnet-clinopyroxene-plagioclaseorthopyroxene-ilmenite-quartz assemblage in mafic granulite was stabilized at high-pressure and temperature conditions(10 12 kbar,860 C)and was overprinted by a fine-grained assemblage of clinopyroxene-plagioclase hornblende that developed during decompression(down to 5.5e7.5 kbar).Matrix hornblende shows incipient breakdown to garnet-clinopyroxene-quartz intergrowth due to a granulite facies reworking.A contrasting P-T history is preserved in the pelitic granulite.The peak assemblage garnet-orthopyroxene-cordierite-quartz-rutile was stabilized at w6.0 kbar,730 C which resulted from heating of the mid crust magma during the D2Mthrusting.The contrasting P-T histories could result from the tectonic juxtaposition of lower-and mid-crustal section during the D2Mevent.Evidences of an early orogenic imprint within the mafic granulite imply involvement of deep continental crust during southward growth of the Singhbhum Craton. |
