Multiple tectonometamorphic imprints in the lower crust: first evidence of ca. 950 Ma (zircon U-Pb SHRIMP) compressional reworking of UHT aluminous granulites from the Eastern Ghats Belt, India KAUSHIK DAS 1 * , SANKAR BOSE 2 , SUBRATA KARMAKAR 3 , DANIEL J. DUNKLEY 4 and SOMNATH DASGUPTA 5 1 Department of Geology, Bengal Engineering and Science University, Howrah, India 2 Department of Geology, Presidency College, Kolkata, India 3 Department of Geological Sciences, Jadavpur University, Kolkata, India 4 National Institute of Polar Research, Tokyo, Japan 5 Indian Institute of Science Education and Research, Kolkata, India Integrated structural, petrological and geochronological study on a suite of granulites from the central part of the Eastern Ghats Belt (EGB), India unveils polyphase tectonothermal evolution. We document (a) M 1 ultrahigh temperature (UHT) metamorphism (10008C at 6.5–8.5 kbar) on an anticlockwise P–T trajectory simultaneously with early deformations D 1 –D 2 involving partial melting, (b) cooling down to  8008C, 6 kbar that produced a variety of coronae/symplectites (M 1R ), (c) an unrelated compressional orogeny (D 3 ) that produced deep crustal shears and mylonitic foliation (S 3m ) at low angles to D 1 –D 2 structures and was associated with slight loading, and possible partial melt extraction under granulite facies condition (M 2 7 kbar, 8508C), and (d) localized retrogression (M 3 ) in the presence of melt accompanying D 4 deformation. This is the first record of the prograde P–T path of the superimposed granulite facies metamorphism in the EGB. U-Pb SHRIMP data of zircon preserves an inherited grain domain of ca. 1700 Ma ( 207 Pb- 206 Pb age) that traces back the history of EGB with a lineage of the Mesoproterozoic supercontinent, Columbia. The UHT metamorphosed (peak M 1 at ca. 1000 Ma) and subsequently cooled crustal segment (M 1R ) was subjected to strong tectonothermal reworking (M 2 ) along a clockwise P–T path at 953 þ 6 Ma (concordia age) that partially exhumed the rocks to mid-crustal levels. A later fluid-induced retrogressive event vis-a `-vis melt crystallization occurred at ca. 900 Ma ( 207 Pb- 206 Pb age). The post-peak evolution reveals striking similarities with those recorded in the rocks of the Rayner Complex of east Antarctica, thereby strengthening the notion of Indo-Antarctic correlation as part of Rodinia. Copyright # 2010 John Wiley & Sons, Ltd. Received 27 November 2009; accepted 29 March 2010 KEY WORDS deep crustal reworking; Eastern Ghats Belt; India; UHT aluminous granulites; zircon U-Pb SHRIMP ages Supporting information (supplementary tables S2-S6) may be found in the online version of this paper. 1. INTRODUCTION Many of the ultrahigh temperature (UHT, > 9008C, Harley, 1998; Kelsey, 2008) metamorphosed terrains record a nearly isobaric cooling retrograde P–T trajectory (reviewed in Harley, 1989, 1998, 2004; see also Santosh et al., 2007; Santosh and Kusky, 2010; Liu et al., 2011). Two prominent examples include the Archaean Napier Complex in east Antarctica (Harley and Hensen, 1990; Harley, 2003) and the Proterozoic Eastern Ghats Belt in India (Dasgupta and Sengupta, 2003). Exhumation of these isobarically cooled terranes occurred in response to unrelated later orogenic events. In case of the Napier Complex, the Rayner orogeny of broadly ca. 940–910 Ma age reworked the early granulites, records of which are found in marginal shear zones (Harley and Hensen, 1990; Kelly et al., 2000, references therein). Limited radiometric dates on the Eastern Ghats rocks show overprinting by ca. 1000–950 Ma orogeny on the early UHT granulites during a second granulite facies metamorphism characterized by near isothermal decompression during retrogression (Grew and Manton, 1986; Shaw et al., 1997; Mezger and Cosca, 1999; Dasgupta et al., 1994, 1995; Dasgupta and Sengupta, 2003). However, the prograde path of the second granulite GEOLOGICAL JOURNAL Geol. J. 46: 217–239 (2011) Published online 24 June 2010 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/gj.1246 * Correspondence to: K. Das, Department of Geology, Bengal Engineering and Science University, Howrah 711103, India. E-mail: kaushik.met@gmail.com Copyright # 2010 John Wiley & Sons, Ltd.