Neoarchean–Paleoproterozoic stratigraphy of the Dhanjori basin, Singhbhum Craton, Eastern India: And recording of a few U–Pb zircon dates from its basal part S.K. Acharyya a, * , Anupendu Gupta b , Y. Orihashi c a Department of Geological Sciences, Jadavpur University, Kolkata 700 032, India b BB 45/3, Salt Lake, Kolkata 700 064, India c Earthquake Research Institute, University of Tokyo, Bunkyo, Tokyo113-0032, Japan article info Keywords: U–Pb zircon dates Dhanjori basin stratigraphy Neoarchaean QPC-bearing Phuljhari Formation Mayurbhanj Granite Singhbhum Craton abstract The stratigraphy of the Dhanjori basin placed at the northeastern margin of the Paleo-Mesoarchean Sing- hbhum Craton has been revised. A mainly quartz-pebble conglomerate (QPC) and volcani-clastics bearing unit at the base of the Dhanjori basin and intruded by the Mayurbhanj Granite, has been named Phuljhari Formation. The Dhanjori volcani-sedimentary sequence with quartzite–polymictic conglomerate at its base, disconformably overlies the Phuljhari Formation and non-conformaby over the Mayurbhanj Gran- ite. The Dhanjori Group is inferred to broadly range in age from 2.6–2.1 Ga. Detrital zircons from QPC belonging to the Phuljhari Formation have yielded oldest chemical ages of 3.09–3.04 Ga thus fixing the upper age limit of the formation. The 3.09 Ga old zircons recovered earlier from the Mayurbhanj Granite, which is intrusive into the relatively younger Phuljhari Fm., therefore appears to be xenocrystic in nature. A fine grained variety of the Mayubhanj Granite, close to its intrusive contact with the Phuljhari Fm., was sampled during the present study. It has recorded strong impress of acid magmatic event around 1.0– 0.8 Ga by its lower intercept and an upper intercept age of 2.8 Ga. The latter might record the inherited age of protolith to the Mayurbhanj Granite and correspond to widespread granite magmatic activity affecting the margin of the Singhbhum Craton. Signature of 1.0–0.08 Ga old thermal perturbation also affected lower parts of the Dhanjori basin and the Singhbhum Shear Zone. Detrital Au–U bearing QPC in the Phuljhari Formation represent Neoarchean sedimentation at the margin of the peneplained craton. The Dhanjhori Group comprising mafic–ultramafic volcanics and siliciclastics was hosted in rift induced intracratonic basin around Neoarchean–Palaeoproterozoic threshold. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The eastern segment of the Indian Precambrian shield includes one of India’s older records of Paleoarchean crust, known as the Singhbhum North Orissa Craton or simply the Singhbhum Craton (Fig. 1a). The craton is primarily composed of the Singhbhum Gran- ite batholith (SBG) and narrow greenstone belts associated with Banded Iron Formations called the Iron Ore Group (IOG). The SBG contains enclaves of meta-sedimentary rocks (referred to as the Older Metamorphic Group or OMG) and TTG gneisses (referred to as the Older Metamorphic Tonalite Gneiss or OMTG) (Saha, 1994). The OMG and OMTG rocks from well studied Champua and Onlajori areas, located at the western and northeastern part of the craton (Fig. 1a) range in age from 3660 to 3330 Ma (Pb–Pb on WR, Moorbath et al., 1986; Sm–Nd on WR, Sharma et al., 1994; Pb–Pb on zircon, Goswami et al., 1995; Pb–Pb on WR, Ghosh et al., 1996; Pb–Pb on zircon, Mishra et al., 1999). In course of our recent studies on the least examined northern area of the craton, zircon recovered from TTG type gneisses (OMTG) has yielded new U–Pb ages of 3448 ± 19 Ma and 3527 ± 17 Ma (Acharyya et al., 2010). The SBG was emplaced during two distinct phases – the older phase (SBG-A) from 3440 to 3330 Ma and the younger phase (SBG-B) from 3200 to 3050 Ma. Acid volcanics from the southern IOG belt have been dated at 3507 ± 2.3 Ma (U–Pb on zir- con by SHRIMP; Mukhopdhyay et al., 2008), which is older than the two SBG phases, as well as, the major and younger component of the OMTG. Therefore, OMG enclaves, considered as the oldest supracrustal rocks in the region might be derived from IOG rocks (Acharyya et al., 2010). The Tamperkola and the Mayurbhanj Gran- ite plutons occurring close to the western and eastern margins of the Singhbhum Craton provide clear evidence of Neoarchean (3.0–2.8 Ga) magmatic activity (Saha et al., 1977; Mishra et al., 1999; Bandyopadhyay et al., 2001). 1367-9120/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2010.04.023 * Corresponding author. E-mail address: skacharyya@gmail.com (S.K. Acharyya). Journal of Asian Earth Sciences 39 (2010) 527–536 Contents lists available at ScienceDirect Journal of Asian Earth Sciences journal homepage: www.elsevier.com/locate/jseaes