Petrogenesis and geochronology of the Arkasani Granophyre and felsic Dalma volcanic rocks: implications for the evolution of the Proterozoic North Singhbhum Mobile Belt, east India

Abstract

-The North Singhbhum Mobile Belt (NSMB) is a 200 km long, curved Proterozoic foldthrust belt that skirts the northern margin of the Archean Singhbhum Craton of NE India. The Singhbhum Shear Zone (SSZ) developed between the Dhanjori and Chaibasa formations near the southern margin of the NSMB and represents an important Cu-U-P metallotect. A SHRIMP U-Pb zircon date of 1861 ± 6 Ma, obtained for the syn-to post-kinematic Arkasani Granophyre that has intruded the SSZ, provides a minimum age for the prolonged tectonic activity and mineralization along the SSZ and for the time of closure of the Chaibasa and Dhanjori sub-basins. The Dalma Volcanic Belt, a submarine rift-related bimodal mafic-felsic volcanic suite, forms the spine of the NSMB. A SHRIMP U-Pb zircon igneous crystallization date of 1631 ± 6 Ma was obtained for an unfoliated felsic volcanic rock from the base of the Dalma volcanic sequence. These new findings suggest that the different sub-basins in the NSMB evolved diachronously under contrasting tectonic environments and were juxtaposed during a later orogenic movement.

The geological evolution of the Gangpur Schist Belt, eastern India: Constraints on the formation of the Greater Indian Landmass in the Proterozoic

“…Tectonic discrimination diagrams for granites and basalts: (a) Zr versus Ga/Al diagram for granites (Whalen, Currie, & Chappell, ) showing that the CGC granites/gneisses as well as the Upper Bonai and Gangpur Group granites/pegmatites have S‐type affinity. Note that the felsic rocks of the Dalma metaigneous belt (data from Bhattacharya et al., ) are not A‐type as was claimed by the authors; (b) Rb versus Nb+Y diagram for granites by Pearce et al. () with the CGC granites/gneisses and the Upper Bonai and Gangpur Group granites/pegmatites displaying affinities to volcanic arc or syn‐collisional granites.…”

“…() with the CGC granites/gneisses and the Upper Bonai and Gangpur Group granites/pegmatites displaying affinities to volcanic arc or syn‐collisional granites. The Dalma felsic volcanic rocks also display arc signature (data from Bhattacharya et al., ); (c) Th/Yb versus Nb/Y diagram of Pearce () with the Gangpur Group metagabbro and Dalma basalts (data from Chakraborti & Bose, ; Roy, Sarkar, Jeyakumar, Aggrawal, & Ebihara, ) displaying arc signatures…”

“…1.64 Ga age of the Kuilapal granite (Sengupta et al., ) and the c . 1.63 Ga age of felsic volcanic rocks of the Dalma metaigneous belt (Bhattacharya, Nelson, Thern, & Altermann, ; Reddy & Evans, ). It appears reasonable, therefore, to suggest that the Upper Bonai/Darjing and the Gangpur Groups of rocks are the westward extensions of the northern and southern domains of the North Singhbhum Mobile Belt respectively.…”

Geochemical and Sm–Nd isotopic characteristics of the Late Archaean-Palaeoproterozoic Dhanjori and Chaibasa metasedimentary rocks, Singhbhum craton, E. India: Implications for provenance, and contemporary basin tectonics

“…A difference in opinion exists on various aspects of the SSZ, particularly on its lateral continuity, age of shearing, width and the extent of the rocks that it has affected (cf. Mukhopadhyay, 1984;Saha, 1994;Saha, 1998,2000;Sengupta and Chattopadhyay, 2004;Pal et al, 2011;Banerjee and Matin, 2013;Bhattacharya et al, 2014). Mazumder et al (Mazumder et al, 2012a(Mazumder et al, ,b, 2014 presented an updated critical synthesis of the Palaeoproterozoic geological history of the Singhbhum craton and the status of the SSZ that interested reader may find useful.…”

“…No direct age data is yet available from the metasedimentary rocks of the Palaeoproterozoic supracrustal successions (cf. Mazumder, 2005;Mazumder et al, 2012a) except the Chandil Formation occurring to the north of the Dalma volcanic belt (magmatic zircon SHRIMP concordia age ∼1600 Ma; Nelson et al, 2007;Reddy et al, 2009;Bhattacharya et al, 2014, Fig. 1).…”