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

Abstract

a b s t r a c tIn significant contrast to other cratonic blocks of India, the Singhbhum cratonic successions record continuous depositional record from the Palaeoarchaean to Mesoproterozoic. Although the sedimentary facies characteristics and mode of stratigraphic sequence building of the Dhanjori and Chaibasa Formations are well known, sedimentary geochemistry, provenance and tectonic milieu of deposition of these two formations are hitherto unknown. The current manuscript presents geochemical and Sm-Nd isotopic data from the Dhanjori and Chaibasa Formations for the first time and combine previous sedimentological data with the goal to expand the framework for understanding the depositional and tectonic setting of these two formations. The Sm-Nd isotopic data for the Chaibasa clastics is unambiguous with respect to provenance. Average ε Nd (t = 2.2 Ga) = −0.8 ± 1.0 and average Nd model age (TDM) = 2.51 ± 0.08 Ga with average 147 Sm/ 144 Nd ratios = 0.1114 ± 0.0041 for phyllites and quartzites indicate an extremely homogeneous source signature consistent with a late Archaean "juvenile" crustal provenance, possibly a dominantly upper crustal provenance. The Sm-Nd isotopic data from the older Dhanjori Formation also indicate broadly similar provenance as comparable lithologies in the younger Chaibasa Formation. Our Sm-Nd isotopic data is entirely consistent with the previous sedimentological data and confirms a terrestrial, riftdominated tectonic setting for the Dhanjori Formation (proximal sources, poorly mixed provenance) and a marginal marine to offshore setting for the more homogeneous Nd isotopic signature of the Chaibasa Formation (distal sources, well mixed provenance).

The Architecture and Evolution of the Singhbhum Craton

“…The Dhanjori succession, predominantly consisting of volcanics and volcaniclastic and siliciclastic sediments, unconformably overlies the granitoids of the SBG pluton. It may be subdivided into Upper and Lower Formations (Gupta, 1985;Mazumder and Sarkar, 2004;De et al, 2015). The Lower Dhanjori Formation consists of pebbly phyllite, quartzite and thin conglomerates with minor mafic-ultramafic intrusions and the Upper Dhanjori Formation consists of volcanics and volcaniclastic rocks with some quartzites and phyllites.…”

“…A semi-arid paleoclimate during the fluvial deposition is also inferred. On the basis of sediment characteristics and Sm-Nd isotopic data De et al (2015) suggested proximal sources and poorly mixed provenance with both mafic and felsic rocks. They further suggested a sedimentary provenance in a juvenile felsic Andean-type magmatic arc situated on the Archean basement.…”

“…Saha et al (2004) inferred that subduction-accretion processes operated during the mid-Archean in the Singhbhum Craton. For the mid-Archean Dhanjori Group, De et al (2015) suggested a sedimentary provenance in a felsic Andean-type magmatic arc.…”

Uraniferous paleoplacers of the Mesoarchean Mahagiri Quartzite, Singhbhum craton, India: Depositional controls, nature and source of >3.0Ga detrital uraninites

“…The age of the successions within the NSMB is yet to be well constrained. The ages of metamorphism, mineralization and granite emplacement within NSMB suggest sedimentation event between 2.7 to 2.1 Ga, deformation and mineralization events from 1.9 Ga to 1.0 Ga with a peak of deformation and mineralization at ~1.6 Ga (Mukhopadhyay, 2001;Gupta and Basu, 2000;Mahato et al, 2008;Mazumdar 2012;Pal et al, 2011;Pal and Rhede 2013;Prabhakar and Bhattacharya 2013;De et al, 2014).…”

Palaeoarchaean sedimentation and magmatic processes in the eastern Iron Ore Group, eastern India: A commentary

“…In significant contrast to other Indian cratonic blocks, the Singhbhum cratonic block bears an almost continuous Palaeoarchaean to Mesoproterozoic geological record (Mukhopadhyay et al, ; Saha & Mazumder, ; Mazumder et al, ; Nelson, Bhattacharya, Thern, & Altermann, ; Ghosh, Ghosh, & Mukhopadhyay, ; Van Loon & De, ). Although researchers have inferred the Palaeoproterozoic volcano‐sedimentary processes on the Singhbhum cratonic block (De et al, ; ; Mazumder, ; Mazumder & Arima, ; Mazumder & van Loon, ), the Archaean geological history is largely unknown (cf. Ghosh et al, ; Nelson et al, ).…”