Palaeoproterozoic sedimentation on the Singhbhum Craton: global context and comparison with Kaapvaal

Abstract

Abstract The Singhbhum Craton has a limited Palaeoproterozoic supracrustal record, which suggests a three-part history, comprising: a long period of high freeboard and palaeosol formation on granitoids; subsequent rift-related mafic–ultramafic volcanism and subordinate sedimentation ( c. 2.25–2.1 Ga: Dhanjori and Jagannathpur basin-fills; possibly also Simlipal, Malangtoli and Ongarbira basin-fills), which overlapped locally with mafic soil formation; and a major regression at around 2.0 Ga. Following a long hiatus, the approximately 1.6 Ga Dhalbhum–Dalma succession was laid down, probably under continental conditions. This rather truncated record stands in contrast to the chronologically and geographically much more widespread supracrustal basin-fills of the Kaapvaal Craton, and there appears to be an overall poor comparison between these two early Precambrian crustal blocks. However, on Kaapvaal, three analogous events are identified: widespread approximately 2.2 Ga mafic volcanism, followed by a well-developed palaeosol and a major transgression prior to 2.05 Ga. The three shared events between the two cratons are compatible with the postulate of a global, approximate 2.45–2.2 Ga shutdown of magmatic and tectonic geodynamics, with the origin of the triumvirate directly reflecting its resumption again after about 2.2 Ga. We recognize here that a large diversity of views on Singhbhum's geodynamic history exists, predicated on a lack of precise geochronology and commonly poor outcrops, and the current hypotheses are presented with these factors in mind.