Paleomagnetism of Bhander Sediments from Bhopal Inlier, Vindhyan Supergroup

Abstract

Paleomagnetic investigations have been carried out on poorly determined radiometric age controls of Bhander sandstones within the vicinity of Bhopal Inlier of the Upper Vindhyan Supergroup. Available ages assigned to the Upper Vindhyan sequence range from Cambrian to the Mesoproterozoic and are derived from a variety of sources and methods. Paleomagnetic data generated from the Bhander Group of Bhopal Inlier yielded a mean declination of 357° and mean inclination of 58° (k=17.69, α95 = 16.38) with a Virtual Geomagnetic Pole (VGP) at 74° N, 69.0° E. This pole position is falling close to the Malani Igneous Suite (MIS) mean palaeomagnetic pole of 67.8° N and 72.5° E (A95=8.8°) by Gregory et al. (2009). The results obtained from this study and previous work on the 1073 Ma Majhgawan kimberlite, as well as detrital zircon geochronology of the Upper Bhander sandstone suggest that the Upper Vindhyan sequence may be older than is commonly thought earlier.

Chapter 6 Proterozoic Vindhyan Basin: configuration and evolution

“…A sharp upward transition from carbonates to siliciclastics everywhere across this surface reflects a basin-wide regression of the sea (Bose et al 2001). The upper age limit of the Supergroup, on the other hand, is more controversial; the previous general consensus was 600 Ma (Ray et al 2003;Ray 2006), while some recent workers suggest that it could be 900-1000 Ma (Malone et al 2008;Gopalan et al 2013;Venkateshwarlu & Rao 2013). The upper age limit of the Supergroup, on the other hand, is more controversial; the previous general consensus was 600 Ma (Ray et al 2003;Ray 2006), while some recent workers suggest that it could be 900-1000 Ma (Malone et al 2008;Gopalan et al 2013;Venkateshwarlu & Rao 2013).…”

Detrital zircon U-Pb ages of Proterozoic and Cretaceous sandstones of Narmada region in Central India: Implications for provenance and the closure age of the Vindhyan Basin

“…However, detrital zircon geochronological data from the Upper Vindhyan sandstones are available and generally show a lack of zircons younger than 1000 Ma, evidence that has served as a pointer to the closure of the Vindhyan Basin at ~1000 Ma (Chakraborty et al, 2020;Malone et al, 2008;McKenzie et al, 2011;Turner et al, 2014). Additionally, paleomagnetic evidence has also been used to suggest the termination of Vindhyan sedimentation at the end of the Mesoproterozoic (Malone et al, 2008;Meert et al, 2013;Turner et al, 2014;Venkateshwarlu and Rao;. In contrast to detrital zircon geochronology, other radiometric dates such as Pb-Pb and Sr-isotopic ages suggest that the deposition of the Upper Vindhyan succession continued until at least ~800 Ma (George et al, 2018;Gopalan et al, 2013;Ray et al, 2003;Srivastava and Rajagopalan, 1988).…”