A new palaeobiological assemblage from the Son Valley Bhander Group and its implications on the age of the upper Vindhyans of India

Abstract

The present study discusses the biostratigraphically significant new fossil assemblage recovered from the three stratigraphic units of the Bhander Group of the Vindhyan Supergroup, exposed in the Son Valley, India. The assemblage comprises vase-shaped like microfossils (possible VSMs) — Cycliocyrillium simplex, C. torquata, Bonniea pytinaia, B. dacruchares, scale microfossils, and cyanobacterial forms recorded in black bedded/lensoid chert associated with the Bhander Limestone. Late Ediacaran Leiosphere Palynoflora (LELP) and other associated organic-walled microfossils (Leiosphaeridia spp., such as L. jacutica, L. crassa, L. tenuissima, L. minutissima, and Ostiana microcystis) are noted in the Sirbu Shale. Charniodiscus-like Ediacaran megafossil is recorded in the Maihar Sandstone the youngest litho-unit of the Bhander Group. An assemblage of possible VSMs, acritarchs, and Ediacaran-like megafossil compliments the previous reports of the Ediacaran-aged fossils, such as Arumberia banksi, Beltanelliformis minuta and other fossils recovered from the Bhander Group and used to constrain the age of the Bhander Group. The biostratigraphic significance of the fossil assemblage has been discussed. The present study provides a better age constraint of the Bhander Group suggesting that this group continuously received sediments for deposition into the Ediacaran Period (635–538 Ma).