Shallow marine glauconitization during the Proterozoic in response to intrabasinal tectonics: A study from the Proterozoic Lower Bhander Sandstone, Central India

•Glauconitization in shallow water epeiric sea.•Role of Intrabasinal tectonics for development of paleo-redox condition.•Small progradational packages within overall fining up cycle. Glauconite forms authigenically by the replacement of quartz and feldspar substrates within the Precambrian Lower Bhander Sandstone (LBS) of the Vindhyan Basin. The glauconite exhibits consistently high K2O (7.08–8.62 wt%) and low to moderate TFe2O3 (6.20–18.5 wt%). The X-Ray Diffraction study reveals an evolved to highly evolved glauconitic mica structure. The deposition of mudstone-dominated LBS took place in a shallow marginal marine environment within a low gradient epeiric sea. The overall fining upward succession of the LBS comprises multi-storied, meter scale progradational cycles defined by red mudstone and sandstone–siltstone alternation in ascending order. The repetitive cycles indicate recurrent low-magnitude basin subsidence of the epeiric seafloor. Slump folds and slide planes, associated with the wedge-shaped mud pebble conglomerate, mark each episodes of basin subsidence. The glauconite occurs within sandstone and the sandy matrix of a wedge-shaped conglomerate at the base of a shallowing upward cycle which starts with a grey colored mudstone. The enrichment factors of redox-sensitive elements elucidate sub-oxic depositional condition during the glauconitization. The redox-sensitive element ratios (V/Cr, V/Sc) corroborates the sub-oxic depositional condition for the glauconitic interval and oxic environment for the encasing sediments. The formation of glauconite in the LBS corresponds to the deepening of the basin in response to the tectonic subsidence. The meter scale progradational cycles, recording the transition from suboxic to oxic conditions, corresponds to tectonically-induced deepening and subsequent filling. This study recognizes the significance of intrabasinal tectonics in facilitating suitable redox conditions for the glauconitization process within Proterozoic shallow epeiric sea deposit.