Storm Deposits in the Late Proterozoic Lower Bhander Sandstone of Vindhyan Supergroup Around Maihar, Satna District, Madhya Pradesh, India

Abstract

ABSTRACT Intertidal late Proterozoic Lower Bhander Sandstone around Maihar, Satna district, Madhya Pradesh, characteristically displays three orders of sandstone/shale alternations. The lowest order millimeter-thick alternations can be explained as related to tidal rhythms. The second-order alternations in the range of centimeters appear to be related to processes with periodicities greater than tidal rhythms-storm/calm condition. That these centimeter-thick sandstones are possible product of suspension-laden storm surge ebb current is supported by 1) the presence of various types of tool marks, scour marks, and load structures, 2) the presence of sharp, erosional bases and diffused tops, 3) gradual transition from parallel lamination to ripple lamination up the sequence, 4) sporadic preservat on of larger dune bedforms, and finally by 5) consistent seaward directed paleocurrent. This contention is further strengthened by the fact that the vertical lithofacies change is nonmarkovian in character. The uncommon overthickened first order sandstones in the range of decimeters are composite in character and appear to be product of storms coming at close intervals or of complete erosion of mud interlayers.