Outcrop signatures of relative sea level fall on a siliciclastic shelf: Examples from Rewa Group of Proterozoic Vindhyan basin

Journal of Earth system science

Partha Pratim Chakraborty1¹ 

[1] Department of Applied Geology, Indian School of Mines, Dhanbad 826 004, India.$$

关键词: Neoproterozoic;    Rewa Group;    paleoenvironment;    sea level;    regression.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

The Rewa Group of the Vindhyan Supergroup in the Son valley begins with a thick (∼200m) dominantly shaly,shelfal succession,occurring between the Dhandraul Formation of the Kaimur Group (fluvial sandstone)below and Drammondganj Formation of the Rewa Group (marginal marine sandstone)above.Such a stratigraphic disposition indicates a sharp rise in relative sea level at the onset of Rewa sedimentation,inducing a shelfal depth to the Vindhyan basin.However,a number of wedge-shaped,sandstone/conglomerate bodies (maximum thickness 23.5 m)occur at multiple stratigraphic levels within the aforesaid deeper water shale succession,which appear to be of much shallow water origin representing regressive deposits.Though these bodies do not define a single physically continuous unit,either vertically or laterally,they are still designated by a single term ‘Asan Sandstone ’in the literature.On the other hand,the encasing shelfal shales are termed as Panna and Jhiri Shales,in accordance with their occurrence below or above the so-called ‘Asan Sandstone ’.The present study reveals that in different sections spread over the Son valley,there are several discrete regressive wedges occurring vertically,and their depositional environment is also variable,ranging between braided fluvial,shoreface fan and braid delta.The features common to most of the regressive coarser clastic bodies are:invariable presence of deeper water,shelfal shale below (Panna or Jhiri);

【 授权许可】

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