Origin of Fining-Upward Cycles in the Early Permian Barakar Formation of Gondwana Basins of Peninsular India

• Published in: Journal of geosciences, Osaka City University Osaka City University, 2008, Vol.51, p.21-26
• Main Authors: Maejima, W, Tewari, R C, Hota, R N
• Format: Article
• Language: English
• ISSN: 0449-2560

The early Permian Barakar Formation of Gondwana basins of Peninsular India varies from 300-1100 m in thickness. It is composed of fining-upward cycles of conglomerate/very coarse- to coarse-and medium-grained sandstone arrow right interbedded fine-grained sandstone-shale arrow right shale arrow right coal. Among these, some of the fining-upward cycles are relatively thin (6-8 m), containing a greater amount of coarse grade members and laterally impersistent beds of fine clastics and coal. But most of the fining-upward cycles are thick (10-20 m or more) and composed of subequal amounts of coarse and fine grade members. The coal beds at the top of these cycles show sharp lower contact and are laterally persistent for several tens of kilometers. These cycles correspond to deposition under differential subsidence rather than channel migration as suggested by earlier workers. The alternate phases of rapid and slow subsidence of depositional basin through time may account for the development of such fining-upward cycles.