Gondwana Lithostratigraphy of Peninsular India

Abstract

The controversy regarding the stratigraphic interpretation of the Indian Gondwana succession in the Peninsular Basins has continued for more than a century, with the exception of the Damodar and Satpura Basins. While the stratigraphic reconstruction in Damodar and Satpur was based on the order of superposition of strata, elsewhere the relative ages were based on paleontological evidence that disregarded various physical criteria including the order of superposition. Overlying the Precambrian crystalline basement, the Gondwana succession of late Permian to early Jurassic age can be classified into four sedimentary facies; a glaciogenic facies (Facies A), a coal-bearing facies (Facies B), a red shale-sandstone facies (Facies C) and a hill-forming coarse sandstone-conglomeratic facies (Facies D). The stratigraphic order of these four facies in ascending order from Facies A at the bottom to Facies D at the top is well established in the Damodar and Satpura regions. In both areas, Facies D overlies the underlying older sediments as well as the crystalline basement with a pronounced unconformity. However, in the Pranhita-Godavari and Son Basins (and elsewhere) the stratigraphic relations between Facies B, Facies C and Facies D are controversial. One such enigma is where the sequence of Facies C and Facies D are repeated several times in the geological column. This interpretation contrasts with the supposed genesis of climatically controlled lithic fill in Gondwana Basins. Overturning the standard stratigraphic relation between Facies C and Facies D was based on fragmentary fossil evidence where the Lower Gondwana flora seems to be present in Upper Gondwana rocks. Turning the stratigraphy upside down was done without establishing the order of superposition between strata. Throughout the 20 th century, most stratigraphers working in the Pranhita-Godavari and Son Basins worked within a fossil-based stratigraphic paradigm. This resulted in still more confusion, the magnitude of which can be appreciated as one browses through various interpretations presented in innumerable publications. In this paper, we attempt to offer a lithostratigraphic interpretation of the Peninsular Gondwana Basins based only on physical criteria such as lithological association, their petrographical characteristics and the most fundamental tool of stratigraphy, “the order of superposition”.