Braided-Fluvial Depositional Model of Late Triassic Gondwana (Mahadeva) Rocks of Son Valley, Central India: Tectonic and Paleogeographic Implications

About 800 m thick late Triassic Gondwana (Mahadeva) rocks of Son valley, central India are composed of pebbly to gritty, very coarse to coarse and medium sandstone, and thin to thick beds of grey, micaceous and red shale. Sandstone bodies are channel-shaped to sheet-Like and multistoreyed, characterised by large scale trough and planar cross-beds. Interbedded shale beds are laminated. Palaeocurrent analysis based on 192 measurements of trough cross-bedded cosets reveals northwesterly (321° ± 46°) palaeodrainage and palaeoslope throughout the late Triassic Gondwana sedimentation.

Lithofacies characters, nature and geometry of sedimentary structures and palaeocurrent attributes suggest that the late Triassic Gondwana rocks of the Son valley area were deposited by a widespread system of bed load (braided) streams which flowed dominantly from southeast to northwest. Indeed, there is uniformity in the northwesterly palaeolope during Permian and Triassic Gondwana sedimentation in this area. Implicitly, the Gondwana basin under study should have extended northward down the palaeoslope beyond its present limit across the north boundary fault (? Narmada - Son lineament).