Tidal Flat Sedimentation in Bairenkonda Formation of the Tirumala Hills, Southwestern Part of the Cuddapah Basin, Andhra Pradesh

Abstract

Siliciclastic sediment succession of the Bairenkonda Formation of the Proterozoic Cuddapah Supergroup overlies the granite-gneiss of the east Dharwar craton along a nonconformity in the Tirumala hills. Basin fill sediments are now classified in ascending order into three lithofacies assemblages namely; lower cross-stratified sandstone (CSS); middle sand-dominated heterolithic (MH) and upper shale-dominated heterolithic (UH) associations. Paleocurrent was towards east in CSS; bi-directional in MH and UH. Provenance was in west. Lithofacies attributes have indicated that the CSS was deposited along foreshore/supratidal environment where sedimentation had taken place under the combined influence of waves, storms and tides. The succeeding MH assemblage represents deposition in channels and distributaries over sandy intertidal flats. The upper mud dominated heterolithic assemblage (UH) was deposited in mixed intertidal to subtidal flats. Accordingly, the depositional milieu contemplated for the Bairenkonda Formation is tidal flat in shallow marine environment. Siliciclastic sediments thus deposited were uplifted due to basin inversion to form the mighty Tirumala hills in southwestern part of the Cuddapah basin, Andhra Pradesh.