Cyclic sedimentation and classification of the Papaghni group of sediments, Cuddapah Basin, Andhra Pradesh

The Mesoproterozoic Papaghni Group in the Cuddapah basin of southern Andhra Pradesh comprises mainly arenaceous, argillaceous and calcareous sediments. These sediments occur in sequences that are mappable on large scale (1:5000) and the sequences are identified by unconformities which are recognised by conglomerate/breccia beds in Vempalle Formation (Papaghni Group). Each sequence starts with near-shore arenaceous and argillaceous sediments, and ends up with relatively deeper marine chemical precipitate, viz. dolomitic sediment, with these three constituting one cycle of sediments. The thickness of each cycle ranges from about twenty meters to hundreds of meters and three such cycles of sedimentation are identified. On the basis of the identification of cyclic sedimentation and bounding unconformities, it is proposed that the Vempalle Formation of Papaghni Group may be classified into Lower, Middle and Upper members, which denote recurrence of similar depositional settings during the Vempalle sedimentation.