Basin stratigraphy, sea‐level fluctuations and their global tectonic connections—evidence from the Proterozoic Cuddapah Basin

Abstract

The Cuddapah Supergroup succession can be divided into four unconformity‐bound sequences, namely, the Papaghni, Chitravati, Srisailam and Kurnool groups and formation representing four major cycles of sedimentation. The oldest sequence, the Papaghni Group is represented by fan‐delta, prodelta and shallow shelf deposits. The rifting stage of the basin evolution is attested by the immature delta succession deposited as a major fault‐controlled basin evolution, and was followed by the early subsidence stage. Basement uplift and a hiatus in deposition follows the first cycle of sedimentation. The Chitravati Group, representing the second cycle of sedimentation, consists of mature sandstones separated by a heterogeneous shale–sandstone–dolomite interval. The third cycle starts with the deposition of widespread coastal fluvial to shallow marine sandstone of the Srisailam Formation, and the fourth cycle is represented by the Kurnool Group consisting of conglomerates, feldspathic sandstones, supermature quartzarenites, minor shale and carbonates. Each cycle represents a rifting phase followed by a stable subsidence stage when the basin evolved into a large epicontinental sea. The supermature Gandikota Quartzite of the Chitravati Group and the Paniam Quartzite of the Kurnool Group represent relative sea‐level fall and forced regression. The siliciclastics in each of the sequences display signatures of macrotidal sedimentation pointing to open ocean connection. The sequences further display signatures of passive margin sedimentation with multiple events of carbonate‐shale rhythmite deposition. Mafic flows and dykes in the Papaghni and Chitravati groups reflect thermal anomalies associated with phased crustal extension; successive extensional phases were punctuated by basin inversion. Extensive and pulsed development of epicontinental seas as recorded in the Cuddapah sequences in the south Indian craton, possibly reflect global sea‐level changes associated with supercontinent (eg. Columbia in the Palaeoproterozoic) break‐up and assembly. Copyright © 2012 John Wiley & Sons, Ltd.