Tectonostratigraphy and depositional patterns in Krishna Offshore Basin, Bay of Bengal

The Krishna-Godavari Basin along the east coast of India covers the deltaic and interdeltaic areas of the Krishna and Godavari rivers and extends into the offshore (Figure 1). This basin is situated along the shoulder of a rifted passive continental margin which developed during the separation of India from Antarctica in the Late Jurassic. This rifting episode is superimposed on an earlier northwest-southeast “Gondwana graben trend” such as the Pranhita-Godavari graben (Figure 2a), which extends from onshore into the Krishna-Godavari Basin. This is an earlier prerift depositional episode onto Precambrian crystalline basement which commenced in the Early Permian and continued through the Middle Jurassic. The Late Jurassic rift episode caused mechanical extension along the eastern margin leading to the formation of northeast-southwest horst and graben features. Based on Bouguer gravity data, Murty and Ramakrishna (1980) recognized different tectonic elements (Figure 2b) such as Krishna graben, Bapatla horst, West Godavari subbasin (including the median Kaza-Kaikalur horst), Tanuku horst, and East Godavari subbasin (including Narasapur-Yanam high).