Abstract

Krishna-Godavari basin is located at the centre of East Coast of Peninsular india. The basin represents a fully developed passive margin setup resting on the eroded Permo-Triassic rift fill sequence. Early drift phase is represented by deltaic facies of the Krishna-Godavari rivers. East Godavari subbasin covers partly the present day onland and offshore parts. Sequence stratigraphy study of the Miocene sediments in the area enables to understand the depositional regimes prevailed during the Miocene perio. The Miocene sedimentary sequence in the study area has been subdivided into twelve 3rd order sequences, sequence N1 to sequence N12. The sequences N1 to N3 were deposited on top of the Oligocene unconformity and wedge out against the basinal flank beyond the study area. The sequences N4 to N12 are correlated on the seismic data and interpreted in the study area. Sequences N4 to N6 represent the Lower Miocene depositional regime. The Middle Miocene is represented by sequences N7 to N9 and the Upper Miocene by N10 to N12 sequences in the study area. Lithologically the Miocene sequence consists of sandstone, shale, claystone and occasional limestones. The sequences N4 to N10 host the Ravva Formation equivalent. The sequences N11 and N12 host the Rajahmundry Sandstone. The sequence stratigraphic model of the Miocene sediments in the area depicts the coastal progradation from the point of maximum updip transgression during Lower Miocene deposition. Depositional styles and patterns within system commonly change as base-level rise begins to dominate. Progradational lower parts of genetic sequences are typified by greater fluvial domination of delta systems and by strand plains. Retrogradational upper parts of sequences display greater wave reworking of delta lobes.