CRETACEOUS SEDIMENTATION IN THE SUBSURFACE OF KRISHNA-GODAVARI BASIN

The NE-SW trending Krishna-Godavari Basin is located at right angles t o NW-SE treading Pranbita-Godavari graben ? towards the basin margin. From subsurface exploratory data obtained, it is inferred that NW-SE t rending Gondwana graben is extending underneath Krishna-Godavari Basin . In subsurface, the sedimentary sequence occurring in between the bas alt and the 'Red Bed' is demarcated as the Cretaceous sequence. This s equence is further divisible into three litho-units as equivalents to Gollapalli sandstone, Raghavapuram shale and Tirupati sandstone. The d epositional environment for Gollapalli sandstone is interpreted to be mainly fluvial towards NW of Tanuku horst and paralic towards SE of th e horst. The Raghavapuram shales were deposited under marine condition s. The upper part of Tirupati sandstone is of fluvial nature around Ko mmugudem area and changes gradually to paralic and to marine towards t he southeastern part of the Basin.