SEQUENCE STRATIGRAPHY OF MIDDLE EOCENE TST IN BROACH-JAMBUSAR BLOCK, CAMBAY BASIN, INDIA

Abstract

The Cambay Basin (fig.1) is a narrow elongated intracratonic rift graben situated in north western part of Indian Peninsula. The Basin consist of several intra basinal uplifted blocks,Saurashtra Craton on the west, Aravalli swell on the northeast and Deccan Craton to the southeast. It extends from north of Sanchor to the south in Cambay Gulf and ultimately open into the Arabian Sea. The Basin has Deccan Trap volcanic rocks as technical basement over which 7 kms (+) thick Cenozoic sediments were deposited. The Basin is divided into two sub-basins namely North Cambay and South Cambay based on their lithostratigraphy and sedimentation pattern. The present study is confined to Broach-Jambusar Block of South Cambay Basin. In this Block, reservoirs within Hazad Member are the major producers of Hydrocarbons. The Hazad Member of Middle Eocene is a TST part of “Middle Eocene to Late Eocene II order sequence”. The Hazad Member, resting over the coeval Younger Cambay Shale, belongs to this 2nd order TST and is bounded by the Y-Marker at the base (unconformity) and by the Kanwa Shale at the top (marking the maximum flooding surface). However, such a TST is characterized by several short term fining-up and coarsening-up successions, within an overall fining up trend. Thus, identification of these high frequency cycles and corresponding sequence stratigraphic surfaces is felt necessary to bring out the changes in sedimentation pattern in the Hazad Member within a high resolution sequence stratigraphic framework.