Biostratigraphy, Paleoenvironments and Cycles of Sea Level Change in the Subsurface Paleogene Succession of Akholjuni Area, Cambay-Tarapur Block, Cambay Basin, India
Jagmohan Singh and Kamal K. Nayak
GEOLOGY, ONGC, Vadodara, India
Biostratigraphic studies of Paleogene succession of Akholjuni area in the south west part of Tarapur-Cambay depression has led to recognition of five third order cycles. Oil in commercial quantities can possibly be discovered from the Middle Eocene and Miocene Basal Sands. Six biostratigraphic markers have been recognised and used to establish east-west and north-south biostratigraphic correlation. The subsurface section in Akholjuni area of Cambay basin has revealed presence of Deccan Trap basement with overlying approx. 2000 m thick pile of sediments. The Deccan Traps are overlain by more than 100m thick sediments of Olpad Formation, which consists of mainly claystone derivatives of Deccan Trap. The first marine transgression might have reached this area during Early Eocene. This is marked on the basis of full-grown species of N. burdigalensis. It is inferred that the Middle Eocene sediments were deposited under shallow marine/fluctuating environment. The major transgression took place during the latest Eocene having revealed the maximum flooding surface.
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