Tectonic Control from Sedimentation in Upper Assam Foreland, Assam-Arakan Basin

Pradeep Goswami¹ and Pulin C. Goswami^2
1KG-Basin, Oil and Natural Gas Corporation Limited, Rajahmundry, India
²Oil & Natural Gas Corporation Ltd, Ankleshwar, India

Alluvium covered Upper Assam plains and Dhansiri Valley constitute the foreland part of Assam-Arakan basin. Marine to fluviatile clastic sediments from Mesozoic to Tertiary dominate its stratigraphy. The Upper Assam foreland is considered to have remained tectonically stable during the evolution of Assam-Arakan basin. Exploratory activities for hydrocarbon have generated a significant amount of geo-scientific data which has contributed towards better understanding of the overall geology and evolution history of the foreland basin. The interpretation of densely spaced seismic grids and well data throws light on the role of tectonics on differential sedimentation, facies distribution and subsequent preservation of sediments in this foreland basin. Syndepositional faulting during extensional basin forming stage from Cretaceous to Mio-Pliocene time provided the space necessary for accumulation of its stratigraphic succession. A complex interplay between climate, structural growth due to extensional tectonics and relative variations in sediment input had controlled differential sedimentation as well as development of non-depositional hiatuses in different structural blocks/segments of the foreland basin. Syndepositional inversion of pre-existing faults during basin modifying stage had marked effect on differential sedimentation and development of non-depositional hiatuses in the Tertiary succession.

The results will help to resolve long-standing controversies concerning its stratigraphic framework, facies relationship and unconformities encountered in different parts of the foreland. The understanding of the role of tectonics on sedimentation in this foreland basin will be useful for exploration of strati-structural traps.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery