Indian Plate Collision in Pakistan and Myanmar and Its Impact on Hydrocarbon Prospectivity

Bannert, Dietrich ¹; Khan, Moin R.²
(1) Consultant, Isernhagen, Germany. (2) Pakistan Petroleum Ltd, Karachi, Pakistan.

India is continuously subducted under the Himalayas and the direct contact is now concealed by Lesser Himalayan units. In the west, however, west of Indus River the Indian Plate docked with the Afghan Block, an already accreted part of the Southern Eurasian Plate assemblage, in an oblique mode along the northern extension of the Owen-Fracture Zone, manifested in the modern Chaman Fault System. East of it, an extremely stretched part of the Makran-Khojak-Katawaz Zone, composed of flysch and molasse sediments was reduced to merely 20 km across the strike. Strike-slip faults east of it segmented the Indian Plate in due course providing a further northward drift of the Indian Plate’s main body. The reduction of drift velocity in the west resulted in an anticlockwise rotation of the Indian Plate. Indian Plate sediments contain favourable source and reservoir rocks yielding significant oil and gas accumulations both in structural and stratigraphic traps. Continuous exploration efforts are expected to result in more discoveries.

In the east in Myanmar, flysch deposition commenced during Paleogene, which continued through Lower Eocene and is followed by Oligo-Miocene molasse sediments. Only during Middle Miocene uplift of the Rakhine Yoma separated the Gulf of Bengal from the Inner-Burma-Tertiary-Basin. Shelf sediments of the Indian Plate comparable to Pakistan are missing here, as in Myanmar the geological setting is quite different. Oil and gas accumulations are restricted to the Innerburman Tertiary Basin and its southward offshore extension, which contains deep marine flyschoid sediments followed by shallow water limestone, marl and sandstones of mostly Neogene age. Towards the Bay of Bengal a fore-arc basin develops, characterized by gas driven mud-volcanoes and of oil deposits.

The off-shore areas of Pakistan, especially offshore Makran, are identical in several ways to the settings of Myanmar’s offshore oil and gas fields. Mud volcanoes, gas-hydrates and heavy input of fine-grained sediments from Indus River and Nal River provide encouraging conditions for hydrocarbon prospecting.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.