Tectonic Disposition of Back-Arc Andaman Basin and Its Hydrocarbon Potential

Arora, Varnika ¹; Misra, Kiran S.¹
(1) Petroleum and Earth Sciences, University of Petroleum and Energy Studies, Dehradun, India.

This study synthesizes the geological setting and tectonic evolution of Andaman basin and its bearing on hydrocarbon exploration. This crescent shaped basin is bordered in the west by the Andaman-Nicobar chain of islands and by Burma, Thailand and Malaysia land masses in the east.

Geologically it is located in back-arc setting of prominent Indonesian island arc. The Andaman chain of islands represent an island arc system which continues as a subduction zone in Sumatra-Java region of east Indies. From tectonic point of view, this region is highly complex,as it is located in the proximity of subduction zone, Oceanic 90 Degree East ridge and rift system. This subduction zone is believed to exist on the western side of Andaman-Nicobar chain of islands, where volcanism is recorded intermittently. In southern continuation, however, rampant volcanism prevails along this zone.

Furthermore, finding of uninterrupted Tertiary sedimentary sequence comprising pre, syn and post rift sedimentary rocks indicates that the area has been under extensional tectonics, since the beginning of Cenozoic. This is also supported by geological details obtained from seismic profiles presence of extensive coral reef complexes and drill hole data. Therefore, this study does not support the theory of compressional tectonics related to subduction zone in this area.

Back arc basins are gaining lot of importance as they are found to have fairly good potential for hydrocarbons. It has emerged from the present study that petroliferous Irrawaddy rift system continues from land area into the Andaman Sea through its delta region in the middle. This area prognosticates for higher detailed exploration because source rock, reservoir rock with antecedent tectonic continues in this area. Discovery of three major pools such as Kuala Langsa, Arun and North Sumatra Offshore within Miocene Coral reef complexes, suggests that the entire basin needs to be relooked and explored.

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