Cenozoic Tectonic Accretion of Indian Volcanic Ridges along the Sunda Continental Margin in the Andaman Sea Myanmar and southern Myanmar
The N-S hyper-oblique active convergence zone between India and Sunda lithospheric plates extends along the complex Myanmar and Andaman mobile belts, establishing the tectonic link between the Sumatra subduction zone and the India/Eurasia collision. Along the slightly oblique Sumatra Subduction zone, the Indian volcanic ridges of the Australian lithospheric plate are subducted and partially incorporated into the accretionary prism. In the Andaman Sea, the Andaman-Nicobar Ridge (ANR) and the Alcock-Sewell Ridge (ASR) are docking along the Sunda continental margin since the mid Miocene. This tectonic process is particularly well documented in the northern Andaman Sea along the ANR and ASR natural northward extensions, the Cocos-Preparis ridges and the Yadana platform where fast growth and demise of carbonate platforms are coeval with these volcanic ridges accretion, These drilled ridges compared with the 90°E volcanic Ridge extending offshore in the Bay of Bengal and studied during the DSDP-ODP international drilling program reveal the same exotic origin, a LIP volcanic type basement representative of hot spot volcanic ridges originally developed in the Indian ocean and Gondwana. At larger scale in the Andaman Sea, the westward progression of these volcanic ridges east to west accretion process offers a new model for progressive carbonate platform grows and demise during the Cenozoic. The Cenozoic tectonic development of the Myanmar mobile belt is more complex, but is marked since 10 Ma, by the 90°E Ridge oblique subduction along the southern Arakan Range. No evident classical criteria of subduction was observed along this continental margin in surface and sub-surface data, such as development of sedimentary accretionary wedge or piggy back basins, but instead giant submarine mass flows and avalanches, as well as by fast uplift of this Myanmar coastal belt and the tectonic inversion of the Central Myanmar Basins suggesting presence of a large asperity below western Myanmar, the subducted 90°E Ridge. This model of progressive volcanic ridge tectonic accretion to a continental margin offers new opportunities for new plays discoveries in the Andaman Sea.
AAPG Datapages/Search and Discovery Article #90336 ©2018 AAPG Asia Pacific Region, The 4th AAPG/EAGE/MGS Myanmar Oil and Gas Conference, Myanmar: A Global Oil and Gas Hotspot: Unleashing the Petroleum Systems Potential, Yangon, Myanmar, November 13-15, 2018