Regional tectonics, structure and evolution of the Andaman–Nicobar Islands from ophiolite formation and obduction to collision and back-arc spreading
Published:January 01, 2017
Chris K. Morley, Mike Searle, 2017. "Regional tectonics, structure and evolution of the Andaman–Nicobar Islands from ophiolite formation and obduction to collision and back-arc spreading", The Andaman–Nicobar Accretionary Ridge: Geology, Tectonics and Hazards, P. C. Bandopadhyay, A. Carter
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A wide range of tectonic models exist for the Cretaceous–Cenozoic development of the Sumatra–Andaman–Myanmar region, reflecting outstanding regional issues including: (1) suture zone correlation between Tibet and Myanmar; (2) understanding ophiolitic fragment emplacement; (3) timing of ophiolite emplacement; (4) tectonic setting of ophiolite formation; (5) post-emplacement ophiolite history; (6) number, distribution and accretion timing of different tectonic continental blocks in western SE Asia; (7) how the Andaman–Sumatra subduction zone developed during the Cenozoic, and location and timing of inactive, v. obliquely subducting segments; and (8) considerable variations in regional plate tectonic reconstructions (e.g. latitude of Lhasa Block at the time of collision, amount and direction of block rotation within SE Asia). Following reviews of these issues we propose a relatively simple model whose characteristics are continuity of a single continental mass between Myanmar and Sumatra during the Cenozoic, early Cenozoic ophiolite emplacement as imbricate slices within an accretionary complex and no emplacement of a major overthrusting oceanic slab. Subsequent collisional deformation further dismembered the ophiolites. Approximately 30° clockwise rotation of SE Asia occurred following Asia–India collision, accompanied by transition from a paired Andean-type magmatic belt to regional oblique-slip and strike-slip tectonics. During the Neogene the Andaman sea region became dominantly transtensional, while Myanmar in the Late Neogene became transpressional.
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The Andaman–Nicobar Accretionary Ridge: Geology, Tectonics and Hazards
Rocks exposed across the hundreds of islands that belong to the 800 km long Andaman–Nicobar archipelago provide a condensed window into the active subduction zone that separates the India–Australia plate from the over-riding Burma–Sunda plate. Despite a strategic and seismically active location the Andaman-Nicobar ridge has seen comparatively little research. This Memoir provides the first detailed and comprehensive account of geological mapping and research across the island chain and adjacent ocean basins. Chapters examine models of Cenozoic rifting of the Andaman Sea and the regional tectonic and seismogenic framework. A detailed critical review of the Andaman–Nicobar stratigraphy, supported by new data, includes arc volcanism and a description of Barren Island, India’s only active volcano. Seismic history and hazards and the impacts of the 2004 earthquake and tsunami are also described. The volume ends with an examination of the region’s natural resources and hydrocarbon prospects.