Geochemical and geochronological record of the Andaman Ophiolite, SE Asia: From back-arc to forearc during subduction polarity reversal?

Ophiolites are widely studied to unravel how new subduction zones form. They may contain crustal and mantle rocks that formed during juvenile stages of intra-oceanic subduction, modifying the pre-existing oceanic lithosphere within which started, in a magmatic arc upon maturation. Previous geochemical work on Cretaceous Andaman Ophiolite its metamorphic sole, located forearc Sunda zone south-east Asia, has revealed signatures difficult reconcile single tectonic setting but rather record different longer evolution. A recent kinematic reconstruction proposed have initiation former back-arc basin, when (Woyla) collided with Sundaland continent. Here, we evaluate whether such scenario provide feasible context explain enigmatic preserved Ophiolite. To this end, new, review existing as well geochronological constraints formation rocks, evolution portion. We identify mafic cogenetic plagiogranites consistent arc, whereas other sole protoliths, characteristics indicative origin. Three two previous zircon U/Pb ages give 99–93 Ma age range, also an inherited ~105 age. This latter coincides Ar/Ar cooling plagioclase xenocryst from Barren Island volcanics east Andaman. The ophiolites straightforwardly explained regional history: (1) original basin Woyla arc; (2) Subduction SSZ ophiolite occurred around or slightly before 105 Ma; (3) was followed by magmatism between 99 93