Triassic subduction initiation and Cretaceous forced collision along the West Myanmar Block

Subduction initiation was demonstrated at the western margin of the West Myanmar (Burma) Block, specifically in relation to the Thanbaya Formation (a Triassic unit), suggesting that the post-Permian (249 Ma) Cimmerian Superterrane had drifted away from Gondwana. The West Myanmar Block was revealed as an oceanic plateau through intra-oceanic subduction (ocean-ocean subduction), situated at the passive margin of the Sibumasu Block, based on provenance studies of the Thanbaya Formation and the occurrence of Triassic Cr spinel in the Thanbaya Formation and the Sibumasu Block. The Cretaceous forced collision was indicated by the Mawgyi volcanics in the Popa-Monywa-Wuntho magmatic arc, as the Mawgyi N-MORB-like rocks, characterised by flat REE patterns and depleted in REEs (Rare Earth Elements), HSFEs (High Field Strength Elements ) (except Th), and TiO2, are geochemically very similar to the Izu-Bonin-Mariana proto-arc basalts. The new field evidence constructs an east-west geological cross-section through the Indo-Myanmar Ranges and Mount Popa on the different tectonic domains. Paleogeography of the Sibumasu Block was revealed from the Variscan orogens in Europe to Gondwana anticlockwise rotation, together with the Cimmerian Superterrane, to the opening of the Neo-Tethys Ocean. • Forced Subduction during Triassic Subduction Initiation Forced subduction conditions during the Triassic subduction initiation event. • Oceanic Crust in the West Myanmar and West Sumatra Blocks The West Myanmar Block and the West Sumatra Block were oceanic crust, located west of the Sibumasu Block in the Cimmerian Superterrane during the Triassic. • Triassic Ophiolite Formation and Oceanic Rifting in the Neotethys Formation of Triassic ophiolite, associated with oceanic rifting in the Neotethys, and the obduction of Jurassic High-Pressure/Low-Temperature (HT/LT) metamorphic ophiolites. • Cretaceous Forced Subduction-Related Accretion Timing of forced subduction-related open wedge accretion in the Cretaceous, in relation to the pop-up anticlinal structure of Mount Victoria Land (Kanpetlet Schist) and the Woyla nappe in western Sumatra.