The Western Ailaoshan Volcanic Belts and their SE Asia connection: A new tectonic model for the Eastern Indochina Block

The Western Ailaoshan (WAL) Volcanic Belts mark the western boundary of the South China-Indochina Suture Zone along the Ailaoshan Fold Belt Geochronological and geochemical evidence suggests that the WAL Volcanic Belts vary in ages and origins, and includes (1) L. Carboniferous-earliest M.-Permian (ca. 300-270 Ma) incipient backarc basin magmatism; (2) M. Permian (ca. 265 Ma) island arc/mature backarc basin magmatism; (3) early L Permian (ca. 260-255 Ma) WAL-Indochina arc-continent collision and the associated syn-collisional granitic magmatism, as well as subsequent (4) E. Triassic (ca. 250-245 Ma) post-collisional magmatism. Regional geological comparison indicates that the post-L Carboniferous WAL tectonic evolution was closely related to the Eastern Indochina Block. We present a new G-Plate geodynamic evolution model for the Ailaoshan Fold Belt and its surrounding South China-Indochina region, based on new and published U-Pb zircon ages, together with whole rock and Pb-isotope geochemical data. (C) 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.