Tectonic framework and Phanerozoic evolution of Sundaland

Abstract

Sundaland comprises a heterogeneous collage of continental blocks derived from the India–Australian margin of eastern Gondwana and assembled by the closure of multiple Tethyan and back-arc ocean basins now represented by suture zones. The continental core of Sundaland comprises a western Sibumasu block and an eastern Indochina–East Malaya block with an island arc terrane, the Sukhothai Island Arc System, comprising the Linchang, Sukhothai and Chanthaburi blocks sandwiched between. This island arc formed on the margin of Indochina–East Malaya, and then separated by back-arc spreading in the Permian. The Jinghong, Nan–Uttaradit and Sra Kaeo Sutures represent this closed back-arc basin. The Palaeo-Tethys is represented to the west by the Changning–Menglian, Chiang Mai/Inthanon and Bentong–Raub Suture Zones. The West Sumatra block, and possibly the West Burma block, rifted and separated from Gondwana, along with Indochina and East Malaya in the Devonian and were accreted to the Sundaland core in the Triassic. West Burma is now considered to be probably Cathaysian in nature and similar to West Sumatra, from which it was separated by opening of the Andaman Sea basin. South West Borneo and/or East Java-West Sulawesi are now tentatively identified as the missing "Argoland" which must have separated from NW Australia in the Jurassic and these were accreted to SE Sundaland in the Cretaceous. Revised palaeogeographic reconstructions illustrating the tectonic and palaeogeographic evolution of Sundaland and adjacent regions are presented.