The Bentong-Raub Suture Zone

It is proposed that the Bentong-Raub Suture Zone represents a segment of th e main Devonian to Middle Triassic Palaeo-Tethys ocean, and forms the bound ary between the Gondwana-derived Sibumasu and Indochina terranes. Palaeo-Te thyan oceanic ribbon-bedded cherts preserved in the suture zone range in ag e from Middle Devonian to Middle Permian, and melange includes chert and li mestone clasts that range in age from Lower Carboniferous to Lower Permian. This indicates that the Palaeo-Tethys opened in the Devonian, when Indochi na and other Chinese blocks separated from Gondwana, and closed in the Late Triassic (Peninsular Malaysia segment). The suture zone is the result of n orthwards subduction of the Palaeo-Tethys ocean beneath Indochina in the La te Palaeozoic and the Triassic collision of the Sibumasu terrane with, and the underthrusting of, Indochina. Tectonostratigraphic, palaeobiogeographic and palaeomagnetic data indicate that the Sibumasu Terrane separated from Gondwana in the late Sakmarian, and then drifted rapidly northwards during the Permian-Triassic, During the Permian subduction phase, the East Malaya volcano-plutonic are, with I-Type granitoids and intermediate to acidic vol canism, was developed on the margin of Indochina. The main structural disco ntinuity in Peninsular Malaysia occurs between Palaeozoic and Triassic rock s, and orogenic deformation appears to have been initiated in the Upper Per mian to Lower Triassic, when Sibumasu began to collide with Indochina. Duri ng the Early to Middle Triassic, A-Type subduction and crustal thickening g enerated the Main Range syn- to post-orogenic granites, which were emplaced in the Late Triassic-Early Jurassic. A foredeep basin developed on the dep ressed margin of Sibumasu in front of the uplifted accretionary complex in which the Semanggol "Formation" rocks accumulated. The suture zone is cover ed by a latest Triassic, Jurassic and Cretaceous, mainly continental, red b ed overlap sequence. (C) 2000 Elsevier Science Ltd. All rights reserved.