Bulletin of the Geological Society of Malaysia, Volume 20, August 1986, pp. 179 – 199
1All-Union Institute of Geology of Foreign Countries, Dimitrova, 7 Moscow, 109180, U.S.S.R.
2Department of Geology, University of Malaya, 59100 Kuala Lumpur, Malaysia
Abstract: Continental Southeast Asia is dominated by Precambrian continental blocks overlain by Late Proterozoic to Paleozoic platform successions, representing Atlantic-type rifted miogeoclinal margins. All the blocks appear to have rifted and drifted from the Australian part of Gondwanaland. The timing and extent of their separation is analysed by the distribution of Permian Cathaysian Gigantopteris and Gondwana Glossopteris floras, assisted by dated tectono-structural units, paleoclimate indicators, and good quality paleomagnetic data.
Between the blocks lie narrow intensely folded Phanerozoic mobile belts, which developed on the oceanic crust of the Paleotethys ocean, characterized by pelagic-turbidite flysch sequences which shallowed as the oceans narrowed. The narrowing was effected by subduction resulting in island arcs within the oceans, and cordilleran volcano-plutonic arcs along the block margins. Extinction of the basins resulted in collision zones containing S-type granites and suture zones containing dismembered ophiolites. Post-consolidation plate readjustments resulted in wrench and rift faulting in several places while convergence continued elsewhere.
The tectonic analysis has been carried out by recognizing tectonic elements (structural-formational units) for selected Phanerozoic time frame. We also present a Phanerozoic sequence of palinspatic reconstructions for the rifting and drifting of the blocks from northern Australia. These are consistent with the known ages and distributions of the tectono-structural units and the good quality paleomagnetic data. We also present an analysis of the first-order relationship between the distribution of mineral deposits and the igneous events which resulted from tectonic reactions between the Precambrian blocks and the mobile belts.