Palaeomagnetic research in Southeast Asia: progress, problem and prospects

Abstract

Southeast Asia is a complex assembly of allochthonous continental terranes now far removed from their sites of origin together with island arcs, accretionary complexes and small ocean basins (Fig. 1). The boundaries between these terranes are marked by major fault zones or by sutures recognised by the presence of ophiolites, melanges and accretionary complexes. Stratigraphical, sedimentological, palaeobiogeo-graphical and palaeomagnetic data suggest that most, and probably all, of the Southeast Asian continental terranes were derived directly or indirectly from Gondwana. These terranes were assembled between the Late Palaeozoic and Cenozoic, but the precise times of rifting from Gondwana and timings of amalgamation and accretion are still contentious. Cenozoic modification of the region involves major strike-slip faulting, rotations and spatial displacements of crustal blocks, and the development of marginal basins. Palaeomagnetic data are vital for constraining the movements of crustal blocks in this region and ongoing systematic regional palaeomagnetic research is critical for an improved understanding of the geological evolution of Southeast Asia.