How rigid are the lithospheric plates? Fault and shear rotations in southeast Asia

Evidence is presented to show that significant fault movement occurred during the Tertiary in continental southeast Asia, within an area generally regarded as part of the Eurasia plate. Three separate but linked rotations can be recognized: an Indochina subplates wrench rotation, a Sunda shear rotation, and the rotation of the Malay Peninsula and the Sunda Platform in toto by movements along the Ranong and Semangko faults. Spherical geometry constraints on rotation allow a pre-Oligocene map reconstruction of southeast Asia to be made which offers explanations for the patterns of Quaternary faulting, of Tertiary sedimentation, and of pre-Tertiary geosynclinal and mineralization belts.