Southeast Asia reconstruction with a non-rotating Cenozoic Borneo

Abstract

A reconstruction of Southeast Asia has been attempted which treats the Sunda block and the Philippine Sea Plate as (relatively) rigid blocks between 50 Ma and 15 Ma. The published reconstructions of Robert Hall (1996 version) have been utilised but modified from Borneo westwards in accordance with geological perceptions and prejudices assembled over thirty-six years of studying the region. Sunda and the Philippine Sea are treated as rigid blocks that have not undergone disruptive internal deformation. In the case of Sunda, this means that Tertiary rift basins have formed but that there has been no oceanic crust developed except in the Andaman Sea on the west and the South China Sea on the east. In this interpretation Indochina has been extruded about 700 km between 35 Ma and 15 Ma (maps are shown at five-Ma intervals, following Hall). Right-lateral movement along the Sumatra Fault! Andaman/Sagaing system is paired with left-lateral movement along the Red River Fault and its precursor, the West Baram Line. The Philippine Sea Plate has moved great distances with an overall left-lateral displacement with respect to Sunda. Smaller blocks between Sunda and the Philippine Sea Plate with less control and with strong internal deformation have been treated in this reconstruction in a manner that accommodates the movements of the major blocks.