Abstract: Tectonics of Cenozoic Sedimentary Basins in Southeast Asia
Claude Rangin
In southeast Asia, marginal basins, floored with oceanic crust, and shelf basins, developed on the continental basement of Sundaland, were created during two main extensional events in the Cenozoic. First, an Eocene-early Oligocene northeast-southwest-directed
extensional event prevailed, controlling spreading in the Celebes Sea
, rifting in the South China
Sea
, and shelf basin development, the latter mainly in Borneo and the Java
Sea
. A late Oligocene-early Miocene
north
-south-directed extension period was responsible for spreading in the South China
Sea
and the development of large shelf basins in Malaysia, western Indonesia, and Vietnam. This major change within the regional tectonic extension
field
in southeast Asia is also marked by a widespread middle Oligocene unconformity. We suggest it is directly linked to changes of trench-pull forces along the Eurasian plate boundary at 30 Ma, the time for incipient docking of the Philippine
Sea
plate along the eastern margin of Eurasia. We conclude that during the Eocene-early Oligocene, opening
of both the Celebes
Sea
and the coeval shelf basins took place with mismatch basins forced along northwest-southeast strike-slip shear zones as a result of Indochina extrusion and trench pull along the free boundary into the east. To the contrary, after docking of the Philippine
Sea
plate, trench-pull forces were only present along the Sunda trench, and the South China
Sea
as well as the shelf basins of western Sundaland were induced by
north
-south extension.
AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994