Abstract: Tertiary Nappe and Thrust Tectonics in Western Thailand Deducted from U/PB, RB/SR, and K/AR Age Determination

Hans Ahrendt, Bent Hansen, Klaus Wemmer

The geodynamic evolution of the central part of the southeast Asian peninsula is very complex and its interpretation is controversial. The high-grade metamorphic crystalline complexes in western Thailand and eastern Burma play an important role in the palinspastic restoration prior to the Tertiary configuration. Up to now, these crystalline units are regarded to be of Precambrian age and are considered to represent the basement of the overlying Paleozoic and Mesozoic sedimentary cover.

A multiple isotopic dating program in the basement rocks and in the very low-grade overprinted sedimentary cover points to a totally different interpretation of the structural and metamorphic evolution of the investigated area.

On the basis of the presently obtained data, a Precambrian age of the basement rocks can be excluded. These rocks suffered their last high-grade metamorphic overprint about 200 m.y. The further subsequent complex structural evolution in western Thailand culminates in a marked nappe and thrust tectonic during Cretaceous and Tertiary times.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994