Deformation history and U-Pb zircon geochronology of the high grade metamorphic rocks within the Klaeng fault zone, eastern Thailand

作者：Kanjanapayont Pitsanupong^*; Kieduppatum Piyanuch; Kloetzli Urs; Kloetzli Eva; Charusiri Punya

来源：Journal of Asian Earth Sciences, 2013, 77: 224-233.

DOI：10.1016/j.jseaes.2013.08.027

• Deformation
• U-Pb zircon geochronology
• Klaeng fault zone
• Thailand

In eastern Thailand the Klaeng fault zone includes a high-grade metamorphic rock assemblage, named Nong Yai Gneiss, which extends about 30 km in a NW-SE direction along the fault zone. The rocks of this brittle-fault strand consist of amphibolite to granulite grade gneissic rocks. Structural analysis indicates that the rocks in this area experienced three distinct episodes of deformation (D-1-D-3). The first (D-1) formed large-scale NW-SE-trending isoclinal folds (F-1) that were reworked by small-scale tight to open folds (F-2) during the second deformation (D-2). D-1 and D-2 resulted from NE-SW shortening during the Triassic Indosinian orogeny before being cross-cut by leucogranites. D-1 and D-2 fabrics were then reworked by D-3 sinistral shearing, including shear planes (S-3) and mineral stretching lineations (L-3). LA-MC-ICP-MS U-Pb zircon dating suggested that the leucogranite intrusion and the magmatic crystallization took place at 78.6+/-0.7 Ma followed by a second crystallization at 67 1 to 72.1+/-0.6 Ma. Both crystallizations occurred in the Late Cretaceous and, it is suggested, were tectonically influenced by SE Asian region effects of the West Burma and Shan-Thai/Sibumasu collision or development of an Andean-type margin. The sinistral ductile movement of D-3 was coeval with the peak metamorphism that occurred in the Eocene during the early phases of the India-Asia collision.

• 出版日期2013-11-15