Petrography, geochemistry and U-Pb detrital zircon dating of the clastic Phu Khat Formation in the Nakhon Thai region, Thailand: implications for provenance and geotectonic setting

摘要

The clastic Phu Khat Formation is the topmost unit of the red bed sequence (mainly Khorat Group and overlying salt formation) in the Indochina Block (Heggemann, 1994).It is well exposed in the Nakhon Thai region, which is located between two tectonic terranes, the composite Nan-Uttaradit Suture and Sukhothai Zone to the west and the Loei-Phetchabun Fold Belt and Indochina Block to the east.The formation was interpreted to have been derived from both western and eastern thrust fault blocks in the Latest Cretaceous-Early Tertiary (Heggemann, 1994).However, this interpretation is principally based on surface mapping without detailed study.Therefore, the purpose of this study was to determine the provenance and tectonic setting of the Phu Khat Formation using petrography and whole-rock geochemistry integrated with U-Pb detrital zircon dating.