Structural variation along highway 12, Amphoe Lom Sak, Changwat Phetchabun

Abstract

Highway 12 along km 327 to 347 cuts through the western margin of Phetchabun Basin, Amphoe Lom Sak, Changwat Phetchabun. The good quality outcrops shows the variation of structures were formed by Triassic to present tectonic activities. The objectives of this study are to create geological map and construct the structural evolutionary model via field investigation, geomorphology interpretation by DEM and satellite image and Digital Outcrop Model. The results found that overturned of Phu Kradung Formation that related to steep reverse faults are on the west of the study area. The middle part are dominated by normal faults associate with right-lateral strikeslip faults in Nam Phong and Lower Huai Hin Lat Formation while Upper Huai Hin Lat Formation only exposes in the eastern part of the road with normal faults. Furthermore, the structural evolutionary model can be divided into 3 stages as follows: 1) Early Triassic: the Permian carbonate rocks were deformed on the west of Indochina block 2) Late Cretaceous – Late Eocene (N-S compression): Khorat Group completely deposited then strike-slip stress with right-lateral movement caused positive and negative flower structures that create the pop-up or uplifting of the western margin of Phetchabun Basin 3) Oligocene – Present: The tectonic zone of strike-slip was inactive but dominate by erosion.