Structural characteristics in Ayutthaya basin

Abstract

The Ayutthaya Basin is a N-S trending Cenozoic basin located in Lower Central Plain Thailand. The basin overlies on Mae Ping fault zone in NNW-SSE trend. 2D seismic sections and well data are included to illustrate a structural and stratigraphic variation in the basin. Surface map, isopach map, tectono-stratigraphy and structural evolutionary model are presented in this study. Ayutthaya basin is characterized by half-graben geometry which is eastward tilted. The major faults are west dipping normal fault with N-S oriented. The evolution of Ayutthaya basin can be divided into 4 phases. The first phase commences with extensional rifting in which the basin was developed during the Late Oligocene to Middle Miocene period. Subsequently, the extensional stress ended and subsidence phase had increased. After that, the stress regime had changed to the NNW compression which episodically resulted in strike-slip reactivation and basin inversion phase. Finally, the overall stress has been stopped in Pliocene. Basins were subsided without significant tilting or rotating.