Mid-Cretaceous inversion in the Northern Khorat Plateau of Lao PDR and Thailand

Abstract

Abstract Evidence is presented from the study area for the occurrence of a regional compressive tectonic event in the mid-Cretaceous (Aptian-Cenomanian). This is tentatively attributed to the effects of a distant continent-continent collision to the west. Pre-existing structural trends were reactivated parallel to palaeo-continental sutures to the northeast (Song Ma and Song Da) and west (Nan). The event interrupted the latest Jurassic to earliest Palaeocene subsidence and continental sedimentation of the Khorat Plateau Basin. The primary effects are shown by seismic data to be regional tilting, compressive folding, reverse faulting and inversion of the basin subsidence pattern. The data do not support the current view that such structuring was initiated during the Tertiary. However they do show that there was some reactivation of mid-Cretaceous structures during regional uplift in the Tertiary. This revision of timing of structuring suggests the hydrocarbon potential of the area may be greater than previously anticipated.