Tectonic properties and post-reformation in Late Triassic, Ordos Basin

Based on the analysis of over 60 outcrops and over 300 important exploratory wells,combined with previous studies,applying the principles of plate tectonics and geodynamics,it was discussed in this paper the tectonic environment,basin property and late-stage reformation of the Ordos Basin during the Late Triassic.Conclusions were made as followed.1) During the Late Triassic,the main part of the basin was a cratonic depre-ssion while the southern(southwestern) margin was a foreland basin and the northwestern margin was a rift basin.This setup might be related to the special geological boundary conditions of the basin and the special force way during the Late Triassic.2) Prototype basin experienced 4 stages of various late-stage reformations,which caused basin area reducing by about 300 000 km².3) Based on the distribution of residual source rocks,except for the inner part of the basin and the foot of the thrust belt in the western margin,the Liupanshan Basin to the west and the Weihe Basin to the south of the Ordos Basin are also worth exploring in the future.