PAN style="FONT-SIZE: 14pt; mso-font-kerning: 0pt" lang=EN-US>Based on an analysis of rock component characteristics, sedimentary facies characteristics, development regularity of seismites and tuff in Interval 8～Interval 6 oil layers of Yanchang Formation, the authors put forward a method for investigating the early structural evolution and the process of sedimentary response. Researches indicate that Qinling was uplifted at the early depositional stage of Interval 8 whereas Liupanshan was uplifted at the late depositional stage of Interval 7. The depositional period from Interval 8 to Interval 6 of Yanchang Formation is regarded as the early formation period of Ordos Basin in the Mesozoic. The tectofacies of Interval 8 is relatively stable, and there exist no seismites and carbonate debris in the sandstone, only with the development of shallow water delta in the study area.
