Abstract: Luxiang fault depression is a first-order tectonic unit of Yitong Basin. The strata in the fault depression feature in new era, multiple source, and rapid deposition. There exist many problems in conventional stratigraphic division and correlation and traditional sequence division. Based on the clear understanding of two third-order sequences of Wanchang Formation in southern Luxiang fault depression, analyzing the attributes of maximum entropy spectrum, fourth-order sequences are identified accurately. The method has many advantages such as no limit to sampling length and higher resolution to the spectra. It may be used to accurately identify the location of maximum flooding surface. Furthermore, it provides a more intuitive understanding of the characteristics of system tract and cycling within the third-order sequence.

Key words: Yitong Basin, Luxiang fault depression, attribute of maximum entropy spectrum, Milankovitch cycles, sequence stratigraphy