Genetic types of Permian organic reefs and prediction of hidden reefs in the eastern Sichuan-western Hubei area

The genetic classification of organic reefs (prograded reefs, collateral reefs and retrograded reefs) is established from the angle of the control of the relative sea level rise and fall on the growth and development of reefs and the attributes of Permian reefs in the eastern Sichuan western Hubei area are described on that basis. The authors propose the view of co existence of prograded reef and retrograded reefs in the area and predict hidden reefs according to the directions of progradation and retrogradation of reefs. They suggest that the horizon at the southeastern side of the Jiantianba reef cluster in western Hubei is equivalent to the hidden reef belt in the third member of the Changxing Formation, and that to the west of the Huaying eastern Sichuan reef forming belt there might exist a hidden reef belt which is stratigraphically equivalent to the top of the third member of the Changxing Formation.