Abstract:

Three geonlorphictheories i.e.dynamic equilibrium,piedmonttreppen as well as the geomorphic cycle are briefly discussed in the paper.It is obvious to know that accordant summits and stepped landforms are of various genesis indeed,and planation surfaces should be the elevated peneplain and multiple planation surfaces excluding to faulting must be responsible for multiple geomorphic cycles.It is not easy to identify the planation surfaces from the accordant summits with other origins by general methods.However,using a fuzzy model of planation surfaces,combing with three standards of planation surfaces identification,the planation surfaces in north Guangdong are recognized.They are: the North Guangdong Surface (1010-1350m above sea level (ASL),the Yanashan Surface (610-780m ASL),the Renhua Surface (410-460m ASl) and the Yingde Surface (300-350m ASL) respectively,the antic characteristics of which are also presented.The strata records in the basins both in enclosed and nearby areas as well as in the continental shelf suggest that the ages of the four surfaces are late Cretaceous to early Oligocenc,middle Oligocene to early Miocene,middle Miocene to late Pliocene and Quaternary respectively.The researches on the planation surfaces in the region also manifest that the fault-block movemant including their uplifting,subsiding and tilting is the basic feature and that the height of the North Guangdong Surface can represent the maximum elevation in neotectonic period in northern Guangdong region (estimated to exceed 1300m).

Key words: Planation surfaces, North Guangdong