In the study of ancient reefs, especially Permian reef, how can determine the precise time-framework? such as determine which Stage in the Gadalupian series of middle Permian; or detect the timing framework of different parts in a reef (fore-reef. reef-core and back-reef). In addition, for the Permian reef, massive standard fossils are lost, such as fusulinid and conodonts. So I need to get some suggestions.