Abstract:

The Upper Permian bioherms of Guizhou are composed of the remains ofvarious kinds of sponges and siphonoconchs which are haphazardly distribu-ted in micrite matrix.Organisms are usually surrounded by lime muds whichform agate-like stripes or bands but bear no relation to algae.Lime mudsare all chemical precipitates deposited during diagenesis.They form calcitesof different morphology(microcrystalline,fibrous,comb-like and poikilitic),which do not merely occur as crusts enclosing organisms but also fill theirregular voids.The sponges,attacked constantly by violent waves,are continuously bo-ring and destroying the substrate of carbonate rocks and at the same timeproviding various peculiar pores for sponges to live in,for sedimentationand cementation,and thereby a unique framework is formed.Any of theseprocesses may follow earlier ones,thus forming bioherms or edgewise organicmounds distinct from general frame work reefs.In this paper,the Late Permian of Guizhou is divided into the fluvial,delta-plain,subaqueous delta,inner-continental shelf(carbonates),outer-continental shelf(tuffaceous clastic and siliceous sediments)facies.Biohermsare only distributed at the contact zone between the inner and outer conti-nental shelf facies;along this zone,bioherms can be traced discontinuously.The reef zone within the territory of Guizhou generally stretches in a NEE direction,only the section between Ceheng and Wangmo being locally com-plicated.The section occurs as an appendix bulging northwards,thus cre-ating a false impression that there are“two rows”in local places.The distribution of the reef zone is controlled by sedimentary environmentsand processes rather than by anticlines.Wherever the reef zone runs by,its traces should be left whether on anticlines or on synclines.Its exposureon anticlines is only a superficial phenomenon.