中扬子台地下奥陶统红花园组造礁生物群落主要有五种：蓝绿藻群落(S群落)、Calathium -蓝绿藻群落(C-S群落)、Batostoma-Calathium群落(B-C群落)、Archaeoscy phia-Calathium群落(A-C群落)和Batostoma-Calathium-蓝绿藻群落(B-C-S群落)。群落的演化模式有两种：①A-C群落／B-C群落→C-S群落／B-C-S群落→S群落；②S群落→C-S群落／B-C-S群落→A-C群落／B-C群落，它们分别对应于上下两期生物礁。群落最大的生态差别可能是其最适合的水深，说明其演化的主要动力可能是相对海平面的变化，根据各群落适应的水深特征，可推测红花园建礁期为一个海平面下降到上升的一个过程，相对海平面变化的最大幅度约为15 m。生物礁内生物群落的演化是海平面变化的灵敏示踪剂，可识别5m左右的相对海平面的变化。%A lot of reefs have been discovered in Honghuayuan Formation of Lower Ordovician in the Central Yangtze Platform. Their rock comparisons contain two types. One is baffle stone. Another is binding stone. Their reef-building organisms cont ain five types.They are bluegreen alga (containing blue bacterium and Girvanel la) , Calathium, Batostoma, Pulchrilamina, and Archaeoscyphia as representation of rock sponge. They composite five types of reef-building organism community. Is bluegreen alga community (S-community), Calathium-bluegreen algaec ommunity (C-S community), Archaeoscyphia-Calathium community (A-C communi ty), Batostoma-Calathium community (B-C community), Batostoma-Calathium -bluegreen algae community (B-C-S community).rn Ecological environment of each of reef-building organism community and the most lithofacies assemblage of host rock may indicate characteristics of eac h c ommunity,which includes water body environment and the most depth range suitable . Each community can adapt normal shallow sea of warm, clean, rich sunshine and oxygen, and cyclic better. But the most suitable depth may be different. S-com munityre presents shallow water and small energy. C-S community and B-C-S community ma y be 5～10 m and medium-large water energy. B-C community and A-C community may be 10～20 m and large water energy.rn Organism belt has been discovered in reefs of thickness over 5m in the study area. Organism belt is a result of organism community evolution,and is the most in tuitive evidence of organism community evolution. Organism belt within reefs fr om bottom to up may indicate two models of community evolution. The trend of their evolution is ①A-C community or B-C community→C-S community or B-C-S community→S-community, ②S-community→C-S community or B-C-S community→A -C community or B-C community. This is an entire course of community from grow thtodeath. Organism richness of community interior has also been changed with time. rn Because the most suitable water depth of each community is different, the force of organism community evolution may be sea level change. According to the most suitable water depth of reef-building organic community, detailed change of sea level can be diagnosed in reef-building term.rn Relative sea level change is from a falling course of 20～10 m→10～5 m→5 m to a rising of 5 m →10～5 m→20～10 m. The largest change magnitude of sea level is about 15 m. This is similar to the former. So, according to the r eef-building organic community evolution can quantitatively study small mag nitude sea level change.
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