沉积学报
沉積學報
침적학보
ACTA SEDIMENTOLOGICA SINICA
2001年
1期
55-59
,共5页
杨威%朱忠德%刘秉理%肖传桃
楊威%硃忠德%劉秉理%肖傳桃
양위%주충덕%류병리%초전도
造礁生物群落演化模式海平面变化生物礁下奥陶统
造礁生物群落縯化模式海平麵變化生物礁下奧陶統
조초생물군락연화모식해평면변화생물초하오도통
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。
中颺子檯地下奧陶統紅花園組造礁生物群落主要有五種:藍綠藻群落(S群落)、Calathium -藍綠藻群落(C-S群落)、Batostoma-Calathium群落(B-C群落)、Archaeoscy phia-Calathium群落(A-C群落)和Batostoma-Calathium-藍綠藻群落(B-C-S群落)。群落的縯化模式有兩種: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,它們分彆對應于上下兩期生物礁。群落最大的生態差彆可能是其最適閤的水深,說明其縯化的主要動力可能是相對海平麵的變化,根據各群落適應的水深特徵,可推測紅花園建礁期為一箇海平麵下降到上升的一箇過程,相對海平麵變化的最大幅度約為15 m。生物礁內生物群落的縯化是海平麵變化的靈敏示蹤劑,可識彆5m左右的相對海平麵的變化。
중양자태지하오도통홍화완조조초생물군락주요유오충:람록조군락(S군락)、Calathium -람록조군락(C-S군락)、Batostoma-Calathium군락(B-C군락)、Archaeoscy phia-Calathium군락(A-C군락)화Batostoma-Calathium-람록조군락(B-C-S군락)。군락적연화모식유량충:①A-C군락/B-C군락→C-S군락/B-C-S군락→S군락;②S군락→C-S군락/B-C-S군락→A-C군락/B-C군락,타문분별대응우상하량기생물초。군락최대적생태차별가능시기최괄합적수심,설명기연화적주요동력가능시상대해평면적변화,근거각군락괄응적수심특정,가추측홍화완건초기위일개해평면하강도상승적일개과정,상대해평면변화적최대폭도약위15 m。생물초내생물군락적연화시해평면변화적령민시종제,가식별5m좌우적상대해평면적변화。
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).
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.
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.
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.
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.