藏北安多东巧地区晚侏罗世生物礁古生态学研究  

Study on Palaeoecology of Late Jurassic Reefs in Dongqiao Area in Anduo County of Northern Tibet

作　　者：肖传桃[1] 夷晓伟[1] 李梦[2] 李超[2] 

机构地区：[1]长江大学油气资源与勘探技术教育部重点实验室,湖北荆州434023 [2]成都理工大学,成都610059

出　　处：《沉积学报》2011年第4期752-760,共9页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(批准号:40972019);湖北省教育厅计划类科技项目;国家大学生创新性实验计划资助成果

摘　　要：安多东巧地区上侏罗统沙木罗组主要为一套潮坪相碎屑及台地相碳酸盐沉积,其中的特征沉积是发育有生物礁。造礁生物主要为层孔虫,其次为珊瑚,其中,层孔虫又可以分为筒状、块状和枝状3种宏观形态。在对造礁生物的个体生态学分析基础上,根据其组合特征,将生物礁划分为3个造礁群落,分别是Milleporidium—Cladocoropsis群落、Cladocoropsis—Milleporidium—Milleporella群落和Milleporidium—Actinatraea群落,其中,后两者进一步可以划分为两个亚群落。生物礁主要形成于海平面上升时期,其发育明显受海平面的升降速率与容纳空间增长速率的控制。造礁群落存在取代一种形式,这主要是由于在高海平面时期相对海平面的变化不稳定所造成,由于海平面变化过程中存在多个次一级的旋回,故导致生物礁在纵向上发育的不连续和厚度不大等特征。研究认为班公错—怒江缝合带中段洋壳俯冲时间应为中侏罗世末期或晚侏罗世沙木罗组沉积期之前,晚侏罗世沙木罗组生物礁的存在说明,研究区可能属于斑公-怒江洋壳俯冲后的残留弧后盆地中浅海大陆架的一部分。The Shamuluo Formation of Upper Jurassic in Dongqiao is mainly composed of a series of tidal flat and carbonate platform deposits and especially characterized by a lot of organic reefs.Reef-building organisms are chiefly Stromatoproids,and secondly hexacorals.Among Stromatoporoids,there are different forms such as dendritic,cylindric and massive,which reflects the second prosperous period since the late Devonian recession during geological history.The reef-building organisms mentioned above are the majority preservated at the original growth state,which all require warm,clean and normal shallow water environment with abundant light and better circulation.Through the study of individual ecology and analysis on the assemblage of reef-building organisms,three reef-building communities are recognized,namely Milleporidium-Cladocoropsis,Cladocoropsis-Milleporidium-Milleporella and Milleporidium-Actinatraea community. The analysis of sea-level changes indicate that it exists three sea-level change cycles of the reef-bearing strata in the study areas,among them,the first cycles developed in the lower section of the Shamuluo Formation,namely clastic rocks Member;whereas the second cycle developed in the lower part of the second Member of Shamuluo Formation and sea-level rising caused reef-building organisms prosperous breeding such as stromatoproids to form the first prosperous period since the late Devonian recession and shaped the first building-reefs community,namely Milleporidium-Cladocoropsis community;the third sea-level change occurs in the upper part of the second Member of Shamuluo Formation and shaped the second-third-term reefs resulting the development of the Cladocoropsis—Milleporidium—Milleporella community and Milleporidium—Actinatraea community.Replacement is the only form to the evolution of community,which is duo to the unstable of relative sea-level changes during the sea-level change peroid.It is due to the existing of the several subordinate cycles during the sea-level change peroid that the ree

关 键 词：生物礁 古生态学 海平面变化 晚侏罗世 藏北地区 

分 类 号：Q913.2[天文地球—古生物学与地层学]