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鄂尔多斯盆地西南缘的陕西陇县李家坡晚奥陶世背锅山组生物礁为典型的台地边缘礁,包括层孔虫礁、珊瑚礁、钙藻礁等几种类型,主要为层孔虫礁。经过系统古生物学研究,鉴定出层孔虫有5个属,分别为Ecclimadictyon(蜂巢层孔虫)、Clathrodictyon(网格层孔虫)、Tuvaechis(图瓦层孔虫)、Rosenella(罗森层孔虫)、Labechiella(小拉贝希层孔虫)等;珊瑚有6个属,分别为Tetradium(四分珊瑚),Hemiagetolitella(拟半阿盖特珊瑚),Plasmoporella(似网膜珊瑚),Eofletcheria(始弗莱契珊瑚),Catenipora(镣珊瑚),Reuschia(劳氏珊瑚);钙藻以Vermiporella(蠕孔藻)和Solenopora(管孔藻)为主。礁发育早期以层状层孔虫包卷砂屑、单体珊瑚、管状海绵、块状钙藻等形态为主要特征,礁发育中后期以块状和球状的层孔虫以及大型的床板珊瑚形成格架为主要特征。礁体发育过程中居礁生物都很丰富,有三叶虫、腕足类、介形类、大棘皮类和丛状的蓝细菌等。通过与塔中台地以及扬子台地的晚奥陶世台缘礁对比,发现造礁生物的属种和礁岩类型均有相似之处,说明中国晚奥陶世生物礁的分布具有等时性。
The reefs of the late Ordovician back-pot group in Lijiapo, Long County, Shaanxi Province in the southwestern margin of Ordos Basin are typical platform margin reefs, including lamina reef, coral reef and algae reef. After systematic paleontological research, there are 5 genera of larvae identified as Ecclimadictyon, Clathrodictyon, Tuvaechis, Rosenella, Labechiella, etc. There are 6 genera in the corals: Tetradium, Hemiagetolitella, Plasmoporella, Eofletcheria Crifetus, Cuspidora, Reuschia, and Vermiporella and Solenopora. In the early stages of reef development, the lamellae were mainly composed of sand-lamellae, single corals, tubular sponges and massive calcareous algae. In the middle and late stage of reef development, massive and spherical laminatrines and large bed corals formed Grid as the main feature. During reef development, reef organisms are very rich, trilobites, brachiopods, ostracods, large echinoderms and plexiform cyanobacteria. By comparison with the Late Ordovician margin of the platform in the Tazhong platform and the Yangtze platform, it is found that there are similarities between the genus and reef types of the reef-forming organisms, indicating that the distribution of the Late Ordovician reefs in China is isochronous.