摘要
广西桂林杨堤剖面的中至上泥盆统含有丰富的竹节石.本文对付和组、蜡烛台组和五指山组底部所含的竹节石动物群进行系统研究,认为这一竹节石动物群的面貌及其分布规律与联邦德国莱茵片岩山和民主德国图林根等地区同期的竹节石动物群较相似,以等环节石目和珠胚节石目的分子为代表,属于较深水、低能的台盆相沉积环境。 根据竹节石在剖面中的分布规律,以Homoctenus的演化系列为主,可划分出三个竹节石组合带及一个光壳类高峰带,由下至上为:1.Corna petrovi-Viriatellina fuheensis组合带;2.Homoctenus t.tenuicinctus-H.t.neylectus组合带;3.Styliolina高峰带;4.Homoctenusyangtiensis-H.u.pergracilis组合带。
The lower part of the Upper Devonian strata at Yangti near Guilin Cityof Guangxi contains abundant tentaculitid fossils, mainly representatives ofHomoctenida and Dacryoconarida, indicating a deeper-water, lower energy sedi-mentary environment. The strata containing tentaculitids are found in the Fuhe Formation, the La-zhutai Formation and the base of the Wuzhishan Formation. Lithologlcally, theFuhe Formation consists of thin-bedded, argillaceous limestone intercalated withsiliceous rocks; the Lazhutai Formation consists mainly of siliceous rocks andthe base of the Wuzhishan Formation is composed of thin-bedded limestone withbreccia (Weng et al., 1986). The tentaculites are abundant and well-preservedin many beds, especially in the Fuhe Formation, with a content in rocks amoun-ting to about 10%--20%, and possibly reaching to 30%--40%. In features and stratigraphical distribution, the tentaculites fauna at Yangtisection is similar to those of the Adorfian stage in the eastern part of RhenishSchiefergebirge and Turingia, mainly characterized by Hornoctenus, with a num-ber of styliolinids. According to the distribution of tentaculites based on theevolution of Hornoctenus, three tentaculites assemblage zones and one styliolinidacme zone can be defined in ascending order as follows: 1. Corona petrovi-Viriatelliae fuheensis assemblage zone This zone is characterized by a great number of Corona petrovi and themembers of Costulatostyliolina, Striatostyliolina and Styliolina. The lower limit ofthis zone is defined at the first occurrence of Corona petrovi. Homoctenus t. ten-uicinctus rarely occurs in the middle part of the zone. In the upper part of thezone, Viriatellina fuheensis associated with Striatostyliotina striatula in abundance.This zone formed in the lower and middle parts of the Fuhe Formation corres-ponds to the lower part of the Frasnian. 2. Homoctenes t. teneicinctus-H. t. neglectus assemblage zone This zone is characterized by the great enrichment of Homoctenus. The occur-rence of Hornoctenus tenuicinctus neglectus is defined at the lower limit of thiszone, associated with a large number of Homoctenus t. tenuicinctus,H, u. derkao-uaensis, Costulatostyliolina subconica, C. vesca, C. angusta and a few Homoctenusu. ultimus, Striatostytiolina striatula, etc. This zone is found to exist in the upperpart of the Fuhe Formation and the lower to middle parts of the LazhutaiFormation. 3. Styliolina Acme zone This zone is characterized by the appearance of styliolinids in abundance,but lacking the members of other genera. Because the fossils in siliceous rocksare not well-preserved, no information can be provided for the recognition ofspecified taxa. 4. Homoctenns yangtiensis-H. u. pergracilis assemblage zone This zone is marked by the occurrence of Homoctenus yangtiensis. H. u. per-gracilis appears in the middle part of the zone; rare members of Costulatostylio-lina, Styliolina also can be found. This zone is defined at the base of the Wuzhi-shan Formation, equivalent to the conodont, upper gigas zone and the P.linquiformis zone.
出处
《微体古生物学报》
CSCD
北大核心
1990年第1期61-75,108-110,共15页
Acta Micropalaeontologica Sinica
