摘要
中国志留系的划分与对比,始于20年代。李四光等(1924)和谢家荣等(1925)研究了三峡地区的志留系,将其全部划归下统。孙云铸(1943)从沉积旋迴角度提出了我国志留系划分的三个阶段,后又发现相应的笔石辅以佐证(孙云铸1957、洪友崇1958),将峡区的志留系分别与英国的 Llandovery,Wenlock和 Ludlow三个统对比。
Some problems concerning the Silurian correlation in South China are discussed in the present paper.The upper Lungmachi Formation and Pengjiayuan Member (i.e.Lower Lojoping Fm.) at Dazhong-ba, Yichang, W Hubei contain Monoclimacis arcuata indicating correlation of this level with the middle to upper sedgwickii biozone.The Lojoping Member (i.e.Upper Lojoping Fm.) yields Pterospathodus pennatus pennatus suggesting a Telychian age.1 he remaining succession represents generally shallowing-upward conditions with the Sliamao Fm which contains Pristiograptus variabilis and Chmacogra-ptus nebula indicating probable correlation of rhis level with the turricuatus and part of crispus biozones.However, a different opinion based on chitinuzuans indicates that the presence of Conochitina ik-laensis and C.emmastensis from the middle and upper Lojoping Member and Lower Shamao Fm.suggests a correlation with the scdgwickii brozone Kockella rannliformis(Walliser) and Pterospathodus poster it emmastensis & Barnes from the Shihniulan Fm.at Hanjiadian, Tongzi, N.Cuizhou,indicate a level close to the boundary of sedguickn and turnculaiiis biozones, i.e.Aeronian-Telychian boundary.The overlying Hanchiatien Fm.with a shallow benthic fauna containing Ancyrochitina brevicollis may be correlated with the turriculatus and partly crispus biozones.In northeast Guizhou, southeast Sichuan, northwest Hunan and southwest Hubei.there is a succession more complete than those in Dazhongba and Hanjiadian (Gc, Rong et al,1979).The alleged Lower Marine Red Beds (Rongxi Fm.) and Lower Xiushan Fm.yield Ozarkodina parahassi indicating a correlation with turriculatus to lower gricstontensis biozones.The Upper Xiushan Fm.contains a diverse shelly fauna of mostly brachiopods (such as Salopinclla, Xinanosptrifer.Nalivkina,Airypoidea, Atrypro-psis), trllobitcs (such as Coronaspis, Coronocephalus, Kailia, Rongxiclla) and nautiloids (Sichitanoceras}.The graptol il''s (Stomatograptus sinensii), conodonts (Ptcrospalhodus celloni) and chitinozoans (Angochi-lina longicoliis) occur m the Formation and suggest correlation with the upper gricstontensis and Lower crenulata biozones.This Xiushan fauna has been widely encountered in the Ningqiang Fm..N.Sichuan and S.Shaanxi, Daluzhai Fm., NF.Yunnan, Xiajiaqiao Fm , N.Jiangxi, Fentou Fm., S.Auhui and S.Jiangsu of the Yangtze Region.The highest Silurian rocks of the region, all of shallowest water origin, are the so-called Upper Marine Red Beds (Huixingshaio, Caidiwan, Xiaoxiyu, Xikeng, and Maoshan Fms.) overlying the Xiushan Fm.and its equivalents and may be correlated approximately with the latest Telychian.The later Lud-low-Pridoli rucks (the Kuanti, Miaokao and Yulungssu Fms., in ascending order) are well developed in the Qujing area, R.Yunnan where abundant brachiopods are characterized by the presence of the Mo-longia(=Protathynsina) fauna.Ozarkodina crispa(conodonts) occurs in most part of the sequence indicating a late Ludlow to early Pridoli age.The Cuifengshan Fm., known as the Devonian for a long time, may be considered to be of late Pridoli age
出处
《地层学杂志》
CSCD
北大核心
1990年第3期161-177,共17页
Journal of Stratigraphy
基金
国家自然科学基金委员会4870090项
中国科学院南京分院资助
