广西志留系的基本特征

广西志留系在桂南、桂东南一带发育完善,下、中、上三统均有出露,由一套厚达7000m的半深海、深海复理石、类复理石碎屑岩组成,富含笔石化石。随着区调工作的深入开展,钦州、玉林一带相继发现早泥盆世含笔石地层,并与上志留统整合接触;岑溪糯洞亦发现含曲靖鱼的下泥盆统与上志留统整合接触。该区不但是我国华南唯一海相志留—泥盆系连续出露的地区,也是我国研究中上志留统以及志留系与泥盆系界线比较理想的地

BASIC CHARACTERISTICS OF THE SILURIAN OF GUANGXI

The Silurian System of Guangxi is completely developed in southern and southeastern Guangxi,the lower,middle and upper series being all present. It is composed of a sequence of bathyal and abyssal flysch and flyschoid clastic rocks,more than 7,000 m in thickness,containing an abundance of graptolites. In Qinzhou and Yulin the Upper Silurian displays conformable contacts with the Early Devonian Monograptus uniformis （graptolite）-bearing strata,while in the vicinity of Cenxi the Lower Devonian containing Qujinolepis sp. （fish fossil）has conformable contacts with the Upper Silurian containing Protathyris sp. （brachiopod）. This is of important significance in the study of the distri- bution of the Caledonian-Variscan geosyncline in southern Guangxi,Silurian- Devonian boundary and nature of the Guangxi movement. 19 graptolite zones have been established in the Silurian System of Guang xi; from below upwards they are the Glyptograptus persculptus,Akidograp- tus acuminatus,Pristiograptus cyphus,Demirastrites tsiangulatus,D. convolu- tus,Monograptus sedgwickii,Spirograptus turriculatus,Streptograptus crispus,Monoclimacis griestoniensis,Stomatograptus grandis,Cyrtograptus angustus,C. murchisoni,Monograptus riccartonensis,Pristiograptus dubius,P. vulgaris,Pristiograptus nilssoni,P. tumescens,P. ultimus and P. transgrediens zones. Studies indicate that the Silurian terrigenous clastic rocks in Guangxi belong to turbidites and that there exist Early Silurian abyssal turbidites in Beiliu county,Guangxi.