华南寒武系年代地层系统的修订及相关问题

将早先提出的华南寒武系4统9阶的年代地层系统,修订成4统10阶,除王村阶的底界略高于全球鼓山阶(Drumian Stage)的底界外,其余界线都与目前的全球4统10阶的年代地层界线一致。新系统采纳了在我国华南建立的全球芙蓉统、排碧阶和古丈阶,在原桃源阶的上部另建"牛车河阶"。原王村阶和桃源阶的时限因这一修订有所缩减。全球鼓山阶的底界与台江阶上部的Ptychagnostus atavus带底界可以精确对比。滇东统包含晋宁阶和梅树村阶(狭义)两个年代地层单位,晋宁阶的底界采用全球寒武系的底界,梅树村阶的底界采用罗惠麟等1994年正式修订后的定义,即位于梅树村剖面的"B"点。梅树村阶的原始定义仅指梅树村剖面的磷块岩层(即现今的中谊村段),它的底界高于现在的以Tricophycus pedum首现定义的全球寒武系底界。

REVISlON ON CAMBRIAN CHRONOSTRATIGRAPHY OF SOUTH CHINA AND RELATED REMARKS

Revision was made on the earlier proposed chronostratigraphy of South China.The revised chronostratigraphy includes 4 series and 10 stages with all boundaries,except for the base of the Wangcunian Stage,correspond to those proposed or defined within global subdivision of the Cambrian System.The base of Wangcunian is slightly younger than the base of global Drumian Stage,which coincides with the FAD of Ptychagnostus atavus and correlates precisely to the base of Ptychagnostus atavus Zone in the uppermost part of Taijiangian Stage in South China.Furongian Series,Paibian Stage and Guzhangian Stage,which are ratified as global standard chronostratigraphical units by IUGS,are adopted by the revised Cambrian framework and a new stage,the Niuchehean Stage,is erected as the youngest Cambrian stage of South China.Duration of the Wangcunian and Taoyuanian stages is reduced after revision.The Diandongian Series of South China consists of two stages,the Jinningian Stage below and the overlying Meishucunian Stage(sensu stricto),of which the base of Jinningian Stage uses the base of ratified global Cambrian System,and the base of Meishucunian Stage is placed at the "B Point" in the Meishucun section,at which the stage is defined formally by Luo Hui-lin et al.in 1994.The original definition of the Meishucunian Stage is introduced from the Meishucun Formation that is composed of phosphorite beds(i.e.the Zhongyicun Member) with its base remarkably younger than the current base of global Cambrian System,which is defined by FAD of Tricophycus pedum at Fortune Head,Newfoundland,Canada.