震旦系陡山沱组的底与待建的末前寒武系的下界  

THE BASE OF THE SINIAN DOUSHANTUO FORMATION AND THE LOWER BOUNDARY OF THE TERMINAL PROTEROZOIC SYSTEM

作　　者：张启锐[1] 

机构地区：[1]中国科学院地质研究所

出　　处：《地质科学》1994年第1期96-99,共4页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金

摘　　要：震旦系陡山沱组的底与待建的末前寒武系的下界张启锐（中国科学院地质研究所北京１０００２９）关键词末前寒武系，下界层型，陡山沱组底，海进面，浓缩层臼１９ＢＳ年末前寒武系工作组成立以来，末前寒武系的建系工作正式开展起来．鉴于寒武纪ｊ前寒就纪的界线层型已经确...Since the establishment of the Working Group on Terminal Proterozoic System.criteria for locating of stratotypes of the system and the lower boundary have beenunder consideration.Two suggestions on the lower boundary were concentrated,thefirst is to set the boundary at the top of Varanger,probably corresponding to theNantuo Formation in South China,whereas the second is to look for the boundaryabove the top of Varanger and below the Ediacaran,which may be coeval with thenewly discovered Miaohe Fauna from the Doushantuo Formation in the Yangtze Gorges area.From the sequence-stratigraphic view,the author considers that the first suggestionwill not meet the requirements of stratotype for a boundary. Data from South Chinaproved that the top of Nantuo Formation resulted from a transgression caused by climatic change from iceage to fair weather.Evidence from the,base of Doushantuo Formation shows that it was a ravinement surface,which appears to be a time transgressive surface.It seems that the second suggestion is more acceptable,though it implies a neweffective criterion to be erected. From the geologic setting in South China,the boundary has to be located within the range of Dosbantuo formation.One possible candidate interval could be somewhere in the condensed section,mainly composed oforganic-rich black shale,which is fossiliferous and well suitable for chemostratigraphic study.

关 键 词：地层 震旦纪 陡山沱组 底部 浓缩层 

分 类 号：P534.31[天文地球—古生物学与地层学]