寒武系全球排碧阶及芙蓉统底界的标准层型剖面和点位

国际地球科学联合会2003年2月批准了由中美科学家组成的联合研究小组的建立全球排碧阶和芙蓉统底界标准层型剖面和点位的提案,以我国地名命名的“排碧阶”和“芙蓉统”两个全球年代地层单位及其底界的全球层型正式确立,这是寒武系内所确立的第一个“金钉子”。排碧阶和芙蓉统分别是寒武系的首个全球阶级标准单位和首个全球统级标准单位。排碧阶和芙蓉统的共同底界的全球层型剖面位于湖南花垣排碧附近的四新村,底界划在该剖面花桥组底界之上369.06m,与球接子三叶虫Glyptagnostus retuculatus的首现一致。芙蓉统的建立,取代了长期使用的非正式年代地层单位“上寒武统”。

GLOBAL STANDARD STRATOTYPE-SECTION AND POINT FOR THE PAIBIAN STAGE AND FURONGIAN SERIES OF CAMBRIAN SYSTEM

The International Union of Geological Sciences(IUGS)has recently ratified the Global Stan- dard-stratotype Section and Point(GSSP)for the base of Paibian Stage and Furongian Series proposed by a Sino-U.S team including Peng shan-chi from Nanjing Institute of Geology and Palaeontology (NIGPAS),L.E.Babcock from the Ohio State University,Columbus,Ohio(OSU),R.A.Robison from the Kansas University,Lawrence,Kansas,Lin Huanling(NIGPAS),M.N.Rees from the Nevada University,Las Vegas,Nevada,and M.R.Saltzman(OSU).This is the first intra-Cambrian GSSP for the Cambrian System,and the Paibian and the Furongian are known respectively as the first formal Stage and the first formal Series within Cambrian.The stratotype section of Paibian Stage and Furongian Series is situated near Paibi,a small town in Huayuan County,northwestern Hunan Province,South China.Its geographic coordinates are latitude 2°23.37.37′N,longitude 109°31.54′E of Greenwich,England.The Paibi section is approximately 35 km west of the city of jishou along the north side of the Jishou-Huayuan highway(Chinese National Highway 319),and approximately 35km south of Huayuan.The base of the Paibian Stage(also the base of the Furongian),is defined at 369.06m above the base of the Huaqiao For- mation In the Paibi section,corresponding to the First Appearance Datum(FAD)of cosmopolitan agnos- toid trilobite Glyptagnostus reticulatus(Angelin),which is within a continuous evolutionarg sequence of Glyptagnostus species.