Negative carbon isotopic excursion on the Lower/Middle Cambrian boundary of Kaili Formation, Taijiang County, Guizhou Province, China: Implications for mass extinction and stratigraphic division and correlation  

作　　者：杨瑞东 朱立军 王世杰 

机构地区：[1]State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China [2]Guizhou University of Technology, Guiyang 550003, China

出　　处：《Science China Earth Sciences》2003年第9期872-881,共10页中国科学（地球科学英文版）

基　　金：the National Natural Science Foundation of China(Grant No.40062001);the Governor Foundation of Guizhou Province;the Post-doctoral Foundation of Guizhou University of Technology and the Excellent Youth Scientists and Technicians Foundation of Guizhou Province,and a special program by MSTC(Grant No.2002CCC02600).

摘　　要：The stratigraphic division and correlation of the Lower/Middle Cambrian boundary is a global problem that has not yet been perfectly solved up to now. That is because there existed two global biogeographic regions during the period from Early Cambrian to Middle Cambrian. Although much work has been done from the angle of paleontology and great achievements have been acquired in this aspect, no biological assemblage has yet been established for global stratigraphic correlations due to the coexistence of the two global biogeographic regions —— the Atlantic biogeographic region and the Indian-Pacific biogeographic region during the Early-Middle Cambrian. So, to develop and establish other approaches to the stratigraphic division and correlation of the Lower/Middle Cambrian on a global scale is a possible way to solve the puzzling problem. This work systematically studied acritarch fossils from the Early-Middle Cambrian Kaili Formation at Taijiang County, Guizhou Province. The Lower/Middle Cambrian boundary was divided in terms of acritarch fossil assemblage. The divided boundary is generally consistent with what was divided by trilobite and can be correlated with the Lower/Middle Cambrian boundaries divided by acritarch assemblage in Siberia and Europe. On this basis, the Lower/Middle Cambrian boundary is divided in terms of an obvious carbon isotopic excursion on a global scale during the transitional period from Early Cambrian to Middle Cambrian boundaries in Siberia and North America. The method for the stratigraphic division and correlation of the Lower/Middle Cambrian boundary in terms of carbon isotopic oscillations is helpful to solving the global problem on the division and correlation of the Lower/Middle Cambrian boundary. It is also evidenced that the extinction of a lot of trilobites at the end of Early Cambrian is closely related with this event of carbon isotopic excursion.The stratigraphic division and correlation of the Lower/Middle Cambrian boundary is a global problem that has not yet been perfectly solved up to now. That is because there existed two global biogeographic regions during the period from Early Cambrian to Middle Cambrian. Although much work has been done from the angle of paleontology and great achievements have been acquired in this aspect, no biological assemblage has yet been established for global stratigraphic correlations due to the coexistence of the two global biogeographic regions—the Atlantic biogeographic region and the Indian-Pacific biogeographic region during the Early-Middle Cambrian. So, to develop and establish other approaches to the stratigraphic division and correlation of the Lower/Middle Cambrian on a global scale is a possible way to solve the puzzling problem. This work systematically studied acritarch fossils from the Early-Middle Cambrian Kaili Formation at Taijiang County, Guizhou Province. The Lower/Middle Cambrian boundary was divided in terms of acritarch fossil assemblage. The divided boundary is generally consistent with what was divided by trilobite and can be correlated with the Lower/Middle Cambrian boundaries divided by acritarch assemblage in Siberia and Europe. On this basis, the Lower/Middle Cambrian boundary is divided in terms of an obvious carbon isotopic excursion on a global scale during the transitional period from Early Cambrian to Middle Cambrian boundaries in Siberia and North America. The method for the stratigraphic division and correlation of the Lower/Middle Cambrian boundary in terms of carbon isotopic oscillations is helpful to solving the global problem on the division and correlation of the Lower/Middle Cambrian boundary. It is also evidenced that the extinction of a lot of trilobites at the end of Early Cambrian is closely related with this event of carbon isotopic excursion.

关 键 词：NEGATIVE CARBON ISOTOPIC excursion  extinction  Lower/Middle CAMBRIAN boundary  Guizhou Province. 

分 类 号：P597[天文地球—地球化学]