Pb-Pb isotope dating of black shales from the Lower Cambrian Niutitang Formation, Guizhou Province, South China

作     者：CHEN Yongquan, JIANG Shaoyong*, LING Hongfei, FENG Hongzhen, YANG Jinghong and CHEN Jianhua (State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China) 

作者机构：State Key Laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China 

出 版 物：《Progress in Natural Science:Materials International》 (自然科学进展·国际材料(英文))

年 卷 期：2003年第10期

页      面：51-56页

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

基　　金：SupportedbytheNationalNaturalScienceFoundationofChina (GrantNos.40 172 0 41 40 2 2 13 0 1and 40 2 3 2 0 2 0 ) 

主　　题：Pb Pb isotope dating source of Pb black shales Niutitang Formation Yangtze Platform. 

摘      要：The Lower Cambrian black shales of the Niutitang Formation and their lateral equivalents occur widely on the Yangtze Platform, South China. In this study, we examine two sections of the Niutitang Formation in Guizhou Province. We employ a stepwise acid leaching technique to obtain Pb isotope compositions of the black shales. At the Zhongnan section, the black shales display large Pb isotope variations, with 206 Pb/ 204 Pb of 20.5396～33.5709, and 207 Pb/ 204 Pb of 15.8407～16.5782. In contrast, Pb isotope data show a relatively limited range in 206 Pb/ 204 Pb (18.2797～18.5972) and 207 Pb/ 204 Pb (15.6813～15.7159) at the Zhijin section. Data for all acid leached black shale samples from the two sections yield a Pb Pb isochron age of 531±24 Ma. This age may represent the sedimentary age of the black shales. The initial Pb isotope composition of the black shales falls near the upper crust evolution curve in a Zartman Pb Pb evolution diagram. Hence, it is likely that the Pb in the black shales may have been derived from an upper continental crustal source.