摘要
It was for the first time that the fossil Sm-Nd isochron method was used to date the Precambrian-Cambrian boundary. The samples were collected from the Zhongyicun Member in the Meishucun section of Jinning County,Yunnan Province, southern China. The date of 562.8±7.9Ma B.P. was obtained from four hyolithid fossil samples; another date of 562.1±5.7Ma B.P. was provided by four hyolithid fossil samples and two collophanite samples. These figures suggest that the Precambrian-Cambrian boundary reference point A, which is slightly below the Zhongyicun Member, might be about 570Ma old, and the reference point B, which is near the top of the Zhongyicun Member, could be approximately 560Ma in age. This result contributed valuable reference to precise calibration of the base of the Cambrian System in the global geological time scale.
It was for the first time that the fossil Sm-Nd isochron method was used to date the Precambrian-Cambrian boundary. The samples were collected from the Zhongyicun Member in the Meishucun section of Jinning County,Yunnan Province, southern China. The date of 562.8±7.9Ma B.P. was obtained from four hyolithid fossil samples; another date of 562.1±5.7Ma B.P. was provided by four hyolithid fossil samples and two collophanite samples. These figures suggest that the Precambrian-Cambrian boundary reference point A, which is slightly below the Zhongyicun Member, might be about 570Ma old, and the reference point B, which is near the top of the Zhongyicun Member, could be approximately 560Ma in age. This result contributed valuable reference to precise calibration of the base of the Cambrian System in the global geological time scale.
