Isotopic dating of the Chengjiang Fauna-bearing horizon in Central Yunnan Province, China

Abstract

Twenty black shale samples, which are free from the influence of weathering, were collected from the Chengjiang Fauna-bearing horizon, central Yunnan Province, yielding a Pb-Pb isochron age of 534±60 Ma. Although this age is younger than both the Rb-Sr isochron age and ^sup 40^Ar-^sup 39^Ar age, it should represent the lower isotopic age limit of the Chengjiang Fauna.[PUBLICATION ABSTRACT]