Dating of zircon LA-MC-ICP-MS U-Pb in metabasalt of zhaertai group, Inner Mongolia, China

Abstract

Present study consists on the sedimentation age of the Mesoproterozoic Zhaertai Group exposed along the northern margin of the North China Craton using zircon ages. The results showed that the Th/U of zircon varied greatly, from 0.20 to 1.77. Also, the mean ages of the two Concordia Groups of ²⁰⁶Pb/²³⁸U were 2503.1 ± 2.6Ma (n = 20, MSWD = 1.6), and 1688.0 ± 11Ma (n = 8, MSWD = 1.5), respectively. The age of 2503.1 ± 2.6Ma indicated that the zircon originated from the basement rock, in the underlying late Archean to the early Paleoproterozoic era. The group age of approximately 1688.0 ± 11Ma indicated that the Zhaertai Group underwent a magma accident at approximately 1.7 Ga, which may had some connection with North China’s continental cracking event at approximately1850 to 1650Ma. That is to say, the North China Craton’s stretch tectonic regime led to non-orogenic magma incidents in the Zhaertai Group at the northern margin of the North China Craton before 1688.0 ± 11Ma. Metabasalt zircons of approximately 1688.0 ± 11Ma also revealed that the sedimentary age of the Zhaertai Group may be approximately 1.7 Ga, and the Zhaertai, Baiyun Obo, and Huade Groups should be considered to be contemporary sedimentary.