金伯利岩定年方法综述

Review of Kimberlite Dating Methods

本文根据近四十年具有代表性的金伯利岩定年研究和所发表的年龄数据,在前人工作基础上总结出5种应用广泛的金伯利岩定年方法,并从定年效果、矿物结构和结晶习性等角度对比梳理了不同方法的误差来源和局限性。结果显示,锆石U-Pb年龄结果具有较好的精度和较高的稳定性,但需要确保锆石样品为地幔来源;云母Rb-Sr法和K-Ar或^(40)Ar/^(39)Ar法相对其他方法难以把控准确性和稳定性,而钙钛矿由于具有明确的来源,其U-Pb年龄非常精准可靠。因此对金伯利岩定年,以钙钛矿的U-Pb法为好。

In this paper, we have summarized 5 methods which are widely applied for the kimberlite dating based on the representative studies and published ages of the kimberlite in the past 40 years, and have compared the error sources and limitations of different methods from the perspectives of dating effect, mineral structure and crystallization habit. The results show that zircon U-Pb dating results have good accuracy and stability, but it is necessary to be ensured that the zircon samples must be from the mantle. Compared with other methods, the accuracy and stability of the Rb-Sr and K-Ar or^(40)Ar/^(39)Ar dating methods of micas are difficult to be controlled. However, the U-Pb ages of perovskites from kimberlites have high precision and reliability because of the clear sources of perovskites. The perovskite U-Pb dating method should be firstly considered for dating kimberlites in the future.