副矿物微量元素地球化学特征在成岩成矿作用研究中的应用

Trace element geochemistry of accessory minerals and its applications in petrogenesis and metallogenesis

文中较系统地介绍了国外近年来基于矿物合成和激光原位定量分析测试技术发展的副矿物,重点是锆石,其次是金红石、石榴石、榍石及磷灰石等微量元素地球化学特征在成岩成矿温度、氧逸度、源区物质等方面的研究成果。这些成果是在不同温度、压力及体系成分条件下合成的矿物,结合自然界岩石相关副矿物成分分析,获得了副矿物中微量元素含量与形成温度、压力、氧逸度等之间存在严格线性关系,建立了定量计算公式,并给出了这些温度计、氧逸度等计算公式的适用范围。根据广泛用于同位素定年的锆石受变质和热液蚀变而出现复杂年龄譜,文中还介绍了用锆石微量和稀土元素地球化学特点,结合近年来在这方面的研究成果,探讨了Th/U比值识别锆石成因存在的问题,介绍了稀土元素组成识别锆石成因的原理和应用。

This is a review on the accessory mineral geochemistry. Rapid successful developments of accessory mineral geothermometer have been achieved because of the evident progress in high precision in-situ analyses and mineral synthetic techniques. Accessory mineral thermometer,especially zircon,and next rutile,garnet,and sphene are introduced systematically in this paper. The combined experimental and natural mineral analyses define that the contents of trace elements between accessory mineral and associated minerals varies in linear dependence upon temperature and oxygen fugacity,and the equations for different accessory minerals thermometers are given by many researchers. The Th/U ratios,used as an indictor of zircon genesis,must be treated with caution. REE distribution patterns in metamorphosed or hydrothermal zircons and apatites are discussed and their implications for petrogenesis are introduced.