钛同位素地球化学综述  

A review of titanium isotope geochemistry

作　　者：赵新苗[1,2] 唐索寒[3,4] 李津[3,4] 朱祥坤[3,4] 王辉[1,5] 李志汉 张宏福 ZHAO Xinmiao;TANG Suohan;LI Jin;ZHU Xiangkun;WANG Hui;LI Zhihan;ZHANG Hongfu(Institute of Geology and Geophysics,Chinese Academy of Sciences,State Key Laboratory of Lithospheric Evolution,Beijing 100029,China;Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China;Key Laboratory of Deep-Earth Dynamics,Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Key Laboratory of Isotope Geology,Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;University of Chinese Academy of Sciences,Beijing 100049,China;Department of Geology,Northwest University,State Key Laboratory of Continental Dynamics,Xi'an 710069,China)

机构地区：[1]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国地质科学院地质研究所自然资源部深地动力学重点实验室,北京100037 [4]中国地质科学院地质研究所自然资源部同位素地质重点实验室,北京100037 [5]中国科学院大学,北京100049 [6]西北大学地质学系大陆动力学国家重点实验室,陕西西安710069

出　　处：《地学前缘》2020年第3期68-77,共10页Earth Science Frontiers

基　　金：国家自然科学基金项目(41973015,41673021,41473005,41688103,41430104,41873027)。

摘　　要：随着分析技术的进步,非传统稳定同位素体系在地球化学、天体化学和生物地球化学等研究领域的应用日益广泛。钛(Ti)是一个非常重要的过渡族金属元素,在地球和其他类地球行星中广泛存在。但是由于Ti是一种难熔的、流体不活动性元素,高温地质过程中Ti同位素分馏很小。人们对Ti同位素体系的地球化学应用的关注相对其他非传统稳定同位非常有限。而近年来,随着化学纯化方案的优化以及双稀释剂方法的改进和仪器质谱性能的提高,Ti同位素组成的高精度测试已经能够实现。天然样品中Ti同位素组成的变化随之得以发现,使得学者们能够利用这一新的稳定同位素体系来解决与高温和低温地球化学相关的问题。很快Ti同位素体系地球化学研究成为当前国际地质学界的前沿研究课题和新的发展方向之一。本文首先在简要介绍Ti元素和Ti同位素体地球化学性质的基础上,介绍了Ti元素化学分离和Ti同位素分析方法。随后笔者总结了已有的不同类型球粒陨石和地球样品的质量相关Ti同位素组成研究结果,对硅酸盐地球的Ti同位素组成做了初步评估。前人对高温地质样品的Ti同位素组成研究初步探明Ti同位素在岩浆演化过程,例如部分熔融和结晶分异等重要地质过程中的分馏行为。笔者在此基础上探讨了结晶分异过程中引起Ti同位素分馏的主要控制因素,指出Ti同位素是潜在的研究岩浆演化过程的新工具。最后笔者探讨了Ti同位素地球化学未来的发展方向,以加速我国在Ti同位素地球化学方面的应用研究。Advances in analytical techniques lead to increasing application of non-traditional stable isotope in the investigation of high-temperature processes,such as magmatic differentiation,core formation,and early solar nebula evaporation and condensation.Although titanium(Ti)is a very important transition metal element occurring widely on Earth and other Earth-like planets,Ti stable isotope has received little attention to date.This is because Ti is relatively insoluble in sub-critical aqueous fluids and is highly refractory,i.e.,resistant to later modification or resetting by metamorphism or alteration.Its isotopic variations have seldom been measured.Recent advances in double spike technique and the development of multi-collector inductively coupled plasma(MC-ICPMS)make it possible to acquire Ti isotopes with high precision.As a result,significant fractionation of Ti stable isotope has been found in natural samples.The large fractionation has important implications for the measurement and application of Ti isotopes,with great potential in tracing various geological processes.In this review,we summarized the recent advances,important applications and future directions of Ti isotope geochemistry.We start with a brief summary on nomenclatures and analytical methods,followed by Ti isotopic compositions of chondrites and Bulk Silicate Earth(BSE),then with a summary on the magnitude and mechanisms of Ti isotopic fractionation during magmatic differentiation at high temperatures.It seems that Ti isotopes can serve as high-fidelity tracers of magmatic evolution and genesis of ancient igneous rocks and Earth’s crust.Finally we highlight future work needed to advance the research and applications of Ti isotope geochemistry.

关 键 词：钛 钛同位素 同位素质量分馏 地球化学示踪 

分 类 号：P597.2[天文地球—地球化学]