摘要
地球形成最早10亿年的岩石记录稀缺,严重阻碍了地质学家对地球早期地壳起源的认识.短寿命放射性衰变的^(146)Sm-^(142)Nd同位素体系,由于其较短的半衰期(103 Ma),可以示踪地球早期的不相容元素分异过程,是制约早期地壳起源机制的重要手段.当前已有地球化学证据显示早期地球可能有多次地幔不相容元素亏损事件,而导致早期地球地幔亏损的原因很可能是冥古宙大规模原始地壳的形成.大规模的冥古宙原始地壳不仅是地球上多数现存最古老的始太古代岩浆岩的前身,也为新太古代大陆的形成提供了重要的物质来源.首先简述^(146)Sm-^(142)Nd体系定年和示踪的基本原理,并介绍142Nd同位素异常的分析方法.在此基础上,系统总结了全球有始太古代岩石出露的地块的142Nd同位素异常特征,探讨早期地球地壳的起源模式.
The understanding of the origin of Earth’s earliest crust is incomplete due to the limited rock record in the first billion-year of Earth’s history.The short-lived isotope system,^(146)Sm-^(142)Nd,taking advantage of its short half-life of 103 Ma,is especially effective in tracing the chemical differentiation of incompatible elements during the Hadean and thus constraining the origin of the first crust on Earth.Studies show that multiple mantle depletion events may have occurred on the early Earth that were likely caused by the formation of massive proto-crust.The massive proto-crust is not only the likely progenitor of the oldest preserved igneous rocks on Earth,but also has served as the nuclei for the formation of Neoarchean continent.Here in this review article,the isotopic systematics and the analytical methods of^(146)Sm-^(142)Nd were reviewed,and the current models for the formation of Earth’s earliest crust were discussed based on a compilation of 142Nd isotopic anomaly data of ancient samples from global Eoarchean terranes.
作者
王达
Wang Da(Research Center for Planetary Science,School of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2024年第11期3879-3889,共11页
Earth Science
