高温地质过程钙稳定同位素的分馏及应用

Stable Ca Isotope Fractionation and Application in High-Temperature Geological Processes

钙元素广布于地球各圈层,由于其具有流体活动性,因此在许多地质过程中都扮演着重要的角色。随着多接收电感耦合等离子体质谱仪(MC-ICP-MS)以及热电离质谱仪(TIMS)同位素分析技术的进步,近十年来钙同位素高温地球化学示踪技术发展迅速,取得了一系列研究成果,包括:厘定了陨石、月球、火星和地球的钙同位素组成;制约了主要富钙矿物间的平衡分馏系数;探讨了多种高温过程中钙同位素的分馏机理及控制因素。目前的研究显示,稳定钙同位素地质示踪剂有望广泛应用于研究行星物质起源、地幔演化、壳幔物质循环等重要地球科学问题。本文对这些成果进行了归纳总结。

Calcium is an important alkali earth element that is distributed widely in the Earth. Because of its fluid mobility, Ca plays an important role in a variety of geological processes. With the advancement of the multi-collector inductively coupled plasma-mass spectrometer(MC-ICP-MS) and thermal ionization mass spectrometer(TIMS), the high-temperature Ca isotope geochemical tracing techniques have been developed rapidly and a series of research achievements have been obtained over the last decade. The Ca isotope compositions of chondrites, Moon, Mars, and major reservoirs within the Earth have been constrained. The equilibrium Ca isotope fractionation factors among major Ca-bearing minerals have been determined. The mechanisms and controlling factors of Ca isotope fractionation in high-temperature geological processes have been preliminarily investigated. Recent studies show that the stable Ca isotope geological tracer is expected to be widely applied for studying a variety of first-order questions in the solid Earth science such as the planetary material origination, mantle evolution, and crust-mantle material recycling. In this paper, we have summarized these research achievements.