熔体包裹体挥发分应用的研究进展

挥发分(例如H2O、CO2、F、Cl和S)是地幔的重要组成部分,虽然它们在地幔中的含量很低,但是在地幔熔融和熔体演化、地幔不均一、地幔流变学、地幔地震特性和电导率等研究方面具有重要作用。对矿物熔体包裹体和玻璃挥发分的研究已经成为当前的研究热点。其中,熔体包裹体研究凭借其独特的优势成为研究地幔和岩浆挥发分组成的重要手段。熔体包裹体直接捕获了矿物形成时岩浆中的成分,且由于寄主矿物的存在使得熔体包裹体能够保持独立演化而不受外界环境影响,因此能够较为完整地保存岩浆中的挥发分信息。同时,研究熔体包裹体中的挥发分是恢复岩浆喷发前挥发分含量最直接的途径。如果通过现代分析方法(如扫描电镜、电子探针和离子探针等)对熔体包裹体进行详细的岩相学观察以及对后期可能影响熔体包裹体原始挥发组分的作用(地壳混染、岩浆去气、扩散和水化作用)进行评估,并结合实验研究熔体包裹体被捕获后发生的变化而对数据进行矫正,那熔体包裹体对研究岩浆体系中的挥发分将大有可为。基于此,本文系统介绍了熔体包裹体挥发分研究的现状及主要研究内容,主要包括熔体包裹体挥发分的测试方法、挥发分在岩浆中的溶解度、判断挥发分数据可靠性和挥发分研究的经典应用等4个方面。

A review on the application of volatiles in melt inclusions

Volatiles such as H₂O, CO₂, F, Cl and S are important components of the mantle. They play vital roles in the seismic characteristics and conductivity of the mantle, mantle inhomogeneity, mantle rheology, mantle melting and melt evolution despite their low content in the mantle. Research on volatiles of melt inclusions in minerals and glass has become a hotspot. Furthermore, the melt inclusion is the best medium to study the composition of the mantle and magma volatiles by virtue of their unique advantages. The melt inclusion directly captures the components in the magma during the formation of the mineral. Due to the presence of the host mineral, the melt inclusions can maintain independent evolution without being affected by the external environment, so that the volatile information on the magma can be well preserved. At the same time, investigating the volatiles of melt inclusions is the direct way to obtain the volatile content of magma prior to the magma eruption, so lots of studies of melt inclusions have been conducted to restore the volatile content before magma eruption. If the modern analytical methods, such as scanning electron microscopy, electron microprobes and ion probes, are used to perform detailed petrographic observations on melt inclusions combined with experimental studies to determine the changes after the capture of the melt inclusions, the melt inclusions would play an important role in the study of the volatile content of the magma system and source processes. Thus, this paper systematically introduces several important problems on studying the volatiles in melt inclusions, including the analytical methods, solubility of volatiles in magma, the reliability of volatiles data and the application of volatiles.