岩浆熔体包裹体研究进展

近现代对于熔体包裹体的研究已经有50余年,但它们在反映岩浆系统特征方面的价值是直至最近10~15年间才逐渐被火山学家、岩石学家和包裹体学者所意识到。熔体包裹体的研究结果之所以难以被接受主要有以下几个因素:1)缺乏可靠的分析技术;2)熔体包裹体捕获后会发生一系列的变化;3)包裹体中熔体存在不均匀的现象;4)较高的均一温度,很难测定。但随着分析方法的改进和熔体包裹体的系统研究,学者们逐渐确定了熔体包裹体在解开岩浆系统复杂性方面的实用性,可以这么说"熔体包裹体的研究正值当年"。例如:现代的研究提供了岩浆中溶解和出溶的挥发分含量的不可否认的证据,并且从熔体包裹体中得到的气相、盐类卤水和岩浆不混溶信息证明岩浆的相分离远比从结晶相图中推论得到的要复杂得多;包裹体岩相学已详细地描绘了熔体包裹体捕获之后经历的特定变化——结晶,挥发分的扩散,气相出溶,以及泄露等。因此,如果有细致的包裹体岩相学的观察以及精确的测试分析,那么,从熔体包裹体中得到的成分数据是有用且可靠的。

Advances on melt inclusion studies

Despite nearly fifty years of modern research on silicate melt inclusions (MI), only within the past 10~15 years have volcanologists, petrologists and fluid inclusionists come to regularly accept their utility for characterizing magmatic systems. Their relatively slow acceptance was likely due to a number of factors including:1) Lack of reliable analytical techniques; 2) Concern that MI''s evolution after trapping; 3) Data sets indicative of some heterogeneous melts existed; 4) High homogenization temperatures make the data not easy to reliable. With improvements in analytical methods and careful studies of MI systematics, workers are increasingly convinced of the utility of these features to unravel the complexities of magmatic systems. Melt inclusions have "come of age" Recent studies provide compelling evidence for the compositions of dissolved and exsolved volatiles in magma reservoirs. Evidence for immiscibility of gases, hydrosaline brines and magma demonstrate that magmatic phase relations are often more complicated than can be inferred by inspection of crystalline phase. After trapping melt inclusions may undergo significant change (crystallizations), and other potential phenomenon include diffusions of volatile, vapor exsolution, and venting. With careful study we can decide MI''s composition is useful and reliable.