蛇绿岩的地球化学研究

Geochemistry of Ophiolites

蛇绿岩有不同的地球化学类型,但基本的是岛弧拉斑玄武岩(IAT)和洋脊玄武岩(MORB)两种。蛇绿岩的玄武岩大多数是LREE亏损型,如N-MORB和IAT。E-MORB的LREE略富集是N-MORB与OIB混合造成的。文中讨论了变质作用和水岩交换作用对蛇绿岩的改造,鉴于变质岩区蛇绿岩地球化学研究往往出现多解性,作者认为,当前至关重要的是在研究思路和方法学上要有一个突破。

There are different types of ophiolites in terms of geochemistry. Basically, the basalts from ophiolites can be grouped into two types, the island-arc tholeiites (IAT) and mid-ocean ridge basalts (MORB). Most of these basalts, for example, N-MORB and IAT, are LREE-depleted. E-MORBs are mixtures of N-MORBs and ocean island basalts (OIB), and are LREE-enriched. The impact of metamorphism and water-rock interaction on the geochemistry of ophiolites are discussed in this paper. The authors point out that a break-through in the way of study is most important at present, because the geochemistry of metamorphic ophiolites usually has multiple explanations.