Geochemical tracers of mantle processes
Geochemical tracers of mantle processes
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地幔过程的地球化学示踪剂
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
W. White
中科院分区：
文献类型：
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作者：
W. White
地幔能直接取样的情况很少。因此，地球化学家在很大程度上依赖于幔源岩浆来研究地幔的组成和演化。只有那些不受岩浆作用影响的成分特征才能作为地幔作用的示踪剂。这些包括放射性同位素比值，如He、Sr、Hf和Os的比值，稳定同位素比值，以及高度不相容元素或类似不相容元素的比值，如Ba/Nb或Pb/Ce。“不相容”一词是指元素对熔体的偏好超过地幔矿物。在大多数情况下，高度不相容的元素会完全分离到熔体中，因此玄武岩中两种这样的元素的比例实际上与其来源中的比例相同。这也适用于较低程度的比例，如La/Sm和Zr/Nb，因为Zr和Sm不是高度不相容的元素。
The mantle can be sampled directly only very rarely. Geochemists have thus come to rely heavily on mantle-derived magmas to study the composition and evolution of the mantle. Only those compositional features that are unaffected by magmatic processes are useful as tracers of mantle processes. These include radiogenic isotope ratios such as those of He, Sr, Hf, and Os, stable isotope ratios, and ratios of highly incompatible elements or elements of similar incompatibility, such as Ba/Nb or Pb/Ce. The term “incompatible” denotes a preference of the element for a melt over mantle minerals. Highly incompatible elements will partition entirely into the melt under most circumstances, so that the ratio of two such elements in a basalt will be virtually identical to that ratio in its source. This is also true to a lesser degree of ratios such as La/Sm and Zr/Nb, as Zr and Sm are not highly incompatible elements.