Incompatible-element enrichment in Archean basalts: A consequence of contamination by older sialic crust rather than mantle heterogeneity
Incompatible-element enrichment in Archean basalts: A consequence of contamination by older sialic crust rather than mantle heterogeneity
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太古代玄武岩中不相容元素的富集：古老硅质地壳而非地幔异质性污染的结果
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发表时间：
1986
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通讯作者：
M. Barley
中科院分区：
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作者：
M. Barley
西澳大利亚富镁太古宙玄武岩中不相容元素的高丰度，被认为来自富集的地幔源，可能是原始岩浆被少量的古硅质地壳污染的结果。由于这些熔岩代表了在太古宙玄武岩中观察到的不相容元素富集的一些更极端的情况，因此有可能通过地幔源岩浆的可变地壳污染来解释许多以前归因于非均质太古宙地幔的微量元素变化。最近对热侵蚀速率的计算预测，在太古宙中丰富的高温高mgo岩浆最容易受到污染；因此，在确定太古宙地幔非均质性的真实程度之前，需要对太古宙绿岩带的同位素和微量元素资料进行谨慎的重新评价。
High abundances of incompatible elements in MgO-rich Archean basalts from Western Australia, which were thought to have been derived from an enriched mantle source, are probably the result of contamination of primitive magmas by small amounts of older sialic crust. Because these lavas represent some of the more extreme cases of enrichment in incompatible elements observed in Archean basalts, it may be possible to explain much of the trace-element variation previously ascribed to a heterogenous Archean mantle by variable crustal contamination of mantle-derived magmas. Recent calculations of thermal erosion rates predict that high-temperature high-MgO magmas, abundant in the Archean, are most susceptible to contamination; therefore, a cautious reappraisal of isotopic and trace-element data from Archean greenstone belts is required before the real extent of Archean mantle heterogeneity can be established.