Ophiolitic trondhjemites: a possible analogue for Hadean felsic 'crust'
Ophiolitic trondhjemites: a possible analogue for Hadean felsic 'crust'
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蛇绿质长石岩：可能是冥古宙长英质“地壳”的类似物
DOI：
10.1111/j.1365-3121.2008.00829.x
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发表时间：
2008
期刊：
影响因子：
2.4
通讯作者：
H. Rollinson
中科院分区：
文献类型：
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作者：
H. Rollinson
有人认为，保存在西澳大利亚杰克山沉积物中的>；4.0 Ga碎屑锆石，保存了4.4-4.5 Ga以前地球上发育良好的陆壳的证据。这里表明，杰克山锆石与蛇绿岩序列中的奥长花岗岩中的锆石具有相似的地球化学特征，这表明地球上第一个长英质地壳的形成方式可能类似于现代蛇绿岩玄武岩。阿曼蛇绿岩中的奥长花岗岩是由轴向岩浆房顶板带上部(角闪辉长岩)的水合部分熔融形成的。类似的镁铁质原岩的水合熔融可能在海德期进行过，在以镁铁质为主的地壳中产生了少量的长英质岩石，因此不需要假设长英质陆壳的年龄为4.4-4.5 Ga。
It has been argued that >4.0 Ga detrital zircons preserved in sediments of the Jack Hills, western Australia, preserve evidence for a well‐developed continental crust on the Earth at 4.4–4.5 Ga ago. Here, it is shown that there are geochemical similarities between the Jack Hills zircons and the zircons found in trondhjemites in ophiolite sequences, suggesting that the Earth's first felsic crust may have formed in a manner analogous to modern ophiolitic trondhjemites. The trondhjemites of the Oman ophiolite were formed by the hydrous partial melting of the upper (hornblende) gabbros in the roof‐zone of an axial magma chamber. A similar hydrous melting of a mafic protolith may have operated during the Hadean, to create small volumes of felsic rocks within a dominantly mafic crust, obviating the need to postulate a felsic continental crust at 4.4–4.5 Ga.