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产于克拉通内部的高镁(Mg#>45)安山岩受到地学界的高度关注,目前对于高镁安山岩的成因仍然存在明显的争议.为了对已有基于岩石学和地球化学研究推断的克拉通内部高镁安山岩成因认识进行检验并提供直接的证据,我们在六面顶压机上开展了1250～1400℃,2.0～5.0 GPa条件下英云闪长质熔体与地幔橄榄石反应的高温高压实验,模拟研究拆沉到地幔的榴辉岩化下地壳部分熔融产生的熔体与地幔橄榄岩的反应.实验结果显示,反应后熔体的化学组成与华北克拉通内部高镁安山岩有很相似的变化.因此,榴辉岩化下地壳部分熔融产生的英云闪长质熔体与地幔橄榄岩的反应可能是形成克拉通内部高镁安山岩的重要机制之一.
The high magnesium (Mg #> 45) andesite produced in the interior of the craton is highly concerned by the geoscience community and there is still a clear controversy over the genesis of the high-magnesium andesite.In order to analyze the existing craton Internal high-Mg andesite understanding of the origin of the test and provide direct evidence, we carried out in the six-sided top press 1250 ~ 1400 ℃, 2.0 ~ 5.0 GPa under the conditions of the Ying-diorite melt and mantle olivine reaction temperature and pressure Experiments and simulations were conducted to investigate the reaction between the melts and the mantle peridotite produced by partial melting of the crust subducted by eclogite-lithification in the mantle. The experimental results show that the chemical composition of the melt after the reaction is similar to that of the high-Mg andesite in the North China Craton Therefore, the reaction of the eclogitic dioritic melt with the mantle peridotite produced by the partial melting of the lower eclogite crust may be one of the important mechanisms for forming the high-Mg andesite in the craton.