Eclogites as palaeodynamic archives: Evidence for warm (not hot) and depleted (but heterogeneous) Archaean ambient mantle
Eclogites as palaeodynamic archives: Evidence for warm (not hot) and depleted (but heterogeneous) Archaean ambient mantle
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DOI：
10.1016/j.epsl.2018.10.025
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发表时间：
2019-01-01
影响因子：
5.3
通讯作者：
Arndt, Nicholas T.
中科院分区：
文献类型：
--
作者：
Aulbach, Sonja;Arndt, Nicholas T.
一些高镁榴辉岩捕虏体，被来自古代大陆核心地幔岩石圈的金伯利岩夹带，以及在古洋盆闭合过程中挖出或仰冲的稀有造山榴辉岩和蛇绿岩，其元素和同位素组成表明原岩是由古代洋底喷发的小分化熔体形成的。尽管发生变质作用和部分熔失，这些古代大洋中脊玄武岩和苦铁矿样本仍然保留了其原岩周围对流地幔来源的化学和物理状态的记忆。已发表的数据表明，当过滤排除具有累积原岩的样本或显示后来富集（交代作用）的证据时，样品相对于 TiO2 和 MgO 缺乏 Y 或 Al2O3 消耗。这表明原岩的熔体偏析主要来自不含石榴石的橄榄岩源，并且意味着低压下固相线的相交（
Some high-Mg eclogite xenoliths, entrained by kimberlites from the mantle lithospheres of ancient continental cores, and rare orogenic eclogites and ophiolites, exhumed or obducted during the closure of palaeo-ocean basins, have elemental and isotopic compositions indicative of protoliths that formed as little-differentiated melts erupted in ancient ocean floors. Despite metamorphism and, in part, partial melt loss, these samples of ancient mid-ocean ridge basalt and picrite retain a memory of the chemical and physical state of their protoliths' ambient convecting mantle sources. Published data show that, when filtered to exclude specimens with cumulate protoliths or showing evidence for later enrichment (metasomatism), the samples lack Y or Al2O3 depletion relative to TiO2 and MgO. This indicates melt segregation of the protolith predominantly from a garnet-free peridotite source and implies intersection of the solidus at low pressures (