Transportation process of transitional-metal elements by fluid and/or melt in the upper mantle beneath the arc

我们研究了两种不同类型的幔源橄榄岩，以澄清修改过程，特别是过渡金属元素的运输，通过熔体或板片衍生的流体：一个是从弧下地幔火山前缘下的捕虏体，另一个是固体侵入橄榄岩块和橄榄岩在阿曼蛇绿岩底部。火山前缘下的弧下地幔是高度交代的，某些元素（如微量元素、微量元素等）在弧下地幔中的含量较高。例如，在一个实施例中，Ni、Fe和铂族元素）部分富集于其中。此外，在弧下地幔包体中还发现了含H_2O的包裹体。然而，即使在弧源物质中也有不少H_2O包裹体的报道，我们证实了H_2O是火山前缘之下的次弧上地幔的主要流体相。

We examined two different types of mantle-derived peridotites to clarify modification processes, especially to transportation of transitional-metal elements, by melts or slab-derived fluids : the one is xenoliths from sub-arc mantle beneath the volcanic front and the other is solid intrusive peridotite blocks and peridotites at the bottom of Oman ophiolite. Then, we identified that the sub-arc mantle beneath the volcanic front is highly metasomatized and some elements(e. g., Ni, Fe and platinum-group elements) are partly concentrated in there. In addition, we found H_2O-bearing inclusions in sub-arc mantle xenoliths. However there have been quite a few reports of H_2O inclusions even in arc-derived materials, we confirmed that H_2O is the main fluid phase within the sub-arc upper mantle beneath the volcanic front.