Formation and modification of the mantle wedge : from the ocean to the confinent

本文对西班牙塔兰特和日本西南部高岛的富斜方辉石捕虏体进行了研究。它们是由板片熔体（埃达克岩熔体）与地幔橄榄岩反应形成的。它们的单斜辉石在微量元素特征和稀土元素模式上与来自阿尤蒂安弧阿达克岛的单斜辉石斑晶埃达克岩相似。这可能表明，埃达克质熔体参与了塔兰特和高岛富辉石捕虏体的信息。它们可能来源于地幔楔中埃达克质熔体的通道。因此，埃达克岩的化学成分趋势基本上是由斜方辉石的沉淀控制的，而橄榄石的沉淀则是主要的。塔兰特斜辉石岩中含有富铌金红石等高场强矿物，且高场强矿物相对于大离子亲石富集。这意味着上述反应可产生HFSE的负尖峰至分馏板衍生的熔体。斜方辉石在这样的辉石岩，interpereted在这里是一个板熔体/橄榄岩反应产物，是明显不同的oryhopyroxene被解释为流体/橄榄岩反应产物，描述从Avahc火山和Pakuya火山。我们已经陈述了一个变质/交代橄榄岩的落合-北保岩，侵位到三郡高P/低T片岩，作为一个类似的地幔楔橄榄岩与板片相互作用的地球化学分析。橄榄岩明显富集Rb和Cs，除H_2O，这些元素集中在交代形成的钠透闪石。

Orthopyroxene-rich xenoliths from Tallante, Spain, and Takashima, SW Japan, have been investigated. They were farmed by a reaction between the slab melt(adakite melt) and the mantle peridotite. Their dinopyroxene is similar in trace-element characteristics and REE pattern to clinopyroxene phenocrystin adakite from Adak Island of the Aeutian arc. This may indicate that an adakitic melt was involved information of the opx-rich pyroxenite xenoliths from Tallante and Takashima. They possibly derived from the conduit of adakitic melt within the mantle wedge. The chemical compositional trend of adakite is, therefore, basically controlled by precipitation of orthopyroxene at the expense of olivine. The orthopyroxenite from Tallante contains some HFSE-rich minerals such as Nb-rich rutile, and is enriched with HFSE relative to LILE. This means that the reaction above can yield negative spikes of HFSE to the fractionating slab-derived melt. The orthopyroxene in such pyroxenites, interpereted here to be a slab-melt/peridotite reaction product, is distinctively different from the oryhopyroxene that is interpreted to be fluid/peridotite reaction product, described from Avahc and Iraya volcanoes. We have stated a geochemical analysis of metamorphosed/metasomatized peridotite of the Ochiai-Hokubo comprex, emplaced into the Sangun highP/low T schist, as an analogue to mantle-wedge peridotite interacting with slab. The peridotite is clearly enriched with Rb and Cs in addition to H2O, and these dements are concentrated in metasomatically formed Na-trermolite.