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

对来自西班牙塔兰特和日本西南部高岛的富斜辉石包体进行了研究。它们是由板岩熔体(埃达克岩熔体)和地幔橄榄岩之间的反应形成的。它们的单斜辉石在微量元素特征和稀土配分模式上与奥夫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OPX辉石岩包体的信息。它们可能来自地幔楔体内埃达克质熔体的管道。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，而橄榄石的沉淀是以牺牲橄榄石为代价的。塔兰特斜方辉石岩中含有富Nb金红石等富HFSE矿物，相对LILE而言，富含HFSE。这意味着上述反应可以产生分馏板条衍生熔体的负峰值。这种辉石岩中的斜方辉石，在这里被认为是板片熔体/橄榄岩反应产物，与被解释为流体/橄榄岩反应产物的辉石截然不同，后者被描述为Avahc和伊拉亚火山。本文叙述了侵位于Sangun High P/Low T片岩中的Ochiai-Hokubo杂岩中变质/交代橄榄岩的地球化学分析，类似于地幔-楔状橄榄岩与板片的相互作用。橄榄岩除了H2O外，还明显富含Rb和Cs，这些元素集中在交代形成的钠闪石中。

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.