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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Noble gases in the Finero phlogopite-peridotites, western Italian alps
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Noble gases in the Finero phlogopite-peridotites, western Italian alps

机译：意大利西部阿尔卑斯山的Finero金云母-橄榄岩中的稀有气体

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Here we report results from an investigation of noble gases in a specimen with layers of very fine-grained apatite and orthopyroxene from the Finero ultramafic complex, western Italian alps. We have also examined fresh olivine grains separated from phlogopite-harzburgites without an apatite layer. Fluid inclusions of these olivine separates appeared rich in radiogenic components such as He-4, Ne-21 and Ar-40, suggesting the derivation of fluids from a crust-like reservoir. Such a crust-like component also appeared to be contained in the samples with the apatite-opx layer, however, an additional isotopically distinct component is necessary to explain progressive increases in He-3 concentration and decreases in Ar-40/Ar-36 ratios observed approaching the apatite-rich layer. High He-3 contents and low Ar-40/Ar-36 ratios are consistent with the signature expected for slab-derived metasomatic fluids. There is a clear mixing trend defined in a He-3/Ar-36 vs. Ar-40/Ar-36 diagram with crustal and slab-derived fluids as end-member compositions, suggesting that the complex was metasomatised by fluids derived from geochemically distinct regions and distinct geotectonic settings. The parent melt or fluids responsible for the formation of the apatite-rich layer should be derived from the slab-derived component, which is consistent with the notion that the Finero mantle was once in the mantle wedge. An in situ component produced in the previously metasomatised portion of lithospheric mantle, or fluid released from surrounding metamorphic rocks during exhumation are possible sources for the crust-like component. (c) 2005 Elsevier B.V. All rights reserved.
机译：在这里，我们报告了来自意大利西部阿尔卑斯山的Finero超镁铁质复合物的样品中的稀有气体的调查结果，该样品中含有非常细的磷灰石和邻二甲苯。我们还检查了从金云母-哈氏石中分离出的没有橄榄石层的新鲜橄榄石颗粒。这些橄榄石分离物的流体包裹体似乎含有丰富的放射成因成分，例如He-4，Ne-21和Ar-40，这表明流体是从壳状储层中提取的。带有磷灰石-opx层的样品中似乎也包含这种类似壳的成分，但是，必须有一个额外的同位素不同成分才能解释He-3浓度的逐渐增加和Ar-40 / Ar-36比的降低观察到接近富磷灰石层。高的He-3含量和低的Ar-40 / Ar-36比值与平板衍生的交代液的预期特征一致。在He-3 / Ar-36与Ar-40 / Ar-36图中定义了明显的混合趋势，地壳和板状流体为末端成分，表明该复合物被地球化学衍生的流体交代了。不同的地区和不同的大地构造环境。负责形成富磷灰石层的母体熔体或流体应从板坯衍生的组分中推导，这与Finero地幔曾经位于地幔楔中的观点是一致的。在岩石圈地幔先前已被交代的部分中产生的原位成分，或在掘尸过程中从周围的变质岩中释放出的流体可能是地壳状成分的来源。 （c）2005 Elsevier B.V.保留所有权利。

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