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首页> 外文期刊>Contributions to Mineralogy and Petrology >Multistage evolution of the European lithospheric mantle: new evidence from Sardinian peridotite xenoliths
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Multistage evolution of the European lithospheric mantle: new evidence from Sardinian peridotite xenoliths

机译：欧洲岩石圈地幔的多阶段演化：撒丁岛橄榄岩橄榄岩异质岩的新证据

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Peridotite xenoliths entrained in Plio-Pleistocene alkali basalts from Sardinia represent fragments of the uppermost lithospheric mantle, and are characterised by an anhydrous four-phase mineral assemblage. They range in bulk rock composition from fertile spinel–lherzolites to residual spinel–harzburgites. The Sr–Nd isotope and trace element composition of clinopyroxene mineral separates varies between LREE-depleted samples with 87Sr/86Sr as low as 0.70262 and 143Nd/144Nd up to 0.51323 and LREE-enriched samples with 87Sr/86Sr up to 0.70461 and 143Nd/144Nd down to 0.51252. The available data suggest that all the studied peridotite samples suffered variable degrees of partial melting during Pre-Mesozoic times (based on Nd model ages relative to CHUR and DMM). The overprinted enrichment is related to a subsequent metasomatism, induced by fluids rising through the lithosphere that preferentially percolated the originally most depleted domains. Despite the occurrence of orogenic volcanism in the area, preferential enrichment in elements typically associated with slab derived fluids/melts (K, Rb, Sr, Th) relative to LREE has not been detected, and metasomatism seems to be more likely related to the infiltration of highly alkaline basic melts characterised by an EM-like Sr–Nd isotopic composition. Similar 87Sr/86Sr–143Nd/144Nd compositions, characterised by an EM signature, are observed in anorogenic mafic lavas and peridotite xenoliths from widespread localities within the "European" plate, whereas they have not previously been recorded in peridotite xenoliths and associated alkaline mafic lavas from the stable "African" lithospheric domain.
机译：来自撒丁岛的上新世-上新世碱性玄武岩夹带的橄榄岩异岩代表最岩石圈地幔的碎片，其特征是无水的四相矿物组合。它们的块岩组成从肥沃的尖晶石-锂铁矿到残留的尖晶石-哈氏石。贫富稀土样品中，斜辉石矿物分离物的Sr-Nd同位素和微量元素组成因87 Sr / 86 Sr低至0.70262和143 Nd / 144 而异Nd高达0.51323，富含LREE的样品中87 Sr / 86 Sr高达0.70461，143 Nd / 144 Nd下降至0.51252。现有数据表明，所有研究过的橄榄岩样品在中生代时期都经历了不同程度的部分融化（基于相对于CHUR和DMM的Nd模型年龄）。叠印的富集与随后的交代作用有关，后者由岩石圈中上升的流体优先渗透最初最贫乏的区域引起。尽管该地区发生了造山活动的火山活动，但相对于LREE，通常未发现与板坯衍生的流体/熔体（K，Rb，Sr，Th）有关的元素优先富集，而交代作用似乎更可能与渗透有关。高碱性的基础熔体，其特征是具有类似EM的Sr-Nd同位素组成。在成因的镁铁质熔岩和橄榄岩异岩中，从该地区广泛分布的地方观察到相似的87 Sr / 86 Sr–143 Nd / 144 Nd成分，具有EM签名。 “欧洲”板块，而以前从未在稳定的“非洲”岩石圈区域的橄榄岩异岩和相关的碱性镁铁质熔岩中记录到它们。

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  • 来源
    《Contributions to Mineralogy and Petrology》 |2001年第3期|284-297|共14页
  • 作者

    Luigi Beccaluva; Gianluca Bianchini; Massimo Coltorti; William Perkins; Franca Siena; Carmela Vaccaro; Marjorie Wilson;

  • 作者单位

    Department of Earth Sciences University of Ferrara Corso Ercole I D'este 32 44100 Ferrara Italy;

    Department of Earth Sciences University of Ferrara Corso Ercole I D'este 32 44100 Ferrara Italy;

    Department of Earth Sciences University of Ferrara Corso Ercole I D'este 32 44100 Ferrara Italy;

    Institute of Geography and Earth Sciences University of Wales Aberystwyth Dyfed SY23 3DB UK;

    Department of Earth Sciences University of Ferrara Corso Ercole I D'este 32 44100 Ferrara Italy;

    Department of Earth Sciences University of Ferrara Corso Ercole I D'este 32 44100 Ferrara Italy;

    School of Earth Sciences Leeds University Leeds LS2 9JT UK;

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