Geochemical and Sr. Ndisotopic characteristics and P. T estimates of mantle xenoliths from the French Massif Central : evidence for melting and multiplemetasomatism by silicate-rich carbonatiteand asthenospheric melts
Geochemical and Sr. Ndisotopic characteristics and P. T estimates of mantle xenoliths from the French Massif Central : evidence for melting and multiplemetasomatism by silicate-rich carbonatiteand asthenospheric melts
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法国中央地块地幔捕虏体的地球化学和Sr.N同位素特征及P.T估计:富含硅酸盐的碳酸岩和软流圈熔体的熔融和多重交代作用的证据
DOI：
10.1144/sp337.8
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
J.
中科院分区：
文献类型：
--
作者：
Yoshikawa;M.;Kawamoto;T.;Shibata;T.;Yamamoto;J.
法国中央地块的Mont Briançon、Ray Pic和Puy Beaunit的超镁铁质捕虏体显示出不同的矿物成分，表明肥沃橄榄岩经过不同程度的部分熔融后仍有残余来源。单斜辉石的微量元素和Sr-Nd同位素变化反映了亏损地幔与软流圈熔体和硅酸盐碳酸岩熔体等富集组分的混合作用。辉石地质温度计和CO2地质压力计的估计值为：Mont Briançon在0.92-1.10 GPa下为860-1060 C，Ray Pic在0.89-1.04 GPa下为930-980 C，Puy Beaunit在0.59-0.71 GPa下为840-940 C。捕虏体从南到北具有以下特征：（1）来源由深变浅;（2）矿物成分亏损，表明部分熔融程度较高;（3）同位素和微量元素富集，表明捕虏体可能在华力西俯冲过程中与以高H2O和K2 O为特征的富硅酸盐碳酸盐熔体发生了混合作用。
Ultramafic xenoliths from Mont Briançon, Ray Pic and Puy Beaunit in the French Massif Central show variable mineral compositions that indicate a residual origin after various degrees of partial melting of a fertile peridotite. Furthermore, trace element and Sr–Nd isotopic variations of clinopyroxenes indicate mixing processes between depleted mantle and enriched components such as asthenospheric melt and silicate carbonatite melt. Pyroxene geothermometer and CO 2 geobarometer estimates are 860–1060 C at 0.92–1.10 GPa for Mont Briançon, 930–980 C at 0.89–1.04 GPa for Ray Pic and 840–940 C at 0.59–0.71 GPa for Puy Beaunit. From south to north, the xenoliths show the following trends:(1) deeper to shallower origin;(2) more depleted mineral compositions, suggesting higher degrees of partial melting; and (3) more enriched isotopes and trace elements, indicating a mixing process with a silicate-rich carbonatite melt characterized by high H 2 O and K 2 O, possibly during Variscan subduction.