Co-existing fluid and silicate inclusions in mantle diamond
Co-existing fluid and silicate inclusions in mantle diamond
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DOI：
10.1016/j.epsl.2006.08.005
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发表时间：
2006-10
影响因子：
5.3
通讯作者：
E. Tomlinson;A. Jones;J. Harris
中科院分区：
文献类型：
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作者：
E. Tomlinson;A. Jones;J. Harris
我们记录了加拿大熊猫金伯利岩8颗包覆钻石纤维层中共存的硅酸盐宏观包裹体和流体微观包裹体的组成。金刚石外壳中的矿物包裹体要么来自橄榄岩套件（铬-白云石、正辉石、橄榄石和铬透辉石），要么来自榴辉岩套件（辉长石）。因此，纤维状钻石生长在与八面体钻石相同的共生环境中。与熊猫和世界各地的八面体钻石的等效相相比，包裹体的来源成分更丰富（低Mg#和高CaO）。然而，石榴石和斜辉石包裹体中中等至高的cr2o3含量表明，这种明显的生育是由于二次过程。硅酸盐包裹体的地热测量结果显示其平衡温度较低，为930 ~ 1010℃。共存流体微包裹体以H2O、碳酸盐和KCl为主。橄榄岩和榴辉岩样品中的流体包裹体沿Fe-Ca-Mg -碳酸盐岩和KCl之间的线性排列排列。一个榴辉岩样品中的包裹体也含有石英。我们认为，钻石既捕获了交代矿物，也捕获了交代流体，因此提供了地幔交代事件的快照。
We document the compositions of co-existing silicate macro-inclusions and fluid micro-inclusions in the fibrous coats of eight coated diamonds from the Panda kimberlite (Canada). The mineral inclusions in the diamond coats come from either the peridotite suite (Cr-pyrope, orthopyroxene, olivine and Cr-diopside) or the eclogite suite (omphacite). Therefore, fibrous diamonds grow in the same paragenetic environments as octahedral diamonds. The inclusions document a more fertile source composition (lower Mg# and higher CaO) than for equivalent phases in octahedral diamonds from Panda and worldwide. However, moderate to high Cr2O3contents in garnet and clinopyroxene inclusions suggest that this apparent fertility is due to a secondary process. Geothermometry of the silicate inclusions yields low equilibration temperatures of 930 to 1010 °C. The co-existing fluid micro-inclusions are dominated by H2O, carbonate and KCl. Fluid inclusions in both the peridotitic and eclogitic samples fall along linear arrays between Fe–Ca–Mg carbonate and KCl. Inclusions in the one eclogitic sample also contain quartz. We suggest that the diamonds have trapped both metasomatised minerals and the metasomatic fluid, and so provide a snap shot of a metasomatic event in the mantle.