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首页> 外文期刊>Contributions to Mineralogy and Petrology >Composition of primary kimberlite magma: constraints from melting and diamond dissolution experiments
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Composition of primary kimberlite magma: constraints from melting and diamond dissolution experiments

机译：金伯利岩岩浆的组成：融化和钻石溶解实验的限制

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Experiments are applied to constrain the composition of primary kimberlitic magmas which were in equilibrium with lithospheric peridotite and could resorb the entrained diamond to form typical dissolution features. The experiments are run on samples of a model carbonatite and a melt of the Udachnaya kimberlite at 6.3 GPa and 1400 degrees C, and at unbuffered or Re ReO2-buffered oxygen fugacity (1-2 log units above Ni-NiO). Near-liquidus dry Fe3+-free carbonatitic melt (derived from carbonated harzburgite) is saturated with the Ol-Grt-Opx-Mgs assemblage and is almost inert to diamond. Carbonatitic melts that bear 4.6-6.8 wt% Fe2O3 or 1.5 wt% H2O are in equilibrium only with Mgs +/- ol near the liquidus. Dissolution of diamond by these melts produces surface textures uncommon (corrosion sculptures) or common (negative-oriented trigons, shield-shaped laminae and elongate hillocks) to kimberlitic diamonds. The near-liquidus melt of the Udachnaya kimberlite (Yakutia) with 10-12 wt% H2O is saturated with the Ol-Grt-Cpx assemblage and may result from melting of carbonated garnet-bearing wehrlite. Hydrous kimberlitic melt likewise resorbs diamonds forming typical negative-oriented trigons, shield-shaped laminae and elongate hillocks on their surfaces. Therefore, the melts that could originate in the thermal conditions of subcratonic lithosphere, entrain diamond and dissolve it to produce dissolution features on crystal surfaces, were compositionally close to kimberlite (16-19 wt% SiO2) and rich in H2O. Dry Fe3+-bearing carbonatites with fO(2) controlled by the ferric/ferrous equilibrium slightly above the Ni-NiO buffer cannot be diamond carriers.
机译：进行了实验，以限制与岩石圈橄榄岩平衡的金伯利岩岩浆初生岩浆的成分，并且可以吸收夹带的钻石以形成典型的溶蚀特征。实验是在6.3 GPa和1400摄氏度，无缓冲或Re ReO2缓冲的氧气逸度（高于Ni-NiO 1-2 log单位）的情况下，对模型碳酸盐样品和Udachnaya金伯利岩的熔融液进行的。接近液相线的不含Fe3 +的干碳酸盐熔体（源自碳酸钙矿质）由Ol-Grt-Opx-Mgs组合物饱和，并且几乎对金刚石呈惰性。含4.6-6.8 wt％Fe2O3或1.5 wt％H2O的碳酸盐熔体仅与液相线附近的Mgs +/- ol处于平衡状态。这些熔体溶解钻石会产生金伯利岩钻石罕见的表面纹理（腐蚀雕塑）或常见的表面纹理（负向三角形，盾形薄片和细长的小丘）。具有10-12 wt％H2O的Udachnaya kimberlite（Yakutia）的接近液相线熔体被Ol-Grt-Cpx组合物饱和，并且可能是由于含碳酸石榴石的辉绿岩的熔融所致。含水的金伯利岩熔体同样吸收钻石，在其表面形成典型的负向三角形，盾形薄片和细长小丘。因此，可能源自亚克拉通岩石圈热条件的熔融物，夹带金刚石并将其溶解以在晶体表面上产生溶解特征，其成分在成分上接近金伯利岩（16-19 wt％SiO2），并且富含H2O。 fO（2）受含铁/亚铁平衡控制且略高于Ni-NiO缓冲液的干式含Fe3 +碳酸盐岩不能成为金刚石载体。

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