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首页> 外文期刊>Contributions to Mineralogy and Petrology >Mantle melting in equilibrium with an Iron-Wustite-Graphite buffered COH-fluid
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Mantle melting in equilibrium with an Iron-Wustite-Graphite buffered COH-fluid

机译：用铁-石墨-石墨缓冲的COH流体平衡地幔融化

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Partial melting experiments on a San Carlos peridotite were done in a Walker type multi-anvil press at pressures from 5 to 12.5 GPa. Experiments were done in the presence of a COH-fluid and at oxygen fugacity controlled by the Fe-FeO buffer. Olivine, clinopyroxene, garnet and orthopyroxene are stable in all but the highest temperature 10 GPa experiments where olivine and garnet coexist, and the highest temperature 5 GPa experiments where olivine is the single crystalline phase. The solidus at 5 GPa was found to be at approximately l,200 deg C and the liquidus was estimated to be at 1,325 deg C, which is approx 500 deg C lower than has been reported for dry melting of peridotite. The aluminum concentration of the melts decreases with increasing melt fraction and decreases also with increasing pressure. At 5 GPa the melts have a CaO/ Al_2O_3-ratio of 0.85-1.0, which is similar to that of un-depleted komatiites; major element concentrations are also identical to those of undepleted komatiites such as the Munro komatiites. At 10 and 12.5 GPa the partial melts have CaO/Al_2O_3-ratios above 1.5 and major element composition almost identical to aluminum depleted komatiites such as the Barberton komatiites. We therefore conclude that in the presence of a reducing COH-fluid both aluminum-depleted and -undepleted komatiites could have formed at temperatures much lower than generally accepted.
机译：在Walker型多砧压机上，在5至12.5 GPa的压力下，对San Carlos橄榄岩进行了部分熔融实验。实验是在有COH流体存在且氧逸度受Fe-FeO缓冲液控制的情况下进行的。除橄榄石和石榴石共存的最高温度10 GPa实验外，橄榄石为单晶相的最高温度5 GPa实验外，橄榄石，斜辉石，石榴石和邻苯二酚在所有温度下均稳定。发现5 GPa的固相线大约为1200℃，液相线估计为1325℃，这比橄榄岩的干法熔融所报道的低约500℃。熔体的铝浓度随着熔体分数的增加而降低，并且也随着压力的增加而降低。在5 GPa时，熔体的CaO / Al_2O_3-比率为0.85-1.0，这与未耗尽的科马铁矿相似。主要元素的浓度也与未消耗的科马铁矿如芒罗科马铁矿相同。在10 GPa和12.5 GPa时，部分熔体的CaO / Al_2O_3比率高于1.5，主要元素组成几乎与贫铝的科马铁矿（如Barberton科马铁矿）相同。因此，我们得出结论，在存在还原性COH流体的情况下，贫铝和未缺失的科马铁矿可能在比普遍接受的温度低得多的温度下形成。

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