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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Sulfide melts-graphite interaction at HPHT conditions: Implications for diamond genesis
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Sulfide melts-graphite interaction at HPHT conditions: Implications for diamond genesis

机译：HPHT条件下的硫化物熔体-石墨相互作用：对金刚石成因的启示

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The interaction of graphite with (Fe,Ni)(9)S-8 and FeS sulfide melts has been studied at P = 6.3-7.5 GPa and T = 1450-2200 degrees C in experiments with a duration from 2 to 65 h. It has been found that both pentlandite and pyrrhotite melts interacting with graphite show similar behavior. At < 7.5 GPa and 1450-1800 degrees C and at 7.5 GPa and 1600 degrees C carbon crystallizes predominantly as metastable graphite and to the minor extent as diamond on the seed crystals. Only at a pressure of 7.5 GPa and a temperature of 1600 degrees C and higher, sulfide melts provide spontaneous diamond nucleation at the melt-graphite interface and directly within carbon-saturated sulfide melt. In this case no metastable graphite was found in the products. Diamond crystals synthesized in the (Fe,Ni)(9)S-8-C system were found to contain nitrogen impurity with concentrations of an order of 1000 ppm and exhibited IR absorption peaks due to hydrogen. The luminescence measurements revealed specific optical centers related to nickel impurity in the crystals. It is concluded that sulfide melts are less efficient diamond forming media as compared to carbonate, carbonate-silicate-fluid and fluid systems. The results of the study suggest that diamond nucleation from carbon-supersaturated sulfide melt as supposed in the sulfide model of diamond genesis seems improbable at the UHP conditions of the formation of most natural diamonds. (c) 2006 Elsevier B.V. All rights reserved.
机译：在2至65小时的实验中，研究了石墨与（Fe，Ni）（9）S-8和FeS硫化物熔体的相互作用，其温度为P = 6.3-7.5 GPa和T = 1450-2200摄氏度。已经发现，与石墨相互作用的五方石和黄铁矿熔体均表现出相似的行为。在<7.5 GPa和1450-1800摄氏度下以及在7.5 GPa和1600摄氏度下，碳主要作为亚稳态石墨结晶，而在较小程度上作为晶种上的金刚石结晶。仅在7.5 GPa的压力和1600摄氏度及更高的温度下，硫化物熔体才能在熔体-石墨界面处以及直接在碳饱和的硫化物熔体中提供自发的金刚石成核作用。在这种情况下，在产物中未发现亚稳态石墨。发现在（Fe，Ni）（9）S-8-C系统中合成的金刚石晶体含有氮杂质，其浓度约为1000 ppm，并且由于氢而显示出IR吸收峰。发光测量揭示了与晶体中镍杂质有关的特定光学中心。结论是，与碳酸盐，碳酸盐-硅酸盐-流体和流体系统相比，硫化物熔体是效率较低的金刚石形成介质。研究结果表明，在大多数天然钻石形成的超高压条件下，钻石超生碳模型中所假设的碳过饱和硫化物熔体中的钻石成核似乎是不可能的。 （c）2006 Elsevier B.V.保留所有权利。

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