Wüstite stability in the presence of a CO 2 -fluid and a carbonate-silicate melt: Implications for the graphite/diamond formation and generation of Fe-rich mantle metasomatic agents
Wüstite stability in the presence of a CO 2 -fluid and a carbonate-silicate melt: Implications for the graphite/diamond formation and generation of Fe-rich mantle metasomatic agents
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CO 2 流体和碳酸盐-硅酸盐熔体存在下的方铁矿稳定性：对石墨/金刚石形成和富铁地幔交代剂生成的影响
DOI：
10.1016/j.lithos.2015.12.001
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发表时间：
2016
期刊：
影响因子：
3.5
通讯作者：
Oleg A. Bayukov
中科院分区：
文献类型：
--
作者：
Y. Bataleva;Y. Palyanov;A. Sokol;Y. Borzdov;Oleg A. Bayukov
方铁体之间的相互作用的实验模拟气体溶解液,使用multianvil carbonate-silicate融化了高压split-sphere装置在FeO-MgO-CaO-SiO2-Al2O3-CO2system 6.3绩点的压力和温度范围内的1150°C - 1650°C和运行时的20 h。在相对低的温度下,脱二氧化碳反应系统中形成富含铁石榴石(Alm75Prp17Grs8) magnesiowustite (Mg #≤0.13),和气体溶解液。在此条件下，镁owstite能够将co2部分还原为co0，从而形成含Fe3+的镁owstite，形成磁铁矿和亚稳石墨结晶，形成金刚石种子。当温度≥1450℃时，体系中形成富铁碳酸盐-硅酸盐熔体（FeO ~ 56 wt.%, SiO2~ 12 wt.%）。（Fe,Mg）O, SiO2，流体和熔体之间的相互作用导致镁owstite氧化和铁矾石-磁铁矿尖晶石固溶体结晶（1450°C），以及镁owstite在碳酸盐-硅酸盐熔体（1550°C - 1650°C）中完全溶解。在碳酸盐-硅酸盐熔体和富含二氧化碳的流体存在的情况下，发现金刚石和亚稳石墨发生溶解（氧化）。研究结果表明，在富co2流体存在的岩石圈地幔压力下，w<s:1>硅镁石/镁ow<e:1>硅镁石只有在相对于富co2流体处于绝对过剩状态时才会在相对较低的温度下稳定。在这种情况下，会发生氧化还原反应，产生亚稳石墨和金刚石，同时将钨钛矿部分氧化为磁铁矿。在高浓度的富含二氧化碳的流体以及存在碳酸盐-硅酸盐熔体的情况下，w<s:1> stite是不稳定的：它要么被完全氧化，要么溶解在熔体或流体阶段，导致富Fe2 +和Fe3 +的碳酸盐-硅酸盐熔体的形成，这是岩石圈地幔中潜在的交代介质。
Experimental simulation of the interaction of wüstite with a CO2-rich fluid and a carbonate-silicate melt was performed using a multianvil high-pressure split-sphere apparatus in the FeO-MgO-CaO-SiO2-Al2O3-CO2system at a pressure of 6.3 GPa and temperatures in the range of 1150 °C–1650 °C and with run time of 20 h. At relatively low temperatures, decarbonation reactions occur in the system to form iron-rich garnet (Alm75Prp17Grs8), magnesiowüstite (Mg# ≤ 0.13), and CO2-rich fluid. Under these conditions, magnesiowüstite was found to be capable of partial reducing CO2to C0that leads to the formation of Fe3+-bearing magnesiowüstite, crystallization of magnetite and metastable graphite, and initial growth of diamond seeds. AtT≥ 1450 °C, an iron-rich carbonate-silicate melt (FeO ~ 56 wt.%, SiO2~ 12 wt.%) forms in the system. Interaction between (Fe,Mg)O, SiO2, fluid and melt leads to oxidation of magnesiowüstite and crystallization of fayalite-magnetite spinel solid solution (1450 °C) as well as to complete dissolution of magnesiowüstite in the carbonate-silicate melt (1550 °C–1650 °C). In the presence of both carbonate-silicate melt and CO2-rich fluid, dissolution (oxidation) of diamond and metastable graphite was found to occur. The study results demonstrate that under pressures of the lithospheric mantle in the presence of a CO2-rich fluid, wüstite/magnesiowüstite is stable only at relatively low temperatures when it is in the absolute excess relative to CO2-rich fluid. In this case, the redox reactions, which produce metastable graphite and diamond with concomitant partial oxidation of wüstite to magnetite, occur. Wüstite is unstable under high concentrations of a CO2-rich fluid as well as in the presence of a carbonate-silicate melt: it is either completely oxidized or dissolves in the melt or fluid phase, leading to the formation of Fe2 +- and Fe3 +-enriched carbonate-silicate melts, which are potential metasomatic agents in the lithospheric mantle.
影响因子：
64.8
作者：
Stagno, Vincenzo;Ojwang, Dickson O.;Frost, Daniel J.
通讯作者：
Frost, Daniel J.