下地幔温压条件下碳对（Mg,Fe）SiO3布里奇曼石的影响  

Effects of Carbon on（Mg,Fe）SiO3 Bridgmanite under the Lower Mantle Pressure-Temperature Conditions

作　　者：苘廉洁 苑洪胜 秦礼萍[1] 张莉 MAN Lianjie;YUAN Hongsheng;QIN Liping;ZHANG Li(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China;Center for High Pressure Science and Technology Advanced Research(HPSTAR),Beijing 100094,China)

机构地区：[1]中国科学技术大学地球和空间科学学院,安徽合肥230026 [2]北京高压科学研究中心,北京100094

出　　处：《高压物理学报》2019年第6期10-19,共10页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金(41574080,U1530402);中国工程物理研究院院长基金(201402032)

摘　　要：利用激光加温金刚石对顶砧技术模拟下地幔温压条件(36~88 GPa,1850~2800 K),探索了碳与含铁的(Mg,Fe)SiO3布里奇曼石的相互作用过程。同步辐射X射线衍射实验表明,(Mg,Fe)SiO3布里奇曼石与碳在大于42 GPa、2000 K的温压条件下发生了氧化还原反应,即(Mg,Fe)SiO3布里奇曼石中的二价铁(Fe^2+)被单质碳还原成金属铁(Fe^0);而在较低的温压条件下,布里奇曼石中的Fe2+可以稳定存在。该结果表明,在下地幔深部的温压条件下,CCO缓冲的氧逸度值比IW缓冲更低,热力学计算结果也证实了这一结果。实验结果为地幔深部氧化还原条件的不均一性和局部极端还原状态的出现提供了解释。In this study we investigated the interaction of carbon with iron in the(Mg,Fe)SiO3 bridgmanite under the conditions corresponding to the Earth’s lower mantle(36–88 GPa,1850–2800 K)using a laserheated diamond anvil cell.Synchrotron X-ray diffraction measurements of the run products showed that Fe^2+in bridgmanite can be reduced to metallic Fe by carbon under the pressure and temperature conditions higher than 42 GPa and 2000 K.The coexisting metallic Fe and Fe-depleted bridgmanite in the run products suggests that the CCO buffer produces lower oxygen fugacity than the of Fe-Fe^O(IW)buffer,which is further confirmed by the thermodynamic calculation.The experimental results in this study could provide a potential explanation for the presence of redox heterogeneities and highly reducing regions in the deep mantle.

关 键 词：布里奇曼石 深部碳 下地幔 氧化还原反应 

分 类 号：O521.2[理学—高压高温物理]