| 橄榄岩中尖晶石化学成分分带的机理及其地质意义 |
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| 引用本文： | 李建平 Provo,A.橄榄岩中尖晶石化学成分分带的机理及其地质意义[J].矿物学报,1997,17(2):156-163. |
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| 作者姓名： | 李建平 Provo A |
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| 作者单位： | 中国科学院广州地球化学研究所!广州，510640，法国布莱斯帕斯卡大学地质系!克莱蒙非朗，63038，法国布莱斯帕斯卡大学地质系!克莱蒙非朗，63038 |
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| 摘 要： | 橄榄岩中尖晶石的化学成分分带显示，在由温度降低引起的亚固相平衡过程中，与橄榄石及斜方辉石相邻的尖晶石边缘贫Mg和Al、富Fe和Cr，而与单斜辉石相邻的尖晶石边线相反。尖晶石的Fe和Mg分带为其他矿物的粒间Fe－Mg离子扩散所致；尖晶石中的Cr和Al分带则是尖晶石晶体内部Cr－Al离子的交互扩散所致。本文从热力学理论角度说明了尖晶石晶体内部的Cr－Al交互扩散受其Fe－Mg分带的控制；从热力学计算证明了尖晶石内Al必须从富Fe处向富Mg处扩散，解释了尖晶石中Mg和Al及Fe和Cr分带的一致性。
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| 关 键 词： | 尖晶石 化学成分分带 化学平衡 离子扩散 |
MECHANISM OF CHEMICAL ZONATION OF SPINEL IN PERIDOTITE AND ITS GEOLOGICAL SIGNIFICANCE |
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| Li Jianping, A. Provost , J. Kornprobst.MECHANISM OF CHEMICAL ZONATION OF SPINEL IN PERIDOTITE AND ITS GEOLOGICAL SIGNIFICANCE[J].Acta Mineralogica Sinica,1997,17(2):156-163. |
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| Authors: | Li Jianping A Provost J Kornprobst |
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| Abstract: | Chemical zoning in spinel included in peridotite show that during subsolidus equilibriumcaused by temperature rise, the spinel in contact with olivine and orthopyroxene is poor in Mg andAl and rich in Fe and Cr at the rim, but it is inverse for the spinel in contact with clinopyroxene.Fe and Mg zoning in spinel results from intergranular diffusion of Fe-Mg cations with other miner-als while Cr and Al zoning in spinel results from intergranular diffusion of Cr-Al cations in spinelcrystal- It is pointed out that the Cr-Al reciprocal diffusion in spinel is controlled by Mg-Fe zoningfrom the view of thermodynamic theory. The thermodynamic calculation indicates that Al mustdiffuse from the position where Fe is enriched to the position where Mg is enriched in spinel. Thisexplains why Mg and Fe zonation is always consistent with Al and Cr zonation, respectively. |
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| Keywords: | spinel chemical zoning chemical equilibration cation diffusion |
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