Experimental investigation of phase transformations of olivine and enstatite at the lower part of the mantle transition zone:Implications for structure of the 660 km seismic discontinuity  

作　　者：WU Yao ZHANG YanFei WANG YanBin JIN ZhenMin DONG ShuWen 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences [2]Chinese Academy of Geological Sciences

出　　处：《Science China Earth Sciences》2014年第4期592-599,共8页中国科学（地球科学英文版）

基　　金：financially supported by the Sinoprobe-0801;National Natural Science Foundation of China(Grant Nos.41002068&41174076)

摘　　要：High-pressure polymorphs of olivine and enstatite are major constituent minerals in the mantle transition zone （MTZ）. The phase transformations of olivine and enstatite at pressure and temperature conditions corresponding to the lower part of the MTZ are import for understanding the nature of the 660 km seismic discontinuity. In this study, we determine phase transfor- mations of olivine （MgSi204） and enstatite （MgSiO3） systematiclly at pressures between 21.3 and 24.4 GPa and at a constant temperature of 1600~C. The most profound discrepancy between olivine and enstatite phase transformation is the occurency of perovskite. In the olivine system, the post-spinel transformation occures at 23.8 GPa, corresponding to a depth of 660 km. In contrast, perovskite appears at 〈23 GPa （640 km） in the enstatite splitting of the 660 km seismic discountinuity under eastern China. system. The -1 GPa gap could explain the uplifting and/orsplitting of the 660 km seismic discountinuity under eastern China.橄榄石和顽火石的高压的多形体是在披风转变地区(MTZ ) 的主要成分矿物质。在压力和相应于 MTZ 的更低的部分的温度条件的橄榄石和顽火石的阶段转变是为理解 660 km 的性质的进口地震断绝。在这研究，我们在在 21.3 和 24.4 GPa 之间的压力并且在 1600 的经常的温度 systematiclly 决定橄榄石(MgSi2O4 ) 和顽火石(MgSiO3 ) 的阶段转变 ????????? 欠 ?? ??? 吗？？

关 键 词：OLIVINE ENSTATITE high-pressure phase transformation 660 km seismic discontinuity mantle transition zone eastern China 

分 类 号：P589[天文地球—岩石学]