作　　者： ; ; ; (费英伟）;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《矿物学报》 2005年第1期45-49,共5页

摘　　要： 采用多顶砧静态高温高压实验装置和X射线衍射分析方法研究了合成霞石NaAlSiO4在压力为22～25GPa,温度为1200～2000℃条件下的相变及其产物的晶体学特征,结合前人研究成果探讨了NaAlSiO4的高温高压相变过程和CaFe2O4型NaAlSiO4的稳定性及其地质意义。结果表明,合成霞石NaAlSiO4在23GPa,1500℃时就可以完全转变为CaFe2O4型NaAlSiO4。结合前人的研究成果可以认为:CaFe2O4型NaAlSiO4在地幔深部可以稳定地存在,并对Na、Al在深部的赋存具有重要意义;随着温度压力条件的变化,CaFe2O4型NaAlSiO4的晶体学参数(晶格常数、晶胞体积和计算密度)发生变化,但变化的幅度不大。 Multi-anvil apparatus and X-ray diffraction technology were used to investigate the phase transformation of synthesized NaAlSiO_(4) over a temperature range from 1200 to 2000 ℃ and a pressure range from 22 to 25 GPa. The crystal characters of transformation products were also described. The stability and implications of NaAlSiO_(4) with the calcium-ferrite type structure were discussed in combination with some other results.Analyses of quenched run products revealed that the nepheline was completely transformed into NaAlSiO_(4)with the calcium-ferrite-type structure at 23 GPa and 1500 ℃. In combination with previous results, the calcium-ferrite-type NaAlSiO_(4) can exit under the conditions of deep lower mantle and it may be the important host phase for sodium and aluminium in the deep lower mantle. With the change of temperature and pressure, the crystal parameters will change, though the ranges are limited.

关 键 词： 高温高压相变 射线衍射 晶体学参数 晶格常数 晶胞体积 计算密度 地幔

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]