摘要
采用多顶砧高压实验装置研究了Mg_2SiO_4-MgAl_2O_4体系在压力为22 GPa,温度为1550～1750 ℃条件下的相变,并考查了Al_2O_3在γ相中的固溶度。结果表明,随着体系中MgAl_2O_4组分含量的增加,相组合发生了变化,依次为γ相+镁铝硅酸盐固溶体+方镁石→镁铝硅酸盐固溶体+方镁石→镁铝硅酸盐固溶体+方镁石+刚玉固溶体;镁铝硅酸盐固溶体具有石榴子石结构,其化学成分随着体系中共存相的改变而有所变化;Al_2O_3在γ相中的固溶度很低(其重量百分比<0.8％),因此,在Mg_2SiO_4-MgAl_2O_4体系中Al_2O_3可能对γ相超尖晶石分解转变的压力不会有很大的影响。
High-pressure and high-temperature experiments were conducted on the system Mg2SiO4-MgAl2O4 over a temperature range from 1550 to 1750℃ at 22 GPa with a multi-anvil apparatus. Analyses of quenched run products revealed that in the present system, with the MgAl2O4 component increasing, the phase assemblages change from y phase to 7 phase + majorite + MgO, and to majorite + MgO, and to majorite + MgO + corundum solid solution, and finally to MgO + Al2O3 oxide mixture in the MgAl2O4 end-member. The majorite solid solution has the garnet structure and its composition varies, depending on the coexisting phases. The Al2O3 content of the γ phase is very low (-0.8wt%), so the Al2O3 content of the Mg2SiO4-MgAl2O4 system may not significantly affect the phase boundary of the post-spinel transformation because of very limited Al2O3 solubility in Mg2SiO4-spinel.
出处
《矿物学报》
CAS
CSCD
北大核心
2003年第3期267-272,共6页
Acta Mineralogica Sinica
基金
国家自然科学基金(批准号:49872073
40072096)
教育部高等学校优秀青年教师教学和科研奖励计划
美国国家科学基金(EAR-9873577)
美国Camegie Institution Washington资助项目
