High temperature deformation experiment on iron rich olivine.

利用高精度Paterson气体介质变形装置对(Mg0.5,Fe0.5)2SiO4和(Mg0.7,Fe0.3)2SiO4橄榄石集合体进行了高温三轴压缩变形试验。首先用人工合成了纯铁橄榄石Fe2SiO4,然后用合成的纯铁橄榄石与天然圣卡罗橄榄石按一定比例混合烧结合成了含铁量分别为50％和30％的富铁橄榄石集合体Fo50和Fo70。三轴压缩蠕变变形试验在温度1223-1473 K和围压 300 MPa的条件下进行,差应力为10-300 MPa,应变率为10-7-10-4s-1,每个试件的最大变形量为20％．利用三维非线性方法对蠕变数据进行拟合,得出的流动律中,Fo50应力指数为4．1,活化能为499...Triaxial compressive creep experiments were performed on fine-grained Fe rich olivine samples of ( Mg-0.5 Fe-0.5)(2) SiO4 and (Mg0.7Fe0.1)(2)SiO4. Firstly, the fayalite, Fe2SiO4 powder was synthesized in one atmosphere furnace from high-purily oxides. Then, the (Mg-0.5,Mg- Fe-0.5)(2) SiO4 and ( Mg-0.7 Fe-0.3)(2) SiO4 samples were fabricated from a mixture of powders of San Carlos olivine, (Mg-0.9 Fe-0.1)(2) SiO4, and synthetic fayalite, Fe2SiO4. Samples were deformed in a gas-medium apparatus at a temperature of 1223 1473 K and a confining pressure of 300 MPa. Differential stresses in the range from 10 to 300 MPa resulted in strain rates between 10(-7) similar to 10(-4)s(-1). The samples were deformed both in diffusion creep and dislocation creep regimes. From the three dimensional global non-linear fitting of the test data, the stress exponent for Fo(50) and Fo(70) were determined as 4. 1 and 4. 3, respectively., and the activation energy for Fo(50) and Fo(70) as 499kJ/mol and 510kJ/mol, respectively. These Fo(50) samples creep at a rate over a factor of 10 faster than similar samples of Fo(70) and Fo(70) samples creep at a rate over a factor of 10 faster than those of Fo(90) deformed under the same conditions. Therefore, this paper gives a preliminary test result of effect of iron content on the viscosity of olivine aggregates.SCI(E)中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)503999-10042