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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499kJ／mol;Fo70应力指数为4．3,活化能为510kJ／ mol。将实验结果与Fo90圣卡罗橄榄石集合体的强度进行对比,发现含铁量的增加使橄榄石的强度明显下降,Fo50橄榄石集合体比Fo70的粘性低一个量级,Fo70比Fo90的粘性低一个量级。从而得到了含铁量对橄榄石的粘性(强度)影响的初步试验结果。
High-temperature triaxial compression deformation tests were carried out on (Mg0.5, Fe0.5) 2SiO4 and (Mg0.7, Fe0.3) 2SiO4 olivine aggregates using a Paterson gas medium deformation device. Firstly, pure Fe-peridotite Fe2SiO4 was synthetically synthesized, and then the Fe-rich olivine aggregate with the iron content of 50% and 30% was synthesized by mixing the pure Fe-peridot and the natural sa-Carlot olivine Fo50 and Fo70. The triaxial compression creep deformation test was carried out at a temperature of 1223-1473 K and a confining pressure of 300 MPa with a differential stress of 10-300 MPa and a strain rate of 10-7-10-4 s-1, with the maximum per specimen Deformation is 20%. The three-dimensional nonlinear method was used to fit the creep data. The Fo50 stress exponent was 4.1, the activation energy was 499kJ / mol, the Fo70 stress index was 4.3, and the activation energy was 510kJ / mol. Comparing the experimental results with the strength of Fo90 San Carlo olivine aggregate, it is found that the increase of iron content significantly decreases the strength of olivine, the Fo50 olivine aggregate is one order of magnitude less viscous than Fo70, and Fo70 is more viscous than Fo90 One order of magnitude lower. The preliminary test results of the influence of iron content on the viscosity (strength) of olivine were obtained.