摘要
通过高温高压实验研究了铁橄榄石集合体的流变性。首先,利用高精度的Paterson气体介质变形装置对铁橄榄石集合体Fe_2SiO_4进行了高温三轴压缩蠕变试验。变形试验条件为:温度1273～1423K,围压300MPa,差应力10～250MPa,应变率10^(-7)～10^(-4)s^(-1),试件的最大变形量不超过20%。利用三维非线性拟合方法对蠕变试验数据进行分析,得到铁橄榄石集合体的微观变形机制为扩散域和位错域,扩散域的应力指数为1左右。位错蠕变域中,干燥铁橄榄石集合体的应力指数为5.4,活化能为781kJ/mol;含水铁橄榄石集合体的应力指数为3.4,活化能为516kJ/mol。实验结果表明,含水时铁橄榄石的流变强度比干燥时小一个数量级。将实验结果与铁橄榄石单晶的强度进行对比,发现铁橄榄石集合体的流变强度比铁橄榄石单晶的强度高。从而得到了铁橄榄石集合体高温高压流变性(强度)的初步试验结果。
The high temperature and high pressure rheology of fayalite olivine was studied in this paper.Tri-axial compressive creep experiments were performed on anhydrous as well as hydrous fine-grained fayalite olivine samples.Samples were deformed in a gas-medium apparatus at a confining pressure of 300MPa,a temperature between 1273 and 1423K,a differential stress 10～250MPa, a strain rate 10^(-7)～10^(-4)s^(-1),and the maximum accumulative strain 20%,respectively,for each sample.The samples were deformed both in the diffusion and the dislocation creep regime.From three dimensional global non-linear fitting of the test data,the stress exponent was determined as 5.4 for anhydrous fayalite olivine and 3.4 for hydrous fayalite olivine samples in dislocation creep regime, respectively,and the activation energy is 781kJ/mol for dry fayalite and 516kJ/mol for wet fayalite olivine samples,respectively. These hydrous samples creep at a rate over a factor of 10 faster than those anhydrous samples under the same deformation conditions. Therefore,this paper gives a preliminary test result of effect of temperature and water on the viscosity of fayalite olivine aggregates.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第11期2927-2932,共6页
Acta Petrologica Sinica
基金
国家自然科学基金项目(40174028
40474035
40521002)资助.
关键词
铁橄榄石
粘性
高温蠕变
三轴压缩
实验研究
Fayalite olivine
Viscosity
High temperature creep
Three dimensional compression
Experimental study
