期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
卷 113, 期 B6, 页码 -出版社
AMER GEOPHYSICAL UNION
DOI: 10.1029/2007JB005039
关键词
-
The healing of fault gouge was studied by examining microstructures of naturally and experimentally produced granitoid fault rock. We performed deformation experiments on intact granitoid rock samples at T = 300 - 500 degrees C, P-c = 500 MPa, and (epsilon) over dot = 1.2x 10(4) - 1.3 x 10(-7) s(-1) with 0.2 wt% H2O added. Healing experiments were carried out on deformed samples at T = 200-500 degrees C, P-c = 500 MPa, for 4 h to 14 days under hydrostatic and nonhydrostatic conditions. The grain size distributions ( GSD) of the deformed samples were quantified using the D-> value ( slope of log( frequency) - log( radius) of the GSD) for quartz and feldspar fault gouge. Healing causes a decrease in the D-> value from > 2.0 to similar to 1.5. The time dependence of the D-> decrease is described by a hydrostatic healing law of the form Delta D = D->( t) - D-f = A . e( -lambda.t). The results of the laboratory experiments were compared to three natural fault systems, ( 1) Nojima Fault Zone ( Japan), ( 2) fault zones in the Black Forest ( Germany), and ( 3) Orobic Thrust ( Italian Alps). Natural and experimental gouges have similar D-> values. Healing is only observed in monomineralic aggregates; polymineralic ( i. e., mixed) fault gouges retain their high D-> value after extended healing times because grain growth is inhibited. Healing under nonhydrostatic conditions is more rapid than hydrostatic healing. The low strain rates, which were measured during nonhydrostatic healing, are temperature-dependent and suggest that diffusive mass transfer processes take place during deformation. Thus, fault rocks at upper to midcrustal depth may deform by combined cataclasis and diffusive mass transfer.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据