Importance of pressure solution and coble creep in the deformation of polymineralic rocks
Importance of pressure solution and coble creep in the deformation of polymineralic rocks
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压溶和铜缆蠕变在多矿物岩变形中的重要性
DOI：
10.1029/91jb02476
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发表时间：
1992
影响因子：
--
通讯作者：
J. Wheeler
中科院分区：
文献类型：
--
作者：
J. Wheeler
提出了模拟多相岩石压力解的理论框架。通常认为压力溶解是岩石圈深部次要的变形机制。研究表明，相对于单矿物岩石，双矿物和多矿物岩石在压力溶解期间的流变性可能会急剧降低，因此这种变形机制的重要性可能被低估了。这种行为与经历位错蠕变的多矿物岩石的行为形成对比，现有模型表明流变学将是各个相的流变学的某种平均值。例如，纯橄榄岩在压力溶液中的流变性受MgO和SiO2的扩散控制;无论哪个最慢，都会控制岩石的粘度。相反，在具有特定结构的哈兹伯岩中，流动将由扩散最快的物质控制;因此，其强度可能与粒度相当的石英岩一样低。考虑到相对于石英进行位错蠕变的许多阶段的比较强度，这一预测意味着更大范围的条件下，压力解决方案形成的一个重要组成部分，散装岩石变形比以前推断。预测了多矿物集合体的结构演化，结果表明，在变形过程中，某些矿物颗粒可能会平行于最大主应力方向伸长，即使岩石作为一个整体在这个方向缩短。
The theoretical framework for modeling pressure solution in polyphase rocks is presented. It is often assumed that pressure solution is a deformation mechanism of secondary importance deep in the lithosphere. It is shown here that the rheology of rock during pressure solution may be drastically reduced in a bimineralic and polymineralic rock relative to its monomineralic counterparts, and therefore the importance of this deformation mechanism importance is perhaps underestimated. This behavior contrasts with that of a polymineralic rock undergoing dislocation creep, where existing models show that the rheology will be some average of the rheologies of individual phases. For instance, the rheology of a dunite in pressure solution is governed by the diffusion of both MgO and SiO2; whichever is the slowest will control the viscosity of the rock. Conversely, in a harzburgite with a specific texture, flow will be governed by the fastest diffusing species; thus its strength may be as low as that of a quartz rock of comparable grain size. Given the comparative strength of many phases undergoing dislocation creep relative to quartz, this prediction implies a larger range of conditions under which pressure solution forms an important part of bulk rock deformation than inferred previously. Predictions on textural evolution of polymineralic aggregates are also made, and it is shown that some minerals grains may become elongate parallel to the maximum principal stress during deformation, even though the rock as a a whole shortens in this direction.