Effect of grain size on the distribution and transport of deep‐seated fluids and melts
Effect of grain size on the distribution and transport of deep‐seated fluids and melts
复制标题
晶粒尺寸对深层流体和熔体分布和输运的影响
DOI：
--
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
E. Watson
中科院分区：
文献类型：
--
作者：
D. Wark;E. Watson
由于对于给定的流体分数，渗透率随粒度的平方而增加，因此通常认为流体和熔体的多孔流动在深部岩石的粗粒区域中更有效。然而，这种相对行为是准确的，只是作为两个系统孤立运行的描述。我们证明，如果粗晶粒和细晶粒域是化学通信，那么整个系统的孔壁曲率的均衡导致流体或熔体在更细晶粒尺寸的域中的浓度。由于流体的这种局部化，较细颗粒域的渗透率将匹配或超过具有较粗颗粒的域的渗透率。由于颗粒大小的差异而引起的流体聚集对变质流体的颗粒尺度输运具有潜在的重要意义-包括从俯冲板片释放到剪切地幔楔中的流体-以及地幔和地壳深部的部分熔融。
Because permeability increases with the square of the grain size for a given fluid fraction, it is commonly assumed that porous flow of fluids and melts is more effective in coarse‐grained domains of deep‐seated rocks. This relative behavior is accurate, however, only as a description of two systems operating in isolation. We demonstrate that if coarse‐ and fine‐grained domains are in chemical communication, then equilization of pore‐wall curvature across the system results in concentration of fluid or melt in domains of finer grain size. Because of this localization of fluid, the permeability of the finer‐grained domains will match or exceed that of domains with coarser grains. Fluid focussing due to differences in grain size has potentially important implications for grain‐scale transport of metamorphic fluids — including those released from subducting slabs into the sheared mantle wedge — and also for partial melts in the mantle and deep crust.