Pressure-related feedback processes in the generation of pseudotachylytes
Pressure-related feedback processes in the generation of pseudotachylytes
复制标题
假速水剂生成过程中与压力相关的反馈过程
DOI：
10.1016/j.jsg.2002.08.001
复制
发表时间：
2004
影响因子：
3.1
通讯作者：
J. F. Magloughlin
中科院分区：
文献类型：
--
作者：
M. Bjornerud;J. F. Magloughlin
伪羧酸盐的形成通常被视为一个自我限制的过程。定量模型已经证明，在地震滑动率下，摩擦熔化是可能的，但是一旦在地震断层面上形成一层薄薄的熔体膜，断层摩擦的急剧减少被认为会抑制进一步的熔化。然而，在实地研究中观察到的熔体产生的伪酸碱的体积在许多情况下比理论模型预测的摩擦熔体的数量大得多。这表明以前未被认识到的物理过程可能会在地震滑动期间加强融化。局部减压在扩张慢跑可能是这样一种现象。暂态卸荷在假羧酸盐生成动力学中起着两个重要作用。首先，通过建立显著的流体压力梯度，将导致熔体快速迁移到低压部位，从而重建断层表面的摩擦接触，有利于熔体的进一步产生。其次，在显著深度，突然降压可能导致就地减压熔化。
Pseudotachylyte formation is typically viewed as a self-limiting process. Quantitative models have demonstrated that frictional melting is possible at seismic slip rates, but once a thin film of melt forms on a seismic fault plane, the dramatic decrease in fault friction is thought to suppress further melting. Volumes of melt-generated pseudotachylyte observed in field studies, however, are in many cases substantially larger than the amounts of frictional melt predicted by theoretical models. This suggests that previously unrecognized physical processes may enhance melting during seismic slip. Localized decompression at dilational jogs may be one such phenomenon. Transient unloading could play two important roles in the dynamics of pseudotachylyte generation. First, by setting up significant fluid pressure gradients, it would lead to rapid migration of the melt to sites of low pressure, thereby reestablishing frictional contact across the fault surface and favoring further melt generation. Second, at significant depths, sudden depressurization might lead to in situ decompression melting.