A physical basis for the frictional melting of some rock-forming minerals
A physical basis for the frictional melting of some rock-forming minerals
复制标题
DOI：
10.1016/0040-1951(92)90308-s
复制
发表时间：
1992-04
期刊：
影响因子：
2.9
通讯作者：
J. Spray
中科院分区：
文献类型：
--
作者：
J. Spray
在上地壳同震滑动（0.1-2.0 m s-1）的条件下，岩石矿物的剪切屈服强度、断裂韧性、熔点以及较小程度上的热导率的差异导致摩擦熔融能力的等级。在许多所谓的假玄武玻璃中，可以观察到层状硅酸盐和角闪石优先被消耗以形成熔融相，而石英和长石倾向于作为碎屑存活下来。这可以用具有较低剪切屈服强度、断裂韧性和热导率的那些矿物相的不平衡“闪”熔来解释，而不是通过共晶熔融来解释，否则共晶熔融将产生指示火成岩过程的平衡最小熔融。在高应变率典型的同震断层，矿物的力学行为主要是由其断裂韧性，与渐进的粉碎过程中滑动导致融合控制。摩擦熔融对矿物力学性质的依赖性表明，如果摩擦熔融导致断层润滑，则围岩岩性与地震震级之间可能存在重要关系。
Under conditions of coseismic slip (0.1–2.0 m s−1) within the upper crust, differences in the shear yield strengths, fracture toughnesses, melting points and, to a lesser extent, thermal conductivities of rock-forming minerals result in a hierarchy of friction melting susceptibilities. In many so-called pseudotachylytes it is observed that phyllosilicates and amphiboles are preferentially consumed to form the melt phase, whilst quartz and feldspar tend to survive as clasts. This can be explained in terms of the disequilibrium “flash” melting of those mineral phases possessing the lower shear yield strengths, fracture toughnesses and thermal conductivities rather than by eutectic melting that would otherwise generate equilibrium minimum melts indicative of igneous processes. At high strain rates typical of coseismic faulting, the mechanical behaviour of minerals is primarily controlled by their fracture toughnesses, with progressive comminution during slip leading to fusion. The friction melting dependence on the mechanical properties of minerals indicates that there may be an important relationship between wall-rock lithology and earthquake magnitude if frictional melting results in fault lubrication.