Nanocrystalline Principal Slip Zones and Their Role in Controlling Crustal Fault Rheology
Nanocrystalline Principal Slip Zones and Their Role in Controlling Crustal Fault Rheology
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DOI：
10.3390/min9060328
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发表时间：
2019-05
期刊：
影响因子：
2.5
通讯作者：
B. Verberne;O. Plümper;C. Spiers
中科院分区：
文献类型：
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作者：
B. Verberne;O. Plümper;C. Spiers
主滑动带（PSZ）是发生在上地壳断裂带核部的局部剪切变形的狭窄（<10 cm）带，在那里它们容纳了大部分的断层位移。天然的和实验形成的PSZ一致地显示出在<100 nm尺寸范围内的纳米微晶的存在。尽管这种纳米晶体（NC）断层岩在控制断层力学行为方面的重要性，但它们在控制自然地震周期方面的普遍性和潜在作用仍然没有得到充分的研究。在这篇文章中，我们总结了NC材料的物理性质，可能有一个深刻的影响，断层流变学，我们回顾了自然断层和实验中观察到的NC PSZ的结构特征。大量的文献报道表明，这种带形成于各种各样的断层岩石类型中，在与地震和非地震上地壳断层滑动有关的各种条件下，并且经常显示出内部晶体学优选取向（CPO）和部分非晶化，以及形成光滑的或“镜面”滑动面。鉴于NC PSZ在上地壳断裂中的广泛存在，我们认为它们具有普遍意义。具体而言，NC断层岩中普遍较高的（扩散）蠕变速率可能在控制孕震区的深度限制方面发挥关键作用。
Principal slip zones (PSZs) are narrow (<10 cm) bands of localized shear deformation that occur in the cores of upper-crustal fault zones where they accommodate the bulk of fault displacement. Natural and experimentally-formed PSZs consistently show the presence of nanocrystallites in the <100 nm size range. Despite the presumed importance of such nanocrystalline (NC) fault rock in controlling fault mechanical behavior, their prevalence and potential role in controlling natural earthquake cycles remains insufficiently investigated. In this contribution, we summarize the physical properties of NC materials that may have a profound effect on fault rheology, and we review the structural characteristics of NC PSZs observed in natural faults and in experiments. Numerous literature reports show that such zones form in a wide range of faulted rock types, under a wide range of conditions pertaining to seismic and a-seismic upper-crustal fault slip, and frequently show an internal crystallographic preferred orientation (CPO) and partial amorphization, as well as forming glossy or “mirror-like” slip surfaces. Given the widespread occurrence of NC PSZs in upper-crustal faults, we suggest that they are of general significance. Specifically, the generally high rates of (diffusion) creep in NC fault rock may play a key role in controlling the depth limits to the seismogenic zone.