Abstract Amorphous materials are frequently observed in natural and experimentally produced fault rocks. Their common occurrence suggests that amorphous materials are of importance to fault zone dynamics. However, little is known about the physico-chemical impact of amorphous materials on fault rheology. Here we present deformation experiments on mafic fault rock, where amorphous material forms due to intense mechanical wear during the experiments. The experiments are run at temperatures from 300 to 600 °C, confining pressures of 0.5 or 1.0 GPa, and at constant displacement rates of ( d ˙ ax) 2 ·10−7, 2 ·10−8 or 2 ·10−9 ms−1, resulting in bulk strain rates ( γ ˙ ) of ≈3 ·10−4, 3 ·10−5 and 3 ·10−6 s−1. At these conditions, the mafic rock material undergoes intense brittle deformation and cataclastic flow, but sample strength significantly decreases with increasing temperatures – a feature commonly attributed to viscous deformation processes. Microstructural analyses show that after an initial stage of homogeneous cataclastic flow, strain localizes into narrow (2–10 μm wide) ultra-cataclastic bands that evolve into amorphous shear bands. With the data presented in this research paper, we argue that the temperature sensitivity recorded in the mechanical data is caused by viscous deformation of the amorphous material. We suggest that with the formation of amorphous materials during brittle deformation, fault rheology becomes significantly temperature-sensitive. This has important implications for our understanding of fault strength and weakening due to the presence of amorphous materials. In addition, weak material along faults will lead to stress concentrations that may trigger seismic rupture.

中文翻译：

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实验变形基性岩中的非晶材料及其温度依赖性：对抗震蠕变和地震破裂过程中断层流变学的影响

摘要 在天然和实验产生的断层岩中经常观察到无定形物质。它们的普遍现象表明非晶材料对断层带动力学很重要。然而，关于非晶材料对断层流变学的物理化学影响知之甚少。在这里，我们展示了镁铁质断层岩的变形实验，在实验过程中，由于强烈的机械磨损，形成了无定形材料。实验在 300 至 600 °C 的温度、0.5 或 1.0 GPa 的围压以及 (d·ax) 2·10-7、2·10-8 或 2·10-9 ms 的恒定位移速率下进行−1，导致体应变率 ( γ ˙ ) ≈3 ·10−4、3 ·10−5 和 3 ·10−6 s−1。在这些条件下，基性岩石材料经历剧烈的脆性变形和碎裂流，但样品强度随着温度的升高而显着降低——这一特征通常归因于粘性变形过程。微观结构分析表明，在均匀碎裂流的初始阶段之后，应变局部化为狭窄的（2-10 μm 宽）超碎裂带，然后演变为无定形剪切带。根据本研究论文中提供的数据，我们认为机械数据中记录的温度敏感性是由非晶材料的粘性变形引起的。我们认为，随着脆性变形过程中非晶材料的形成，断层流变学变得对温度非常敏感。由于非晶材料的存在，这对我们理解断层强度和弱化具有重要意义。此外，