Optically Stimulated Luminescence Signal Resetting of Quartz Gouge During Subseismic to Seismic Frictional Sliding: A Case Study Using Granite‐Derived Quartz
Optically Stimulated Luminescence Signal Resetting of Quartz Gouge During Subseismic to Seismic Frictional Sliding: A Case Study Using Granite‐Derived Quartz
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次震到地震摩擦滑动过程中石英凿的光激发光信号重置：使用花岗岩衍生石英的案例研究
DOI：
10.1029/2020jb019900
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Kazumasa Miura
中科院分区：
文献类型：
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作者：
Kiyokazu Oohashi;Yuki Minomo;Koji Akasegawa;Noriko Hasebe;Kazumasa Miura
人们尝试使用 K-Ar、裂变径迹、电子自旋共振和发光测年方法来确定断层岩记录的断层年龄。在这里，我们报告了摩擦实验后石英泥光激发光（OSL）信号的明确减少（重置），并估计了自然断层带中 OSL 信号重置所需的地震和地质条件。实验中，我们使用粒径<150μm的石英砂，等效剂量为31.5±16.6Gy。使用旋转剪切高速摩擦装置进行摩擦实验，滑移率 (V) 为 200 μm s−1 至 1.3 m s−1，法向应力为 1.0 MPa，位移为 10 m。在干燥条件下进行的实验中，OSL 信号从 V= 0.25 m s−1 开始下降，并在 V≥ 0.65 m s−1 时变得接近于零。在加水条件下以 1.3 m s−1 剪切的实验中也观察到 OSL 信号重置。 AtV= 0.25 和 0.40 m s−1 时，发生部分重置，其特征是具有和不具有 OSL 信号的粒子共存。 OSL 信号强度与高速摩擦过程中施加的功率密度和摩擦热具有很强的相关性，并且信号随着功率密度和温度的增加呈指数下降。部分和完全 OSL 信号重置所需的功率密度分别为 ~0.17 和 0.6 MW m−2。假设同震断层滑移率为 0.6 m s−1，部分和完全复位所需的深度预计分别为 ≥11 和 ≥42 m。
Attempts to determine the age of faulting recorded by fault rocks have been made using K–Ar, fission‐track, electron spin resonance, and luminescence dating methods. Here we report the unambiguous reduction (resetting) of optically stimulated luminescence (OSL) signals of quartz gouge after friction experiments and estimate the seismological and geological conditions required for OSL signal resetting in natural fault zones. In the experiments, we used quartz sand with a particle size of <150 μm and equivalent dose of 31.5 ± 16.6 Gy. Friction experiments were conducted with a rotary‐shear, high‐velocity friction apparatus at slip rates (V) of 200 μm s−1to 1.3 m s−1, normal stress of 1.0 MPa, and displacement of 10 m. In the experiments conducted under dry conditions, the OSL signal starts to decrease fromV= 0.25 m s−1and becomes near zero atV≥ 0.65 m s−1. OSL signal resetting is also observed in the experiment sheared at 1.3 m s−1under water‐added conditions. AtV= 0.25 and 0.40 m s−1, partial resetting occurs, which is characterized by coexistence of particles with and without an OSL signal. OSL signal intensity shows a strong correlation with applied power density and frictional heat during high‐velocity friction, and the signal exponentially decreases with increasing power density and temperature. The power density required for partial and complete OSL signal resetting is ~0.17 and 0.6 MW m−2, respectively. Assuming a co‐seismic fault slip rate of 0.6 m s−1, the depths required for partial and complete resetting are expected to be ≥11 and ≥42 m.