Trace element anomaly in fault rock induced by coseismic hydrothermal reactions reproduced in laboratory friction experiments
Trace element anomaly in fault rock induced by coseismic hydrothermal reactions reproduced in laboratory friction experiments
复制标题
DOI：
10.1002/2015gl063195
复制
发表时间：
2015-05
影响因子：
5.2
通讯作者：
W. Tanikawa;T. Ishikawa;G. Honda;T. Hirono;O. Tadai
中科院分区：
文献类型：
--
作者：
W. Tanikawa;T. Ishikawa;G. Honda;T. Hirono;O. Tadai
在室温和高孔隙流体压力（2或5 MPa）下，对取自台湾车笼埔断层的模拟断层泥进行了高速（0.1 ~ 0.4m/s）摩擦实验和微量元素分析。滑动过程中摩擦系数降至~0.1，滑动位移6 m时滑动面温度达到300°C。当滑动面温度超过300°C时，滑动导致变形断层泥中Li的少量但明显的减少。观察到的Li消耗与计算结果一致，表明其是由短时间（高达40 s）摩擦加热产生的高温下的水热反应引起的。地球化学数据表明，模拟断层中的流体/岩石比较小，反应温度较低，这可以通过较高的正应力或重复地震来解释，这些地震提高了天然断层中的流体-岩石比。
Friction experiments at high velocities (0.1 to 0.4 m/s) at room temperature under high pore fluid pressures (2 or 5 MPa) and trace element analyses of the run products were carried out on simulated fault gouge derived from the Chelungpu fault, Taiwan. The friction coefficient decreased to ~0.1 during sliding, and the slip surface temperature reached 300°C by 6 m of slip displacement. The slip caused a small, but distinct decrease of Li in the deformed gouge when the slip surface temperature exceeded 300°C. The observed Li depletion agreed with calculated results, indicating that it resulted from a hydrothermal reaction at a high temperature produced by short‐duration (up to 40 s) frictional heating. The geochemical data suggest a small fluid/rock ratio and low reaction temperature in the simulated fault, which is explained by higher normal stress or repeated earthquakes which elevated fluid‐rock ratios in the natural fault.