Frictional constitutive behavior of chlorite at low shearing rates and hydrothermal conditions
Frictional constitutive behavior of chlorite at low shearing rates and hydrothermal conditions
复制标题
低剪切速率和水热条件下绿泥石的摩擦本构行为
DOI：
10.1016/j.tecto.2022.229435
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发表时间：
2022
期刊：
影响因子：
2.9
通讯作者：
French, Melodie E.
中科院分区：
文献类型：
--
作者：
Belzer, Benjamin D.;French, Melodie E.
绿泥石是沿大陆和俯冲带断层分布的一种常见但尚未得到充分研究的页硅酸盐矿物。为了了解绿泥石在不同断层滑动模式中的潜在作用，我们通过在三轴锯切配置中剪切水饱和绿泥石粉末样品来测量绿泥石在低变形率和浅水热条件下的本构摩擦特性。实验在 25 至 130 °C、130 MPa 围压、10 MPa 至 120 MPa 孔隙压力、0.001 至 10 μm/s 滑移速率以及高达 7.5 mm 的剪切位移下进行。亚氯酸盐的摩擦强度随着温度从 25°C 升高到 130°C（μ=0.4 到 0.46）而增加，同时 Riedel 剪切力也随之增加。绿泥石还会从快滑移速率（0.1 至 10 μm/s）下的速率强化行为转变为较低滑移速率（0.001 至 0.01 μm/s）下的速率减弱或速率中性行为，这与慢滑移原因的一种假设一致。摩擦行为的这种转变反映了控制摩擦的直接效应和演化效应的不同微观物理过程。在低变形率下，直接效应 (a) 的大小和温度敏感性与亚临界断裂一致。相反，演化效应 (b) 对温度不敏感，并且随着应变率的降低而系统地增加。我们提出带内增加导致绿泥石速率减弱行为随着滑移率的降低而增加，这是由矿物表面吸附水的时间依赖性特性控制的。
Chlorite is a common, but understudied phyllosilicate mineral along continental and subduction zone faults. To understand the potential role of chlorite in different modes of fault slip, we measure the constitutive frictional properties of chlorite at low rates of deformation and shallow hydrothermal conditions by shearing powdered samples of water-saturated chlorite in the triaxial saw-cut configuration. Experiments were conducted at 25 to 130 °C, 130 MPa confining pressure, pore pressures from 10 MPa to 120 MPa, slip rates from 0.001 to 10 μm/s, and shear displacements up to 7.5 mm. The frictional strength of chlorite increases with increasing temperature from 25 to 130 °C (μ = 0.4 to 0.46), accompanied by an increased abundance of Riedel shears. Chlorite also transitions from rate-strengthening behavior at fast slip rates (0.1 to 10 μm/s) to rate-weakening or rate-neutral behavior at lower slip rates (0.001 to 0.01 μm/s), consistent with one hypothesis for the cause of slow slip. This transition in frictional behavior reflects different microphysical processes controlling the direct and evolution effects of friction. At low deformation rates, the magnitude and temperature sensitivity of the direct effect (a) are consistent with subcritical fracture. In contrast, the evolution effect (b) is insensitive to temperature and increases systematically with decreasing strain rate. We propose the increase inband resulting rate-weakening behavior of chlorite with decreasing slip rate is controlled by time-dependent properties of adsorbed water to mineral surfaces.