Weakening of quartz rocks at subseismic slip rates due to frictional heating, but not to lubrication by wear materials of hydrated amorphous silica or silica gel
Weakening of quartz rocks at subseismic slip rates due to frictional heating, but not to lubrication by wear materials of hydrated amorphous silica or silica gel
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由于摩擦加热，石英岩在次震滑移率下被削弱，但不是由于水合无定形二氧化硅或硅胶磨损材料的润滑
DOI：
10.1016/j.tecto.2020.228429
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发表时间：
2020
期刊：
影响因子：
2.9
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Kanagawa;K.;Murayama;H.;Sugita;A.;Takahashi;M.;Sawai;M.;Furukawa;N. and Hirose;T.
为了阐明次震滑动速率在0.1~10 cm/S范围内石英岩的弱化机制，我们进行了两个系列的旋转剪切摩擦实验：一个是完整玛瑙控制背景温度和大气的实验，另一个是完整玛瑙和靠近滑动面或泥层的硅胶监测温度(T)的实验。在前一次实验中，在Veq=1110 cm/S的情况下，无论潮湿或干燥条件下，室温下玛瑙的稳态摩擦系数都相似(μss=0.62-0.63)，后者阻碍了非晶态磨损材料的水化；而在TBG=1100℃时，玛瑙样品表现出减弱到μss≈=0.35的趋势。在后一次实验中，完整玛瑙和硅胶泥的μSSOF均随Veq的增大而减小，从Veq=0.10 cm/S的0.6-0.7at Veq降至0.03-0.16at Veq=10.10 cm/S，而最大值T则随Veq的增大而增大，从Veq=90.1 cm/S的Veq为25-28°C，到Veq=10.10 cm/S时的88-93°C。这两组摩擦实验表明，石英岩在亚震滑动速率下的摩擦强度受温度控制，温度随摩擦加热而增加，但不受水化无定形二氧化硅或硅胶磨损材料的影响。石英岩的压痕强度远高于其他常见造岩矿物，因此在石英岩的粗糙接触处产生的摩擦热比其他岩石多得多，这可能是导致石英岩在亚震滑动速率下变弱的原因。
In order to clarify the weakening mechanism of quartz rocks at subseismic slip rates of 0.1–10 cm/s, we conducted two series of rotary-shear friction experiments at a normal stress of 1.5 MPa and equivalent slip rates (Veq) of 0.1–10 cm/s; one on intact agate controlling background temperature (TBG) and atmosphere, and the other on intact agate and silica-gel gouge monitoring temperature (T) adjacent to the slip surface or the gouge layer. In the former experiments atVeq= 1 cm/s, agate samples at roomTBGshowed similar steady-state friction coefficients (μss= 0.62–0.63) irrespective of humid or dry condition in the latter case of which hydration of amorphous wear materials was hampered, while agate sample atTBG= 100 °C exhibited weakening toμss≈ 0.35. In the latter experiments,μssof both intact agate and silica-gel gouge decreased with increasingVeqfrom 0.6–0.7 atVeq= 0.1 cm/s to 0.03–0.16 atVeq= 10 cm/s, while the maximumTincreased with increasingVeqfrom 25–28 °C atVeq= 0.1 cm/s to 88–93 °C atVeq= 10 cm/s. Spikes of high friction followed byTmaxima and subsequent weakening suggest that slip at strong asperity contacts induced frictional heat, which in turn resulted in weakening. These two series of friction experiments indicate that the frictional strength of quartz rocks at subseismic slip rates is controlled by temperature, which increases by frictional heating, but not by wear materials of hydrated amorphous silica or silica gel. Indentation strength of quartz is much higher than that of other common rock-forming minerals so that much more amount of frictional heat would be induced at asperity contacts in quartz rocks than in other rocks, which is likely responsible for weakening of quartz rocks at subseismic slip rates.
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影响因子：
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作者：
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通讯作者：
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DOI：
10.5575/geosoc.102.240
发表时间：
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