斜长石在下地壳温度及较低有效压力条件下的摩擦滑动
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摘要
近年来圣安德烈斯断层在下地壳深度上震颤的发现使其力学性质引起了更多的关注。文中对斜长石断层泥在低正应力条件下的摩擦滑动性质进行了实验。实验条件为有效正应力100MPa,采用围压控制,温度100~600℃,孔隙水压30MPa。通过对比有效正应力为200MPa,其他条件都相同时的实验结果发现,斜长石的摩擦滑动力学行为基本一致,仅在本构参数a值随温度的变化规律上略有差异,但在整个温度范围均呈速度弱化。由此可见,有效正应力的降低对斜长石的摩擦滑动行为影响不大,因而在下地壳可以产生不稳定滑动的结论仍然成立。
The discovery of tremors on the lower crust portion of the San Andreas Fault has attracted more attention on the mechanical properties of the lower crust in recent years,and some experimental studies have been carried out to understand the mechanical behavior. Previous experiments under effective normal stresses of 200 MPa have shown that pyroxene and plagioclase mineral separated from the gabbro and their mixtures all show velocity weakening in the lower- crust temperature range,which results in unstable slip when frictional sliding is the dominant deformation mechanism. This work is to examine whether the velocity- weakening behavior of plagioclase gouge also applies to relatively lower effective normal stress. Our experiments were performed under effective normal stress of about 100 MPa,with a constant confining pressure control,with pore pressure of 30 MPa and temperature of 100℃ to 600℃. We found that the frictional sliding of plagioclase are basically the same with the previous results obtained under effective normal stress of 200 MPa,both of which show velocity weakening over the entire temperature range. The only difference is the out-of-trend drop of constitutive parameter a at 600℃ for the lower effective normal stress of 100 MPa. It is thus concluded that reducing the effective normal stress has little effect on the sliding stability of plagioclase,and the previous conclusion made for mechanical behavior of the lower crust that unstable slips are possible therein also applies to the lower effective normal stress of 100 MPa.
The discovery of tremors on the lower crust portion of the San Andreas Fault has attracted more attention on the mechanical properties of the lower crust in recent years,and some experimental studies have been carried out to understand the mechanical behavior. Previous experiments under effective normal stresses of 200 MPa have shown that pyroxene and plagioclase mineral separated from the gabbro and their mixtures all show velocity weakening in the lower- crust temperature range,which results in unstable slip when frictional sliding is the dominant deformation mechanism. This work is to examine whether the velocity- weakening behavior of plagioclase gouge also applies to relatively lower effective normal stress. Our experiments were performed under effective normal stress of about 100 MPa,with a constant confining pressure control,with pore pressure of 30 MPa and temperature of 100℃ to 600℃. We found that the frictional sliding of plagioclase are basically the same with the previous results obtained under effective normal stress of 200 MPa,both of which show velocity weakening over the entire temperature range. The only difference is the out-of-trend drop of constitutive parameter a at 600℃ for the lower effective normal stress of 100 MPa. It is thus concluded that reducing the effective normal stress has little effect on the sliding stability of plagioclase,and the previous conclusion made for mechanical behavior of the lower crust that unstable slips are possible therein also applies to the lower effective normal stress of 100 MPa.
引文
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石耀霖,朱守彪.2003.中国大陆震源机制深度变化反映的地壳-地幔流变特征[J].地球物理学报,46(3)359-365.SHI Yao-lin,ZHU Shou-biao.2003.Contrast of rheology in the crust and mantle near Moho revealed by depth variation of earthquake mechanism in continental China[J].Chinese Journal of Geophysics,46(3):359-365(i Chinese).
韦生吉,倪四道,崇加军,等.2009.2003年8月16日赤峰地震:一个可能发生在下地壳的地震?[J].地球物理学报,52(1):111-119.WEI Sheng-ji,NI Si-dao,CHONG Jia-jun,et al.2009.The 16 August 2003 Chifeng earthquake:Is it a lower crus earthquake?[J].Chinese Journal of Geophysics,52(1):111-119(in Chinese).
杨智娴,陈运泰,郑月军,等.2003.双差地震定位法在中国中西部地区地震精确定位中的应用[J].中国科学(D辑),33(增刊):129-135.YANG Zhi-xian,CHEN Yun-tai,ZHENG Yue-jun,et al.2003.Relocation of earthquake in central-western Chin using the double difference earthquake location algorithm[J].Science in China(Series D),33(suppl):129-135(in Chinese).
臧绍先,杨军亮.1984.中国华北等地区板内地震的深度分布及其物理背景[J].地震地质,6(3):67-76.ZANG Shao-xian,YANG Jun-liang.1984.Distribution of focal depths for intraplate earthquakes in North China and physical explanation[J].Seismology and Geology,6(3):67-76(in Chinese).
曾融生,丁志峰,吴庆举,等.2000.喜马拉雅及南藏的地壳俯冲带:地震学证据[J].地球物理学报,43(6)780-797.ZENG Rong-sheng,DING Zhi-feng,ZHENG Yue-jun,et al.2003.Seismological evidence for the multiple incomplet crustal subductions in Himalaya and southern Tibet[J].Chinese Journal of Geophysics,43(6):780-797(i Chinese).
张国民,汪素云,李丽,等.2002.中国大陆地震震源深度及其构造含义[J].科学通报,47(9):663-668.ZHANG Guo-min,WANG Su-yun,LI Li,et al.2002.Focal depth of earthquakes in Chinese mainland and its tectoni implications[J].Chinese Science Bulletin,47(9):663-668(in Chinese).
Ampuero J P,Rubin A M.2008.Earthquake nucleation on rate and state faults-Aging and slip laws[J].Journal o Geophysical Research Atmospheres,113(B1):690-701.
Bai L,Ritsema J,Zhao J.2012.Focal depth estimates of earthquakes in the Himalayan-Tibetan region from teleseismic waveform modeling[J].Earthquake Sci,25(5-6):459-468.
Bayart E,Rubin A M,Marone C.2006.Evolution of fault friction following large velocity jumps[R].American Geophysical Union,Fall Meeting,abstract No.S31A-0180.
Brace W F,Byerlee J D,1966.Stick-slip as a mechanism for earthquakes[J].Science,153(3739):990-992.
Chen W P,Molnar P.1983.Focal depths of intracontinental and intraplate earthquakes and their implications for the thermal and mechanical properties of the lithosphere[J].Journal of Geophysical Research,88(B5):4183-4214.
Dieterich J H.1992.Earthquake nucleation on faults with rate-and state-dependent strength[J].Tectonophysics,211(1-4):115-134.
Gu J C,Rice J R,Ruina A L,et al.1984.Slip motion and stability of a single degree of freedom elastic system with rate and state dependent friction[J].Mech Phys Solids,32:167-196.
Gu Y,Wong T F.1994.Nonlinear dynamics of the transition from stable sliding to cyclic stick-slip in rock[M]∥Newman W I,Gabrielov A M,Turcotte D L(eds).Nonlinear Dynamics and Predictability of Geophysical Phenomena.Geophysical Monograph,83:15-35.
He C,Luo L,Hao Q,et al.,2013.Velocity-weakening behavior of plagioclase and pyroxene gouges and stabilizing effect of small amounts of quartz under hydrothermal conditions[J].Journal of Geophysical Research:Solid Earth,118(7):3408-3430.
He C,Ma S,Huang J.1998.Transition between stable sliding and stick-slip due to variation in slip rate under variable normal stress condition[J].Geophysical Research Letters,25(17):3235-3238.
He C,Wang Z,Yao W.2007.Frictional sliding of gabbro gouge under hydrothermal conditions[J].Tectonophysics,445(3-4):353-362.
He C,Yao W,Wang Z,et al.2006.Strength and stability of frictional sliding of gabbro gouge at elevated temperatures[J].Tectonophysics,427(1-4):217-229.
Lapusta N,Rice J R.2003.Nucleation and early seismic propagation of small and large events in a crustal earthquake model[J].J Geophys Res,108(B4),2205.doi:10.1029/2001JB00793.
Linker M F,Dieterich J H.1992.Effects of variable normal stress on rock friction:Observations and constitutive equations[J].Journal of Geophysical Research,97(B4):4923-4940.
Liu Y,Rice J R,2007.Spontaneous and triggered aseismic deformation transients in a subduction fault model[J].JGeophys Res,112,B09404.doi:10.1029/2007JB004930.
Liu Y,Rice J R,2009.Slow slip predictions based on granite and gabbro friction data compared to GPS measurements in northern Cascadia[J].J Geophys Res,114,B09407.doi:10.1029/2008JB006142.
Maggi A,Jackson J,McK enzie D,et al.2000a.Earthquake focal depths,effective elastic thickness,and the strength of the continental lithosphere[J].Geology,28(6):495-498.
Maggi A,Jackson J,Priestley K,et al.2000b.A reassessment of focal depth distribution in southern Iran,the Tien Shan and northern India:Do earthquakes really occur in the continental mantle?[J].Geophysical Journal International,143(3):629-661.
Nakatani M.2001.Conceptual and physical clarification of rate and state friction:Frictional sliding as a thermally activated rheology[J].Journal of Geophysical Research:Atmospheres,106(B7):13347-13380.
Rice J R,Lapusta N,Ranjith K.2001.Rate and state dependent friction and the stability of sliding between elastically deformable solids[J].Mech Phys Solids,49:1865-1898.
Ruina A.1983.Slip instability and state variable friction law[J].Journal of Geophysical Research,88(B12):10359-10370.
Tse S T,Rice J R.1986.Crustal earthquake instability in relation to the depth variation of frictional slip propertie[J].Journal of Geophysical Research:Atmospheres,91(B9):9452-9472.
Wong I G,Chapman D S.1990.Deep intraplate earthquakes in the western United States and their relationship t lithospheric temperatures[J].Bulletin of the Seismological Society of America,80(3):589-599.
罗丽,何昌荣.2009.热水条件下斜长石和辉石断层泥的摩擦滑动研究[J].地震地质,31(1):84-96.LUO Li,HE Chang-rong.2009.Frictional sliding of pyroxene and plagioclase gouges under hydrothermal condition[J].Seismology and Geology,31(1):84-96(in Chinese).
石耀霖,朱守彪.2003.中国大陆震源机制深度变化反映的地壳-地幔流变特征[J].地球物理学报,46(3)359-365.SHI Yao-lin,ZHU Shou-biao.2003.Contrast of rheology in the crust and mantle near Moho revealed by depth variation of earthquake mechanism in continental China[J].Chinese Journal of Geophysics,46(3):359-365(i Chinese).
韦生吉,倪四道,崇加军,等.2009.2003年8月16日赤峰地震:一个可能发生在下地壳的地震?[J].地球物理学报,52(1):111-119.WEI Sheng-ji,NI Si-dao,CHONG Jia-jun,et al.2009.The 16 August 2003 Chifeng earthquake:Is it a lower crus earthquake?[J].Chinese Journal of Geophysics,52(1):111-119(in Chinese).
杨智娴,陈运泰,郑月军,等.2003.双差地震定位法在中国中西部地区地震精确定位中的应用[J].中国科学(D辑),33(增刊):129-135.YANG Zhi-xian,CHEN Yun-tai,ZHENG Yue-jun,et al.2003.Relocation of earthquake in central-western Chin using the double difference earthquake location algorithm[J].Science in China(Series D),33(suppl):129-135(in Chinese).
臧绍先,杨军亮.1984.中国华北等地区板内地震的深度分布及其物理背景[J].地震地质,6(3):67-76.ZANG Shao-xian,YANG Jun-liang.1984.Distribution of focal depths for intraplate earthquakes in North China and physical explanation[J].Seismology and Geology,6(3):67-76(in Chinese).
曾融生,丁志峰,吴庆举,等.2000.喜马拉雅及南藏的地壳俯冲带:地震学证据[J].地球物理学报,43(6)780-797.ZENG Rong-sheng,DING Zhi-feng,ZHENG Yue-jun,et al.2003.Seismological evidence for the multiple incomplet crustal subductions in Himalaya and southern Tibet[J].Chinese Journal of Geophysics,43(6):780-797(i Chinese).
张国民,汪素云,李丽,等.2002.中国大陆地震震源深度及其构造含义[J].科学通报,47(9):663-668.ZHANG Guo-min,WANG Su-yun,LI Li,et al.2002.Focal depth of earthquakes in Chinese mainland and its tectoni implications[J].Chinese Science Bulletin,47(9):663-668(in Chinese).
Ampuero J P,Rubin A M.2008.Earthquake nucleation on rate and state faults-Aging and slip laws[J].Journal o Geophysical Research Atmospheres,113(B1):690-701.
Bai L,Ritsema J,Zhao J.2012.Focal depth estimates of earthquakes in the Himalayan-Tibetan region from teleseismic waveform modeling[J].Earthquake Sci,25(5-6):459-468.
Bayart E,Rubin A M,Marone C.2006.Evolution of fault friction following large velocity jumps[R].American Geophysical Union,Fall Meeting,abstract No.S31A-0180.
Brace W F,Byerlee J D,1966.Stick-slip as a mechanism for earthquakes[J].Science,153(3739):990-992.
Chen W P,Molnar P.1983.Focal depths of intracontinental and intraplate earthquakes and their implications for the thermal and mechanical properties of the lithosphere[J].Journal of Geophysical Research,88(B5):4183-4214.
Dieterich J H.1992.Earthquake nucleation on faults with rate-and state-dependent strength[J].Tectonophysics,211(1-4):115-134.
Gu J C,Rice J R,Ruina A L,et al.1984.Slip motion and stability of a single degree of freedom elastic system with rate and state dependent friction[J].Mech Phys Solids,32:167-196.
Gu Y,Wong T F.1994.Nonlinear dynamics of the transition from stable sliding to cyclic stick-slip in rock[M]∥Newman W I,Gabrielov A M,Turcotte D L(eds).Nonlinear Dynamics and Predictability of Geophysical Phenomena.Geophysical Monograph,83:15-35.
He C,Luo L,Hao Q,et al.,2013.Velocity-weakening behavior of plagioclase and pyroxene gouges and stabilizing effect of small amounts of quartz under hydrothermal conditions[J].Journal of Geophysical Research:Solid Earth,118(7):3408-3430.
He C,Ma S,Huang J.1998.Transition between stable sliding and stick-slip due to variation in slip rate under variable normal stress condition[J].Geophysical Research Letters,25(17):3235-3238.
He C,Wang Z,Yao W.2007.Frictional sliding of gabbro gouge under hydrothermal conditions[J].Tectonophysics,445(3-4):353-362.
He C,Yao W,Wang Z,et al.2006.Strength and stability of frictional sliding of gabbro gouge at elevated temperatures[J].Tectonophysics,427(1-4):217-229.
Lapusta N,Rice J R.2003.Nucleation and early seismic propagation of small and large events in a crustal earthquake model[J].J Geophys Res,108(B4),2205.doi:10.1029/2001JB00793.
Linker M F,Dieterich J H.1992.Effects of variable normal stress on rock friction:Observations and constitutive equations[J].Journal of Geophysical Research,97(B4):4923-4940.
Liu Y,Rice J R,2007.Spontaneous and triggered aseismic deformation transients in a subduction fault model[J].JGeophys Res,112,B09404.doi:10.1029/2007JB004930.
Liu Y,Rice J R,2009.Slow slip predictions based on granite and gabbro friction data compared to GPS measurements in northern Cascadia[J].J Geophys Res,114,B09407.doi:10.1029/2008JB006142.
Maggi A,Jackson J,McK enzie D,et al.2000a.Earthquake focal depths,effective elastic thickness,and the strength of the continental lithosphere[J].Geology,28(6):495-498.
Maggi A,Jackson J,Priestley K,et al.2000b.A reassessment of focal depth distribution in southern Iran,the Tien Shan and northern India:Do earthquakes really occur in the continental mantle?[J].Geophysical Journal International,143(3):629-661.
Nakatani M.2001.Conceptual and physical clarification of rate and state friction:Frictional sliding as a thermally activated rheology[J].Journal of Geophysical Research:Atmospheres,106(B7):13347-13380.
Rice J R,Lapusta N,Ranjith K.2001.Rate and state dependent friction and the stability of sliding between elastically deformable solids[J].Mech Phys Solids,49:1865-1898.
Ruina A.1983.Slip instability and state variable friction law[J].Journal of Geophysical Research,88(B12):10359-10370.
Tse S T,Rice J R.1986.Crustal earthquake instability in relation to the depth variation of frictional slip propertie[J].Journal of Geophysical Research:Atmospheres,91(B9):9452-9472.
Wong I G,Chapman D S.1990.Deep intraplate earthquakes in the western United States and their relationship t lithospheric temperatures[J].Bulletin of the Seismological Society of America,80(3):589-599.