汶川地震断层带中碳酸盐岩碳氧同位素分异——对断层愈合机制的启示
|
摘要
汶川地震断层带北川擂鼓镇赵家沟剖面的露头及显微结构均发现多期次脉体纵横交错,角砾岩被胶结。通过对断层岩相关的碳酸盐矿物同位素分析得知,断层岩角砾和脉体中大量的白云石来源应是断层带内富Mg离子的流体,且碳氧同位素显著分异,角砾的δ~(18)O值和δ~(13)C值与灰岩围岩更接近,脉体和基质显示重同位素亏损。通过"同震热分解"和"水-岩相互作用"2种可能模型的研究分析,同震热分解模型δ~(13)C值明显高于实际,而水-岩相互作用则可形成这种分异结果。故震后深部流体上涌所导致的表层大气水再循环可能是导致震后断层快速愈合的重要原因,同震破裂和间震期愈合则形成完整的断层系统。
The outcrop and microscopic structure analysis of Zhaojiagou section at Leigu Town in Beichuan area of Wenchuan earthquake fault zone revealed that multi-phase veins crisscross and the breccia has been cemented.The isotope analysis of carbonate minerals related to fault rocks shows that the source of a large amount of dolomite in the fault breccia and veins should be the Mgrich fluid in the fault zone,and the carbon and oxygen isotopes exhibit significant differentiation.The δ~(18)O and δ~(13)C values of breccia are more close to values of surrounding rocks of limestone, and the veins and matrix exhibit heavy isotope losses. It is found that the δ~(13)C values of the coseismic thermal decomposition model is obviously higher than the real values and the water-rock interaction model can form this differentiation result, as shown by comparison of these two possible models.Therefore, the surface water recirculation caused by the upwelling of deep fluids may be the significant cause of the fault rapid healing after earthquake. The coseismic rupture and inter-seismic healing form a complete fault system.
The outcrop and microscopic structure analysis of Zhaojiagou section at Leigu Town in Beichuan area of Wenchuan earthquake fault zone revealed that multi-phase veins crisscross and the breccia has been cemented.The isotope analysis of carbonate minerals related to fault rocks shows that the source of a large amount of dolomite in the fault breccia and veins should be the Mgrich fluid in the fault zone,and the carbon and oxygen isotopes exhibit significant differentiation.The δ~(18)O and δ~(13)C values of breccia are more close to values of surrounding rocks of limestone, and the veins and matrix exhibit heavy isotope losses. It is found that the δ~(13)C values of the coseismic thermal decomposition model is obviously higher than the real values and the water-rock interaction model can form this differentiation result, as shown by comparison of these two possible models.Therefore, the surface water recirculation caused by the upwelling of deep fluids may be the significant cause of the fault rapid healing after earthquake. The coseismic rupture and inter-seismic healing form a complete fault system.
引文
[1]Li Y G, Vidale J E, Day S M, et al. Postseismic fault healing on the rupture zone of the 1999 M 7.1 Hector Mine, California, earthquake[J].Bulletin seismological Society of America, 2003,93(2):854-869.
[2]Kitagawa Y, Fujirmori K, Koizumi N. Temporal change in permeability of the Nojima fault zone by repeated water injection experiments[J]. Tectonophysics, 2007,443:183-192.
[3]Xue L, Li H B, Brodsky E E, et al. Continuous permeability measurements record healing inside the Wenchuan Earthquake Fault Zone[J]. Science,2013,340(6140):1555-1559.
[4]Marone C. Laboratory-derived friction laws and their application to seismic faulting[J]. Annual Review of Earth and Planetary Sciences,1998,26(1):643-696.
[5]Wang P L, Wu J J, Yeh E C, et al. Isotopic constraints of vein carbonates on fluid sources and processes associated with the ongoing brittle deformation within the accretionary wedge of Taiwan[J].Terra Nova, 2010,22(4):251-256.
[6]Gratier J P, Richard J, Renard F, et al. Aseismic sliding of active faults by pressure solution creep:Evidence from the San Andreas Fault Observatory at Depth[J]. Geology,2011,39(12):1131-1134.
[7]Hickman S, Sibson R, Bruhn R. Introduction to special section:Mechanical involvement of fluids in faulting[J]. Journal of Geophysical Research Atmospheres, 1995,100(B7):12831-12840.
[8]Kanagawa K, Cox S F, Zhang S. Effects of dissolution precipitation processes on the strength and mechanical behavior of quartz gouge at high-temperature hydrothermal conditions[J]. Journal of Geophysical Research Atmospheres, 2000, 105(B5):11115-11126.
[9]Yasuhara H, Marone C, Elsworth D. Fault zone restrengthening and frictional healing:The role of pressure solution[J]. Journal of Geophysical Research Atmospheres, 2005,110(6):10-1029.
[10]Chen J Y, Yang X S, Duan Q B, et al. Importance of thermochemical pressurization in the dynamic weakening of the Longmenshan Fault during the 2008 Wenchuan earthquake:Inferences from experiments and modeling[J]. Journal of Geophysical Research Atmospheres, 2013, 118(8):4145-4169.
[11]Yang T, Chen J, Wang H, et al. Rock magnetic properties of fault rocks from the rupture of the 2008 Wenchuan earthquake, China and their implications:Preliminary results from the Zhaojiagou outcrop, Beichuan County(Sichuan)[J]. Tectonophysics, 2012,s530-531(2):331-341.
[12]陈建业,杨晓松,党嘉祥,等.汶川地震断层带结构及渗透率[J].地球物理学报, 2011,54(7):1805-1816.
[13]Zhang L, He C. Frictional properties of natural gouges from Longmenshan fault zone ruptured during the Wenchuan Mw7.9earthquake[J].Tectonophysics, 2013,594(3):149-164.
[14]Shieh Y N, Taylor H P. Carbon and hydrogen isotope studies at contact metamorphism in the Santa Rosa Range, Nevada and other areas[J]. Contributions to Mineralogy and Petrology, 1969, 20(4):306-356.
[15]Hirose T, Shimamoto T. Growth of molten zone as a mechanism of slip weakening of simulated faults in gabbro during frictional melting[J]. Journal of Geophysical Research Solid Earth, 2005, 110(B5):147-155.
[16]Hirono T, Fujimoto K, Yokoyama T, et al. Clay mineral reactions caused by frictional heating during an earthquake:An example from the Taiwan Chelungpu fault[J].Geophysical Research Letters,2008,35:L16303.
[17]Han R, Shimamoto T, Hirose T, et al. Ultralow friction of carbonate faults caused by thermal decomposition[J]. Science, 2007,316(5826):878-881.
[18]Hirono T, Ikehara M, Otsuki K, et al. Evidence of frictional melting from disk-shaped black material, discovered within the Taiwan Chelungpu fault system[J]. Geophysical Research Letters,2006,33(19):677-688.
[19]Di Toro G, Han R, Hirose T, et al. Fault lubrication during earthquakes[J]. Nature, 2011,471(7339):494-498.
[20]De Paola N, Chiodini G, Hirose T, et al. The geochemical signature caused by earthquake propagation in carbonate-hosted faults[J]. Earth and Planet Science Letters, 2011, 310(3):225-232.
[21]Sheppard S M, Schwarcz H P. Fractionation of carbon and oxygen isotopes and magnesium between coexisting metamorphic calcite and dolomite[J]. Contributions to Mineralogy and Petrology,1970,26(3):161-198.
[22]Hausegger S, Kurz W, Rabitsch R, et al. Analysis of the internal structure of a carbonate damage zone:Implications for the mechanisms of fault breccia formation and fluid flow[J].Journal of Structural Geology, 2010, 32(9):1349-1362.
[23]Molli G, Cortecci G, Vaselli L, et al. Fault zone structure and fluidrock interaction of a high angle normal fault in Carrara marble(NW Tuscany, Italy)[J]. Journal of Structural Geology,2010, 32(9):1334-1348.
[24]Kirschner D L, Kennedy L A. Limited syntectonic fluid flow in carbonate-hosted thrust faults of the Front Ranges, Canadian Rockies, inferred from stable isotope data and structures[J]. Journal of Geophysical Research Atmospheres,2001,106(B5):8827-8840.
[25]Pili E, Poitrasson F, Gratier J P. Carbon-oxygen isotope and trace element constraints on how fluids percolate faulted limestones from the San Andreas Fault system:partitioning of fluid sources and pathways[J]. Chemical Geology, 2002,190(1/4):231-250.
[26]Pili E, Kennedy B M, Conrad M. E, et al. Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System[J].Chemical Geology, 2011, 281(3/4):242-252.
[27]Hellings L, Dehairs F, Tackx M, et al. Origin and fate of organic carbon in the freshwater part of the Scheldt Estuary as traced by stable carbon isotope composition[J]. Biogeochemistry, 1999,47(2):167-186.
[28]Ballentine C, O’Nions R K. The use of natural He, Ne and Ar isotopes to study hydrocarbon-related fluid provenance, migration and mass balance in sedimentary basins[J]. Geological Society Special Publication, 1994,78(1):347-361.
[29]Zheng Y F, Hoefs J. Carbon and oxygen isotopic covariations in hydrothermal calcites[J]. Mineralium Deposita,1993,28(2):79-89.
[30]Ohomoto H, Rye R O. Isotopes of sulfur and Carbon, in Geochemistry of Hydrothermal Ore Deposits, edited by H. L.Barnes[M]. New York:Wiley, 1979:509-567.
[31]O'Neil J R, Clayton R N, Mayeda T K. Oxygen Isotope Fractionation in Divalent Metal Carbonates[J]. Journal of Chemical Physics, 1969,51(12):5547-5558.
[32]Chen J Y, Yang X S, Ma, S L, et al. Mass removal and clay mineral dehy-dration/rehydration in carbonate-rich surface exposures of the 2008 Wenchuan Earthquake fault:geochemical evidence and implications for fault zone evolution and coseismic slip[J]. Journal of Geophysical Research:Solid Earth, 2013,118(2):474-496.
[2]Kitagawa Y, Fujirmori K, Koizumi N. Temporal change in permeability of the Nojima fault zone by repeated water injection experiments[J]. Tectonophysics, 2007,443:183-192.
[3]Xue L, Li H B, Brodsky E E, et al. Continuous permeability measurements record healing inside the Wenchuan Earthquake Fault Zone[J]. Science,2013,340(6140):1555-1559.
[4]Marone C. Laboratory-derived friction laws and their application to seismic faulting[J]. Annual Review of Earth and Planetary Sciences,1998,26(1):643-696.
[5]Wang P L, Wu J J, Yeh E C, et al. Isotopic constraints of vein carbonates on fluid sources and processes associated with the ongoing brittle deformation within the accretionary wedge of Taiwan[J].Terra Nova, 2010,22(4):251-256.
[6]Gratier J P, Richard J, Renard F, et al. Aseismic sliding of active faults by pressure solution creep:Evidence from the San Andreas Fault Observatory at Depth[J]. Geology,2011,39(12):1131-1134.
[7]Hickman S, Sibson R, Bruhn R. Introduction to special section:Mechanical involvement of fluids in faulting[J]. Journal of Geophysical Research Atmospheres, 1995,100(B7):12831-12840.
[8]Kanagawa K, Cox S F, Zhang S. Effects of dissolution precipitation processes on the strength and mechanical behavior of quartz gouge at high-temperature hydrothermal conditions[J]. Journal of Geophysical Research Atmospheres, 2000, 105(B5):11115-11126.
[9]Yasuhara H, Marone C, Elsworth D. Fault zone restrengthening and frictional healing:The role of pressure solution[J]. Journal of Geophysical Research Atmospheres, 2005,110(6):10-1029.
[10]Chen J Y, Yang X S, Duan Q B, et al. Importance of thermochemical pressurization in the dynamic weakening of the Longmenshan Fault during the 2008 Wenchuan earthquake:Inferences from experiments and modeling[J]. Journal of Geophysical Research Atmospheres, 2013, 118(8):4145-4169.
[11]Yang T, Chen J, Wang H, et al. Rock magnetic properties of fault rocks from the rupture of the 2008 Wenchuan earthquake, China and their implications:Preliminary results from the Zhaojiagou outcrop, Beichuan County(Sichuan)[J]. Tectonophysics, 2012,s530-531(2):331-341.
[12]陈建业,杨晓松,党嘉祥,等.汶川地震断层带结构及渗透率[J].地球物理学报, 2011,54(7):1805-1816.
[13]Zhang L, He C. Frictional properties of natural gouges from Longmenshan fault zone ruptured during the Wenchuan Mw7.9earthquake[J].Tectonophysics, 2013,594(3):149-164.
[14]Shieh Y N, Taylor H P. Carbon and hydrogen isotope studies at contact metamorphism in the Santa Rosa Range, Nevada and other areas[J]. Contributions to Mineralogy and Petrology, 1969, 20(4):306-356.
[15]Hirose T, Shimamoto T. Growth of molten zone as a mechanism of slip weakening of simulated faults in gabbro during frictional melting[J]. Journal of Geophysical Research Solid Earth, 2005, 110(B5):147-155.
[16]Hirono T, Fujimoto K, Yokoyama T, et al. Clay mineral reactions caused by frictional heating during an earthquake:An example from the Taiwan Chelungpu fault[J].Geophysical Research Letters,2008,35:L16303.
[17]Han R, Shimamoto T, Hirose T, et al. Ultralow friction of carbonate faults caused by thermal decomposition[J]. Science, 2007,316(5826):878-881.
[18]Hirono T, Ikehara M, Otsuki K, et al. Evidence of frictional melting from disk-shaped black material, discovered within the Taiwan Chelungpu fault system[J]. Geophysical Research Letters,2006,33(19):677-688.
[19]Di Toro G, Han R, Hirose T, et al. Fault lubrication during earthquakes[J]. Nature, 2011,471(7339):494-498.
[20]De Paola N, Chiodini G, Hirose T, et al. The geochemical signature caused by earthquake propagation in carbonate-hosted faults[J]. Earth and Planet Science Letters, 2011, 310(3):225-232.
[21]Sheppard S M, Schwarcz H P. Fractionation of carbon and oxygen isotopes and magnesium between coexisting metamorphic calcite and dolomite[J]. Contributions to Mineralogy and Petrology,1970,26(3):161-198.
[22]Hausegger S, Kurz W, Rabitsch R, et al. Analysis of the internal structure of a carbonate damage zone:Implications for the mechanisms of fault breccia formation and fluid flow[J].Journal of Structural Geology, 2010, 32(9):1349-1362.
[23]Molli G, Cortecci G, Vaselli L, et al. Fault zone structure and fluidrock interaction of a high angle normal fault in Carrara marble(NW Tuscany, Italy)[J]. Journal of Structural Geology,2010, 32(9):1334-1348.
[24]Kirschner D L, Kennedy L A. Limited syntectonic fluid flow in carbonate-hosted thrust faults of the Front Ranges, Canadian Rockies, inferred from stable isotope data and structures[J]. Journal of Geophysical Research Atmospheres,2001,106(B5):8827-8840.
[25]Pili E, Poitrasson F, Gratier J P. Carbon-oxygen isotope and trace element constraints on how fluids percolate faulted limestones from the San Andreas Fault system:partitioning of fluid sources and pathways[J]. Chemical Geology, 2002,190(1/4):231-250.
[26]Pili E, Kennedy B M, Conrad M. E, et al. Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System[J].Chemical Geology, 2011, 281(3/4):242-252.
[27]Hellings L, Dehairs F, Tackx M, et al. Origin and fate of organic carbon in the freshwater part of the Scheldt Estuary as traced by stable carbon isotope composition[J]. Biogeochemistry, 1999,47(2):167-186.
[28]Ballentine C, O’Nions R K. The use of natural He, Ne and Ar isotopes to study hydrocarbon-related fluid provenance, migration and mass balance in sedimentary basins[J]. Geological Society Special Publication, 1994,78(1):347-361.
[29]Zheng Y F, Hoefs J. Carbon and oxygen isotopic covariations in hydrothermal calcites[J]. Mineralium Deposita,1993,28(2):79-89.
[30]Ohomoto H, Rye R O. Isotopes of sulfur and Carbon, in Geochemistry of Hydrothermal Ore Deposits, edited by H. L.Barnes[M]. New York:Wiley, 1979:509-567.
[31]O'Neil J R, Clayton R N, Mayeda T K. Oxygen Isotope Fractionation in Divalent Metal Carbonates[J]. Journal of Chemical Physics, 1969,51(12):5547-5558.
[32]Chen J Y, Yang X S, Ma, S L, et al. Mass removal and clay mineral dehy-dration/rehydration in carbonate-rich surface exposures of the 2008 Wenchuan Earthquake fault:geochemical evidence and implications for fault zone evolution and coseismic slip[J]. Journal of Geophysical Research:Solid Earth, 2013,118(2):474-496.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |