岩石地震波性质的实验与理论研究
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摘要
岩石的地震波性质是解释地震观测资料的基础。本文首先以中国大陆超深钻主孔的榴辉岩为例,将榴辉岩在高温高压(最大为500MPa和700℃)下观测矿物组成、晶格优选定向(LPO)、温度和压力对其地震波性质的影响。然后对岩石地震波性质数据库进行统计分析,指出长英质岩石的波速与石英或长石的含量没有相关性;从酸性岩、基性岩到超基性岩,随着SiO2含量的降低和铁镁矿物含量的增高,岩石波速逐渐增高,云母和角闪石的LPO是陆壳地震波各项异性的主要来源;波速与孔隙率的负相关受流体与压力的影响。
Seismic properties of rocks are fundamental for interpreting seismic observations. As a case study, an eclogite from the main hole of the Chinese Continental Scientific Drilling Project was collected to present an integrated study on seismic properties and microstructure of rocks. P-wave velocities of the eclogite were measured at pressures up to 500 MPa and temperatures up to 700 °C. The experimental results are compared with the calculated seismic velocities and anisotropy to investigate the effects of modal composition, lattice-preferred orientations (LPO) of minerals, pressure and temperature on seismic properties of eclogites. The statistical analysis on the Database of Rock Seismic Properties indicates that for felsic rocks there is no correlation between velocities and contents of quartz or feldspar. In general, seismic velocities of rocks increase with the decreasing SiO2 content and increasing volume fraction of mafic minerals. The seismic anisotropy of continental crust is mainly controlled by the LPO of mica and hornblende. Pore fluids and pressure will affect the negative correlation between porosity and seismic velocities of rocks.
Seismic properties of rocks are fundamental for interpreting seismic observations. As a case study, an eclogite from the main hole of the Chinese Continental Scientific Drilling Project was collected to present an integrated study on seismic properties and microstructure of rocks. P-wave velocities of the eclogite were measured at pressures up to 500 MPa and temperatures up to 700 °C. The experimental results are compared with the calculated seismic velocities and anisotropy to investigate the effects of modal composition, lattice-preferred orientations (LPO) of minerals, pressure and temperature on seismic properties of eclogites. The statistical analysis on the Database of Rock Seismic Properties indicates that for felsic rocks there is no correlation between velocities and contents of quartz or feldspar. In general, seismic velocities of rocks increase with the decreasing SiO2 content and increasing volume fraction of mafic minerals. The seismic anisotropy of continental crust is mainly controlled by the LPO of mica and hornblende. Pore fluids and pressure will affect the negative correlation between porosity and seismic velocities of rocks.
引文
[1]Christensen NI,Mooney WD.Seismic velocity structure and composition of the continental crust:A global view[J].J.Geophy.Res.,1995,100:9761-9788.
[2]Rudnick R L,Fountain D M.Nature and composition of the continental crust:Alower crustal perspective[J].Rev.Geo-phy.,1995,33:267-309.
[3]Gao S,Kern H,Liu Y,Jin S Y,Popp T,Jin Z M,Feng J,Sun M,Zhao Z.Measured and calculated seismic velocities and densities for granulites fromxenolith occurrences and adjacent exposed lower crustal sections:a comparative study fromthe North China craton[J].J.Geophy.Res.,2000,105:18965-18976.
[4]Park J,Levin V.Seismic anisotropy:tracing plate dynamicsin the mantle[J].Science,2002,296:485-489.
[5]Hearmon R F S.The elastic constants of crystals and other anisotropic materials[A].Hell wege K H,Hell wege A M.Landolt-Bornstein Tables,III/18[C].Berlin:Springer-Ver-lag,1984:1-154.
[6]Bass J D.Elasticity of minerals,glasses and melts[A].Ahr-ens TJ.Mineral Physics and Crystallography:Ahandbook of physical constants[C].Washington:American Geophysical Union,1995:45-63.
[7]Chai M,Brown J M,Slutsky LJ.The elastic constants of py-rope-grossuar-al mandine garnet to20GPa[J].Geophy.Res.Lett.,1997,24:523-526.
[8]Bhagat S,Bass J D,Smyth,J.Single-crystal elastic propertiesof omphacite-C2/c by Brillouin spectroscopy[J].J.Geophy.Res.,1992,97:6843-6848.
[9]Birch F.The velocity of compressional waves in rocks to10kilobar,Part1[J].J.Geophy.Res.,1960,65:1083-1102.
[10]Kern H.Elastic-wave velocity in crustal and mantle rocks at high pressure and temperature:The role of the high-low quartz transition and of dehydration reactions[J].Physics of the Earth and Planetary Interiors,1982,29:12-23.
[11]Christensen N I.Seismic velocities[A].Carmichael R.S.Practical Handbook of Physical Properties of Rocks and Min-erals[C].Boca Raton,Florida,America:CRC Press Inc.1989:429-546.
[12]Ji S C,Wang Q,Xia B.Handbook of seismic properties of minerals,rocks and ores[M].Montreal:Polytechnic Inter-national Press,2002:630.
[13]Crosson R S,Lin J W.Voigt and Reuss prediction of aniso-tropic elasticity of dunite[J].J.Geophy.Res.,1971,76:570-578.
[14]Mainprice D.A Fortran programto calculate seismic anisot-ropy from the lattice preferred orientation of minerals[J].Computers and Geosciences,1990,16:385-393.
[15]Mainprice D,Humbert M.Methods of calculating petrophys-ical properties fromlattice preferred orientation data[J].Sur-veys in Geophysics,1994,15:575-592.
[16]Xu Z Q,Wang Q,Ji S C,Chen J,Zeng L S,Yang J S,Chen F Y,Liang F H,Wenk H R.Petrofabrics and seismic prop-erties of garnet peridotite fromthe UHP Sulu terrane(Chi-na):I mplications for olivine deformation mechanismin a cold and dry subducting continental slab[J].Tectonophysics,2006,421:111-127.
[17]许志琴,王勤,陈方远,梁凤华,唐哲民.榴辉岩组构运动学与大陆深俯冲——中国大陆科学钻探主孔榴辉岩的EBSD研究[J].岩石学报,2006,22:1799-1809.Xu Zhiqin,Wang Qin,Chen Fangyuan,Liang Fenghua,Tang Zheming.Fabric kinematics of eclogite and deep conti-nental subduction:EBSDstudy of eclogite fromthe main hole of the Chinese Continental Scientific Drilling Project[J].Acta Petrologica Sinica,2006,22:1799-1809.(in Chinese with English abstract)
[18]Manghnani M H,Ramananantoandro R,Clark S P.Com-pressional and shear wave velocities in granulite facies rocks and eclogites to10kilobars[J].J.Geophy.Res.,1974,79:5427-5445.
[19]Kern H,Gao S,Jin Z,Popp T,Jin S.Petrophysical studies on rocks fromthe Dabie ultrahigh-pressure(UHP)metamor-phic belt,central China:I mplications for the composition and delamination of the lower crust[J].Tectonophysics,1999,301:191-215.
[20]Kern H,Jin Z,Gao S,Popp T,Xu Z Q.Physical properties of ultrahigh-pressure metamorphic rocks fromthe Sulu ter-rain,eastern central China:I mplications for the seismic structure at the Donghai(CCSD)drilling site[J].Tectono-physics,2002,354:315-330.
[21]Wang Q,Ji S C,Salisbury M,Pan M,Xia B,Xu Z Q.Pres-sure dependence and anisotropy of P-wave velocities in ultra-high-pressure metamorphic rocks from the Dabie-Sulu oro-genic belt(China):I mplications for seismic properties of sub-ducted slabs and origin of mantle reflections[J].Tectono-physics,2005,398:67-99.
[22]Wang Q,Ji S C,Salisbury M,Xia B,Pan M,Xu Z Q.Shear wave properties and Poisson's ratios of ultrahigh-pressure metamorphic rocks fromthe Dabie-Sulu orogenic belt,China:I mplications for the crustal composition[J].J.Geophy.Res.,2005,110,doi:10.1029/2004JB003435.
[23]Xu S T,Okay AI,Ji S,Seng r A MC,Su W,Liu Y,Jiang L.Diamond fromthe Dabie Shan metamorphic rocks and its i mplication for tectonic setting[J].Science,1992,256:5053,80-82.
[24]Liou J G,Zhang R Y,Ernst WG,Rumble D,Shigenori M.High-pressure minerals from deeply subducted metamorphic rocks[J].Rev.Miner.,1998,37:33-96.
[25]Liu F L,Xu Z Q,Katayama I,Yang J S,Maruyama Sh,Li-ou J G.Mineral inclusionsin Zircons of para-and orthogneiss frompre-pilot drillhole CCSD-PP1,Chinese Continental Sci-entific Drilling project[J].Lithos,2001,59:199-215.
[26]Burlini L,Arbaret L,Zeilinger G,Burg J P.High-tempera-ture and pressure seismic properties of a lower crustal pro-grade shear zone fromthe Kohistan Arc Pakistan[A].Bruhn D,Burlini L.High-Strain Zones:Structure and Physical Properties[C].Geol.Soc.Special Pub.,2005,245:187-202.
[27]Ferri F,Burlini L,Cesare B,Sassi R.Seismic properties of lower crustal xenoliths from El Hoyazo(SE Spain):Experi-mental evidence up to partial melting[J].Earth Planet.Sci.Lett.,2007,253:239-253.
[28]Nye J F.Physical Properties of Crystals:Their Representa-tion by Tensors and Matrices[M].London:Oxford Universi-ty Press,Amen House,1957:82-92.
[29]Hashin Z.Analysis of composite Materials-A survey[J].J.Appl.Mechan.,Transactions ASME,1983,50:481-505.
[30]Ji S C,Wang Q,Xia B.P-wave velocities of polymineralic rocks:comparison of theory and experi ment and test of elas-tic mixture rules[J].Tectonophysics,2003,366:165-185.
[31]Ji S C,Wang Q,Xia B,Marcotte D.Mechanical properties of multiphase materials and rocks:A phenomenological ap-proach using generalized means[J].J.Struc.Geol.,2004,26:1377-1390.
[32]Mauler A,Burlini L,Kunze K,Philippot P,Burg J P.P-wave anisotropyin eclogites and relationshipto the omphacite crystallographic fabric[J].Phy.Chem.Earth,2000,A25:119-126.
[33]Bascou J,Barruol G,Vauchez A,Mainprice D,Egydio-Silva M.EBSD-measured lattice-preferred orientations and seismic properties of eclogites[J].Tectonophysics,2001,342:61-80.
[34]Ji S C,Saruwatari K,Mainprice D,Wirth R,Xu Z Q,Xia B.Microstructures,petrofabrics and seismic properties of ul-trahigh-pressure eclogites fromthe Sulu region,China:I m-plications for rheology of subducted continental crust and ori-gin of mantle reflections[J].Tectonophysics,2003,370:49-76.
[35]Christensen NI.Poisson's ratio and crustal seismology[J].Journal of Geophysical Research,1996,101:3139-3156.
[36]Johnston J E,Christensen NI.Shear wave reflectivity,ani-sotropies,Poisson's ratios,and densities of a southern Appa-lachian Paleozoic sedi mentary sequence[J].Tectonophysics,1992,210:1-20.
[37]Godfrey N J,Christensen N I,Okaya D A.Anisotropy of schists:Contribution of crustal anisotropy to active source seismic experi ments and shear wave splitting observations[J].J.Geophy.Res.,2000,105:27991-28007.
[38]Siegesmund S,Takeshita T,Kern H.Anisotropy of Vp and Vs in an amphibolite of the deeper crust and its relationship to the mineralogical,microstructural andtextural characteris-tics of the rock[J].Tectonophysics,1989,157:25-38.
[39]Freund D.Ultrasonic compressional and shear velocities in dry clastic rocks as a function of porosity,clay content,and confining pressure[J].Geophy.J.Intern.,1992,108:125-135.
[40]Mechie J,Sobolev S V,Ratschbacher L,Babeyko A Y,Bock G,Jones A G,Nelson K D,Solon K D,Brown L D,Zhao W.Precise temperature esti mation in the Tibetan crust from seismic detection of theα-βquartz transition[J].Geology,2004,32:601-604.
[2]Rudnick R L,Fountain D M.Nature and composition of the continental crust:Alower crustal perspective[J].Rev.Geo-phy.,1995,33:267-309.
[3]Gao S,Kern H,Liu Y,Jin S Y,Popp T,Jin Z M,Feng J,Sun M,Zhao Z.Measured and calculated seismic velocities and densities for granulites fromxenolith occurrences and adjacent exposed lower crustal sections:a comparative study fromthe North China craton[J].J.Geophy.Res.,2000,105:18965-18976.
[4]Park J,Levin V.Seismic anisotropy:tracing plate dynamicsin the mantle[J].Science,2002,296:485-489.
[5]Hearmon R F S.The elastic constants of crystals and other anisotropic materials[A].Hell wege K H,Hell wege A M.Landolt-Bornstein Tables,III/18[C].Berlin:Springer-Ver-lag,1984:1-154.
[6]Bass J D.Elasticity of minerals,glasses and melts[A].Ahr-ens TJ.Mineral Physics and Crystallography:Ahandbook of physical constants[C].Washington:American Geophysical Union,1995:45-63.
[7]Chai M,Brown J M,Slutsky LJ.The elastic constants of py-rope-grossuar-al mandine garnet to20GPa[J].Geophy.Res.Lett.,1997,24:523-526.
[8]Bhagat S,Bass J D,Smyth,J.Single-crystal elastic propertiesof omphacite-C2/c by Brillouin spectroscopy[J].J.Geophy.Res.,1992,97:6843-6848.
[9]Birch F.The velocity of compressional waves in rocks to10kilobar,Part1[J].J.Geophy.Res.,1960,65:1083-1102.
[10]Kern H.Elastic-wave velocity in crustal and mantle rocks at high pressure and temperature:The role of the high-low quartz transition and of dehydration reactions[J].Physics of the Earth and Planetary Interiors,1982,29:12-23.
[11]Christensen N I.Seismic velocities[A].Carmichael R.S.Practical Handbook of Physical Properties of Rocks and Min-erals[C].Boca Raton,Florida,America:CRC Press Inc.1989:429-546.
[12]Ji S C,Wang Q,Xia B.Handbook of seismic properties of minerals,rocks and ores[M].Montreal:Polytechnic Inter-national Press,2002:630.
[13]Crosson R S,Lin J W.Voigt and Reuss prediction of aniso-tropic elasticity of dunite[J].J.Geophy.Res.,1971,76:570-578.
[14]Mainprice D.A Fortran programto calculate seismic anisot-ropy from the lattice preferred orientation of minerals[J].Computers and Geosciences,1990,16:385-393.
[15]Mainprice D,Humbert M.Methods of calculating petrophys-ical properties fromlattice preferred orientation data[J].Sur-veys in Geophysics,1994,15:575-592.
[16]Xu Z Q,Wang Q,Ji S C,Chen J,Zeng L S,Yang J S,Chen F Y,Liang F H,Wenk H R.Petrofabrics and seismic prop-erties of garnet peridotite fromthe UHP Sulu terrane(Chi-na):I mplications for olivine deformation mechanismin a cold and dry subducting continental slab[J].Tectonophysics,2006,421:111-127.
[17]许志琴,王勤,陈方远,梁凤华,唐哲民.榴辉岩组构运动学与大陆深俯冲——中国大陆科学钻探主孔榴辉岩的EBSD研究[J].岩石学报,2006,22:1799-1809.Xu Zhiqin,Wang Qin,Chen Fangyuan,Liang Fenghua,Tang Zheming.Fabric kinematics of eclogite and deep conti-nental subduction:EBSDstudy of eclogite fromthe main hole of the Chinese Continental Scientific Drilling Project[J].Acta Petrologica Sinica,2006,22:1799-1809.(in Chinese with English abstract)
[18]Manghnani M H,Ramananantoandro R,Clark S P.Com-pressional and shear wave velocities in granulite facies rocks and eclogites to10kilobars[J].J.Geophy.Res.,1974,79:5427-5445.
[19]Kern H,Gao S,Jin Z,Popp T,Jin S.Petrophysical studies on rocks fromthe Dabie ultrahigh-pressure(UHP)metamor-phic belt,central China:I mplications for the composition and delamination of the lower crust[J].Tectonophysics,1999,301:191-215.
[20]Kern H,Jin Z,Gao S,Popp T,Xu Z Q.Physical properties of ultrahigh-pressure metamorphic rocks fromthe Sulu ter-rain,eastern central China:I mplications for the seismic structure at the Donghai(CCSD)drilling site[J].Tectono-physics,2002,354:315-330.
[21]Wang Q,Ji S C,Salisbury M,Pan M,Xia B,Xu Z Q.Pres-sure dependence and anisotropy of P-wave velocities in ultra-high-pressure metamorphic rocks from the Dabie-Sulu oro-genic belt(China):I mplications for seismic properties of sub-ducted slabs and origin of mantle reflections[J].Tectono-physics,2005,398:67-99.
[22]Wang Q,Ji S C,Salisbury M,Xia B,Pan M,Xu Z Q.Shear wave properties and Poisson's ratios of ultrahigh-pressure metamorphic rocks fromthe Dabie-Sulu orogenic belt,China:I mplications for the crustal composition[J].J.Geophy.Res.,2005,110,doi:10.1029/2004JB003435.
[23]Xu S T,Okay AI,Ji S,Seng r A MC,Su W,Liu Y,Jiang L.Diamond fromthe Dabie Shan metamorphic rocks and its i mplication for tectonic setting[J].Science,1992,256:5053,80-82.
[24]Liou J G,Zhang R Y,Ernst WG,Rumble D,Shigenori M.High-pressure minerals from deeply subducted metamorphic rocks[J].Rev.Miner.,1998,37:33-96.
[25]Liu F L,Xu Z Q,Katayama I,Yang J S,Maruyama Sh,Li-ou J G.Mineral inclusionsin Zircons of para-and orthogneiss frompre-pilot drillhole CCSD-PP1,Chinese Continental Sci-entific Drilling project[J].Lithos,2001,59:199-215.
[26]Burlini L,Arbaret L,Zeilinger G,Burg J P.High-tempera-ture and pressure seismic properties of a lower crustal pro-grade shear zone fromthe Kohistan Arc Pakistan[A].Bruhn D,Burlini L.High-Strain Zones:Structure and Physical Properties[C].Geol.Soc.Special Pub.,2005,245:187-202.
[27]Ferri F,Burlini L,Cesare B,Sassi R.Seismic properties of lower crustal xenoliths from El Hoyazo(SE Spain):Experi-mental evidence up to partial melting[J].Earth Planet.Sci.Lett.,2007,253:239-253.
[28]Nye J F.Physical Properties of Crystals:Their Representa-tion by Tensors and Matrices[M].London:Oxford Universi-ty Press,Amen House,1957:82-92.
[29]Hashin Z.Analysis of composite Materials-A survey[J].J.Appl.Mechan.,Transactions ASME,1983,50:481-505.
[30]Ji S C,Wang Q,Xia B.P-wave velocities of polymineralic rocks:comparison of theory and experi ment and test of elas-tic mixture rules[J].Tectonophysics,2003,366:165-185.
[31]Ji S C,Wang Q,Xia B,Marcotte D.Mechanical properties of multiphase materials and rocks:A phenomenological ap-proach using generalized means[J].J.Struc.Geol.,2004,26:1377-1390.
[32]Mauler A,Burlini L,Kunze K,Philippot P,Burg J P.P-wave anisotropyin eclogites and relationshipto the omphacite crystallographic fabric[J].Phy.Chem.Earth,2000,A25:119-126.
[33]Bascou J,Barruol G,Vauchez A,Mainprice D,Egydio-Silva M.EBSD-measured lattice-preferred orientations and seismic properties of eclogites[J].Tectonophysics,2001,342:61-80.
[34]Ji S C,Saruwatari K,Mainprice D,Wirth R,Xu Z Q,Xia B.Microstructures,petrofabrics and seismic properties of ul-trahigh-pressure eclogites fromthe Sulu region,China:I m-plications for rheology of subducted continental crust and ori-gin of mantle reflections[J].Tectonophysics,2003,370:49-76.
[35]Christensen NI.Poisson's ratio and crustal seismology[J].Journal of Geophysical Research,1996,101:3139-3156.
[36]Johnston J E,Christensen NI.Shear wave reflectivity,ani-sotropies,Poisson's ratios,and densities of a southern Appa-lachian Paleozoic sedi mentary sequence[J].Tectonophysics,1992,210:1-20.
[37]Godfrey N J,Christensen N I,Okaya D A.Anisotropy of schists:Contribution of crustal anisotropy to active source seismic experi ments and shear wave splitting observations[J].J.Geophy.Res.,2000,105:27991-28007.
[38]Siegesmund S,Takeshita T,Kern H.Anisotropy of Vp and Vs in an amphibolite of the deeper crust and its relationship to the mineralogical,microstructural andtextural characteris-tics of the rock[J].Tectonophysics,1989,157:25-38.
[39]Freund D.Ultrasonic compressional and shear velocities in dry clastic rocks as a function of porosity,clay content,and confining pressure[J].Geophy.J.Intern.,1992,108:125-135.
[40]Mechie J,Sobolev S V,Ratschbacher L,Babeyko A Y,Bock G,Jones A G,Nelson K D,Solon K D,Brown L D,Zhao W.Precise temperature esti mation in the Tibetan crust from seismic detection of theα-βquartz transition[J].Geology,2004,32:601-604.
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