苏鲁-大别超高压变质岩的弹性力学性质与密度的关系
摘要
我们采集了31块来自中国大陆科学钻探(CCSD)主孔和预先导孔岩芯以及29块苏鲁-大别地区地表露头的典型超高压变质岩,在10～850 MPa的静水压力和室温下测量了60块标本的P波与S波速度,分别建立了纵横波速和围压之间的定量关系,并在此基础上计算了不同压力下各岩石标本的弹性参数即杨氏模量(E)、剪切模量(G)、体模量(K)和泊松比(v),着重探讨了超高压变质岩的弹性力学性质与密度之间的关系。这些最新成果将为超高压变质岩地区以及新老俯冲带地震波资料的解释提供关键的理论和实验基础。
Elastic properties of rocks provide important constraints for the chemical composition,structure and physical state of the Earth's interior.We have experimentally determined both P-and S-wave velocities of 60 typical UHP metamorphic rock samples among which 31 were collected from the CCSD(Chinese Continental Scientific Drilling)main and pre-pilot holes and 29 from the surface outcrops in the Sulu-Dabie orogenic belt(China)at ambient temperature and hydrostatic confining pressures up to 850 MPa.The velocity-pressure curves were well described by a four-parameter expression.The elastic constants(e.g.,Young's modulus E,shear modulus G,bulk modulus K and Poisson's ratio v)of each sample were computed from P-and S-wave velocities measured during depressurization.At each given pressure,the correlation between an elastic modulus(M)and density(p)can be well fitted by an empirical equation:M=ap~3+bp~2+cp,where a,b and c are adjustable coefficients.Except of monomineralic rocks such as quartzite,serpentinite,anorthosite,limestone and marble and serpentinized peridotite,all the other types of rocks have their Poisson's ratios falling along an upward convex trend line determined from the correlations between elastic moduli and density.Poisson's ratios increases as lithology changes from granite,schist,felsic gneiss,through diorite-syenite,intermediate gneiss and metasediment,to gabbro-diabase,amphibolite,and mafic gneiss,and then decrease as the rocks become ultramafic in composition(i.e.,pyroxenite and peridotite).Eclogite has a higher density but a lower Poisson' s ratio than peridotite.The increase in v with rock type,ranging from felsic gneisses to metagabbro,is correlated with systematic variations of quartz and feldspar contents in the rocks.An increase in quartz content induces a decrease in v while an increase in feldspar content causes an increase in v.An increase in the anorthite content of plagioclase also increases the Poisson's ratio of bulk rock.Serpentinization can significantly raise the Poisson' s ratio of peridotites because serpentinite possesses an extremely high value of v.However,the contribution of each constituent mineral to the bulk Poisson's ratio of a polymineralic rock can be analyzed for the moment only in a qualitative manner because mixture rules for Poisson's ratio are unavailable.The results provide a complete set of basic information for the interpretation of field seismic data from the UHP metamorphic terranes and modern and ancient subduction zones.
Elastic properties of rocks provide important constraints for the chemical composition,structure and physical state of the Earth's interior.We have experimentally determined both P-and S-wave velocities of 60 typical UHP metamorphic rock samples among which 31 were collected from the CCSD(Chinese Continental Scientific Drilling)main and pre-pilot holes and 29 from the surface outcrops in the Sulu-Dabie orogenic belt(China)at ambient temperature and hydrostatic confining pressures up to 850 MPa.The velocity-pressure curves were well described by a four-parameter expression.The elastic constants(e.g.,Young's modulus E,shear modulus G,bulk modulus K and Poisson's ratio v)of each sample were computed from P-and S-wave velocities measured during depressurization.At each given pressure,the correlation between an elastic modulus(M)and density(p)can be well fitted by an empirical equation:M=ap~3+bp~2+cp,where a,b and c are adjustable coefficients.Except of monomineralic rocks such as quartzite,serpentinite,anorthosite,limestone and marble and serpentinized peridotite,all the other types of rocks have their Poisson's ratios falling along an upward convex trend line determined from the correlations between elastic moduli and density.Poisson's ratios increases as lithology changes from granite,schist,felsic gneiss,through diorite-syenite,intermediate gneiss and metasediment,to gabbro-diabase,amphibolite,and mafic gneiss,and then decrease as the rocks become ultramafic in composition(i.e.,pyroxenite and peridotite).Eclogite has a higher density but a lower Poisson' s ratio than peridotite.The increase in v with rock type,ranging from felsic gneisses to metagabbro,is correlated with systematic variations of quartz and feldspar contents in the rocks.An increase in quartz content induces a decrease in v while an increase in feldspar content causes an increase in v.An increase in the anorthite content of plagioclase also increases the Poisson's ratio of bulk rock.Serpentinization can significantly raise the Poisson' s ratio of peridotites because serpentinite possesses an extremely high value of v.However,the contribution of each constituent mineral to the bulk Poisson's ratio of a polymineralic rock can be analyzed for the moment only in a qualitative manner because mixture rules for Poisson's ratio are unavailable.The results provide a complete set of basic information for the interpretation of field seismic data from the UHP metamorphic terranes and modern and ancient subduction zones.
引文
Birch F.1960.The velocity of compressional waves in rocks to 10 kilobar:Part 1.Journal of Geophysical Research,65:1083-1102
Christensen NI.1996.Poisson's ratio and crustal seismology.Journal of Geophysical Research,101:3139-3156
Christensen NI,Ramananantoandro R.1971.Elastic moduli and anisotropy of dunite to 10 kilobars.Journal of Geophysical Research, 76:4003-4010
Dunn ML,Ledbetter H.1995.Poisson's ratio of porous and microcracked solids:Theory and application to oxide superconductors.Journal of Materials Research,10:2715-2722
Gercek H.2007.Poisson's ratio values for rocks.International Journal of Rock Mechanics and Mining Sciences,44:1-13
Gorecki T.1980.The relations between the shear modulus,the bulk modulus and Young's modulus for polycrystalline metallic elements. Materials Science and Engineering,43:225-230
Holbrook WS,Gajewski P,Krammer A,Prodehl C.1988.An interpretation of wide-angle compressional and shear wave data in southwest Germany:Poisson's ratio and petrological implications. Journal of Geophysical Research,93:12081-12106
Ji SC,Wang Q,Marcotte D,Salisbury M H,Xu Z Q.2007.P-wave velocities,anisotropy and hysteresis in ultrahigh-pressure metamorphic rocks as a function of confining pressure.Journal of Geophysical Research,12,doi:10.1029/2006JB004867
Ji SC,Gu Q,Xia B.2006.Porosity dependence of mechanical properties of solid materials.Journal of Materials Science,41:1757-1768
Ji SC,Wang Q,Xia B.2002.Handbook of Seismic Properties of Minerals,Rocks and Ores.Polytechnic International Press, Montreal,630 pp
Ji SC,Wang Q,Xia B,Marcotte D.2004.Mechanical properties of multiphase materials and rocks:A phenomenological approach using generalized means.Journal of Structural Geology,26:1377-I390
Ji SC,Salisbury MH,Hanmer S.1993.Petrofabric,P-wave anisotropy and seismic reflectivity of high-grade tectonites.Tectonophysics, 222:195-226
Ji SC,Salisbury MH.1993.Shear-wave velocities,anisotropy and splitting in the high grade mylonites.Tectonophysics,221:453- 473
Kern H,Gao S,Jin Z,Popp T,Jin S.1999.Petrophysical studies on rocks from the Dabie ultrahigh-pressure(UHP)metamorphic belt, central China:Implications for the composition and delamination of the lower crust.Tectonophysics,301:191-215
Kern H,Jin ZM,Gao S,Popp T,Xu ZQ.2002.Physical properties of ultrahigh-pressure metamorphic rocks from the Sulu terrain,eastern central China:Implications for the seismic structure at the Donghai (CCSD)drilling site.Tectonophysics,354:315-330
Koster W,Franz H.1961.Poisson's ratio for metals and alloys. Metallurgical Reviews,6:1-55
Lakes RS.1987.Foam structures with a negative Poisson's ratio. Science,235:1038-1040
Ledbetter HM.1973.Poisson's ratio for polycrystals.Journal of Physics and Chemistry of Solids,34:72l-723
Ledbetter HM.1977.Ratio of the shear and Young's Moduli for polycrystalline metallic elements.Materials Science and Engineering, 27:133-I35
Mavko G,Mukerji T,Dyorkin J.1998.The Rock Physics Handbook: Tools fur Seismic Analysis of Porous Media.New York:Cambridge University Press,339 pp
Mishra OP,Zhao DP.2003.Crack density,saturation rate and porosity at the 2001 Bhuj,India,earthquake hypocenter:A fluid-driven earthquake?Earth and Planetary.Science Letters,212:393-405
Phani KK,Sanyal D.2005.Critical reevaluation of the prediction of effective Poisson's ratio for porous materials.Journal of Materials Science,40:5685-5690
Roberts A,Garboczi EJ.2000.Elastic properties of model porous ceramics.Journal of the American Ceramic Society,12:3041-3048
Wang Q,Ji SC,Salisbury MH,Pan MB,Xia B,Xu ZQ.2005a. Pressure dependence and anisotropy of P-wave velocities in ultrahigh- pressure metamorphic rocks from the Dabie-Sulu orogenic belt (China):Iimplications for seismic properties of subducted slabs and origin of mantle reflections.Tectonophysics,398:67-99
Wang Q,Ji SC,Salisbury MH,Xia B,Pan MB,Xu ZQ.2005b.Shear wave properties and Poisson's ratios of ultrahigh-pressure metamorphic rocks from the Dabie-Sulu orogenic belt:Implications for the crustal composition.Journal of Geophysical Research,110:B08208,doi: 10.1029/2004JB003435
Wang ZC,Ji SC.2001.Elasticity of six polycrystalline silicate garnets at pressure up to 3.0 GPa.American Mineralogist,86:1209-1218
Wilkens R,Simmons G,Caruso L.1984.The ratio Vp/Vs as a discriminant ofcomposition for siliceous limestones.Geophysics,49: 1850-1860
Yeheskel O,Tevet O.2000.A new assessment method for the bulk modulus and the Poisson's ratio of porous ceramics.Journal of Testing and Evaluation,28:189-198
Zandt G and Ammon CJ.1995.Continental crust composition constrained by measurements of crustal Poisson's ratio.Nature,374:152-154
Christensen NI.1996.Poisson's ratio and crustal seismology.Journal of Geophysical Research,101:3139-3156
Christensen NI,Ramananantoandro R.1971.Elastic moduli and anisotropy of dunite to 10 kilobars.Journal of Geophysical Research, 76:4003-4010
Dunn ML,Ledbetter H.1995.Poisson's ratio of porous and microcracked solids:Theory and application to oxide superconductors.Journal of Materials Research,10:2715-2722
Gercek H.2007.Poisson's ratio values for rocks.International Journal of Rock Mechanics and Mining Sciences,44:1-13
Gorecki T.1980.The relations between the shear modulus,the bulk modulus and Young's modulus for polycrystalline metallic elements. Materials Science and Engineering,43:225-230
Holbrook WS,Gajewski P,Krammer A,Prodehl C.1988.An interpretation of wide-angle compressional and shear wave data in southwest Germany:Poisson's ratio and petrological implications. Journal of Geophysical Research,93:12081-12106
Ji SC,Wang Q,Marcotte D,Salisbury M H,Xu Z Q.2007.P-wave velocities,anisotropy and hysteresis in ultrahigh-pressure metamorphic rocks as a function of confining pressure.Journal of Geophysical Research,12,doi:10.1029/2006JB004867
Ji SC,Gu Q,Xia B.2006.Porosity dependence of mechanical properties of solid materials.Journal of Materials Science,41:1757-1768
Ji SC,Wang Q,Xia B.2002.Handbook of Seismic Properties of Minerals,Rocks and Ores.Polytechnic International Press, Montreal,630 pp
Ji SC,Wang Q,Xia B,Marcotte D.2004.Mechanical properties of multiphase materials and rocks:A phenomenological approach using generalized means.Journal of Structural Geology,26:1377-I390
Ji SC,Salisbury MH,Hanmer S.1993.Petrofabric,P-wave anisotropy and seismic reflectivity of high-grade tectonites.Tectonophysics, 222:195-226
Ji SC,Salisbury MH.1993.Shear-wave velocities,anisotropy and splitting in the high grade mylonites.Tectonophysics,221:453- 473
Kern H,Gao S,Jin Z,Popp T,Jin S.1999.Petrophysical studies on rocks from the Dabie ultrahigh-pressure(UHP)metamorphic belt, central China:Implications for the composition and delamination of the lower crust.Tectonophysics,301:191-215
Kern H,Jin ZM,Gao S,Popp T,Xu ZQ.2002.Physical properties of ultrahigh-pressure metamorphic rocks from the Sulu terrain,eastern central China:Implications for the seismic structure at the Donghai (CCSD)drilling site.Tectonophysics,354:315-330
Koster W,Franz H.1961.Poisson's ratio for metals and alloys. Metallurgical Reviews,6:1-55
Lakes RS.1987.Foam structures with a negative Poisson's ratio. Science,235:1038-1040
Ledbetter HM.1973.Poisson's ratio for polycrystals.Journal of Physics and Chemistry of Solids,34:72l-723
Ledbetter HM.1977.Ratio of the shear and Young's Moduli for polycrystalline metallic elements.Materials Science and Engineering, 27:133-I35
Mavko G,Mukerji T,Dyorkin J.1998.The Rock Physics Handbook: Tools fur Seismic Analysis of Porous Media.New York:Cambridge University Press,339 pp
Mishra OP,Zhao DP.2003.Crack density,saturation rate and porosity at the 2001 Bhuj,India,earthquake hypocenter:A fluid-driven earthquake?Earth and Planetary.Science Letters,212:393-405
Phani KK,Sanyal D.2005.Critical reevaluation of the prediction of effective Poisson's ratio for porous materials.Journal of Materials Science,40:5685-5690
Roberts A,Garboczi EJ.2000.Elastic properties of model porous ceramics.Journal of the American Ceramic Society,12:3041-3048
Wang Q,Ji SC,Salisbury MH,Pan MB,Xia B,Xu ZQ.2005a. Pressure dependence and anisotropy of P-wave velocities in ultrahigh- pressure metamorphic rocks from the Dabie-Sulu orogenic belt (China):Iimplications for seismic properties of subducted slabs and origin of mantle reflections.Tectonophysics,398:67-99
Wang Q,Ji SC,Salisbury MH,Xia B,Pan MB,Xu ZQ.2005b.Shear wave properties and Poisson's ratios of ultrahigh-pressure metamorphic rocks from the Dabie-Sulu orogenic belt:Implications for the crustal composition.Journal of Geophysical Research,110:B08208,doi: 10.1029/2004JB003435
Wang ZC,Ji SC.2001.Elasticity of six polycrystalline silicate garnets at pressure up to 3.0 GPa.American Mineralogist,86:1209-1218
Wilkens R,Simmons G,Caruso L.1984.The ratio Vp/Vs as a discriminant ofcomposition for siliceous limestones.Geophysics,49: 1850-1860
Yeheskel O,Tevet O.2000.A new assessment method for the bulk modulus and the Poisson's ratio of porous ceramics.Journal of Testing and Evaluation,28:189-198
Zandt G and Ammon CJ.1995.Continental crust composition constrained by measurements of crustal Poisson's ratio.Nature,374:152-154
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