地壳主要岩石流变参数及华北地壳流变性质研究
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摘要
岩石流变参数和变形机制是根据断层摩擦和岩石幂次流动本构关系建立岩石圈强度剖面的基础。近 30年来 ,高温高压实验取得了很大进展 ,获得了大量地壳矿物和岩石流变资料。本文系统总结了这些流变实验资料 ,并应用流变数据结合地震震源深度分布 ,对华北地壳流变性质进行了研究。结果表明 ,以花岗岩和低级变质岩为代表的上地壳为脆性破裂 ,其强度受断层摩擦约束 ,以长英质片麻岩为主的中地壳和以中性麻粒岩为主的下地壳上层处于塑性流变状态 ,由干的基性麻粒岩组成的下地壳下层处于脆性向塑性流变的过渡状态。华北地壳的这种物质组成和流变为地壳不同层次的解耦和强震孕育提供了力学条件 ,也构成了不同尺度块体的底边界。
Rheological parameters and deformation mechanisms of rocks are the basis for estimating crustal strength by using frictional constitutive equations and power law creep equations. In the past 30 years, substantial progress has been made in high-temperature and high-pressure experimental studies, which provide a large numbers of data on rheological parameters of crustal minerals and rocks, as well as new insights into the deformation mechanisms. In this paper, we summarize systematically the existing experimental data, and study crustal rheology of North China by using these data combined with focal depth distributions in this region. The results show that the upper crust as represented by granite and low-grade metamorphic rocks is deformed in brittle faulting and frictional sliding regime, the strength of which is controlled by friction on faults; the middle crust comprising felsic-gneiss, as well as the upper layer of lower crust composed of intermediate granulite behave in plastic flow regime; the lower layer of lower crust consists of dry mafic granulite, which behaves in brittle-plastic flow transition regime. The composition and rheological stratification of the crust in North China may cause decoupling of different crustal layers and provide mechanical conditions for strong earthquake generation. In addition, they may also serve as the bottom boundaries for blocks of different scales.
Rheological parameters and deformation mechanisms of rocks are the basis for estimating crustal strength by using frictional constitutive equations and power law creep equations. In the past 30 years, substantial progress has been made in high-temperature and high-pressure experimental studies, which provide a large numbers of data on rheological parameters of crustal minerals and rocks, as well as new insights into the deformation mechanisms. In this paper, we summarize systematically the existing experimental data, and study crustal rheology of North China by using these data combined with focal depth distributions in this region. The results show that the upper crust as represented by granite and low-grade metamorphic rocks is deformed in brittle faulting and frictional sliding regime, the strength of which is controlled by friction on faults; the middle crust comprising felsic-gneiss, as well as the upper layer of lower crust composed of intermediate granulite behave in plastic flow regime; the lower layer of lower crust consists of dry mafic granulite, which behaves in brittle-plastic flow transition regime. The composition and rheological stratification of the crust in North China may cause decoupling of different crustal layers and provide mechanical conditions for strong earthquake generation. In addition, they may also serve as the bottom boundaries for blocks of different scales.
引文
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武城,徐杰,杨主恩主编.1992.上海奉贤至内蒙古阿拉善左旗地学断面〔Z〕.北京:地震出版社.
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汪洋.1999.中国大陆大地热流分析〔D〕:〔学位论文〕.北京:中国科学院地质研究所.
WANGYang.1999.AnAnalysisfortheContinentalHeatFlowinChina〔D〕.PhDthesis.Instituteofgeology,ChineseAcademyofSciences,Beijing(inChinese).
周永胜,何昌荣.2002.华北地区壳内低速层与地壳流变的关系及其对强震孕育的影响〔J〕.地震地质,24(1):124—132.
ZHOUYong sheng,HEChang rong.2002.TherelationshipbetweenlowvelocitylayersandrheologyofthecrustinnortheastChinaanditseffectonstrongearthquake〔J〕.SeismologyandGeology,24(1):124—132(inChi nese).
AveLallemantHG .1978.Experimentaldeformationofdiopsideandwebsterite〔J〕.Tectonophysics,48(1):1—27.
BaldermanMA .1974.Theeffectofstrainrateandtemperatureontheyieldpointofhydrolyticallyweakenedsyn theticquartz〔J〕.JourGeophysRes,79:1647—1652
.BlacicJD ,ChristleJM .1984.Plasticityandhydrolyticweakeningofquartzsinglecrystals〔J〕.JourGeophyRes,89(B6):4223—4239.
BokelmannGHR ,BerozaGC .2000.Depth dependentearthquakefocalmechanismorientationEvidenceforaweakzoneinthelowercrust〔J〕.JourGeophyRes,105(B9):21683—21695.
BolandJN ,TullisTE .1986.Deformationbehaviorofwetanddryclinopyroxeniteinthebrittletoductiletransitionregion〔A〕.In:HobbsBE ,HeardHC (eds).MineralandRockDeformation:LaboratoryStudies.GeophysMonogr36,AGU ,WashingtonDC .35—50.
BourneSJ ,EnglandPC ,ParsonsB .1998.Themotionofcrustalblocksdrivenbyflowofthelowerlithosphereandimplicationsfor
FANQi cheng,LIURuo xin.1996.HightemperaturegranulitexenolithinbasaltatHanuoba〔J〕.ChineseScienceBulletin,41(3):235—238(inChinese).
樊祺诚,刘若新,李惠民,等.1998.汉诺坝捕掳体麻粒岩锆石年代学与稀土元素地球化学〔J〕.科学通报,43(2):133—137.
FANQi cheng,LIURuo xin,LIHui min,etal.1998.ZirconchronologyandREE geochemistryofgranulitexenolithinbasaltatHanuoba〔J〕.ChineseScienceBulletin,43(2):133—137(inChinese).
高山,骆庭川,张本仁,等.1999.中国东部地壳的结构和组成〔J〕.中国科学(D辑),29(3):203—213.
GAOShan,LUOTing chuan,ZHANGBen ren,etal.1999.ThestructureandcompositionofcontinentalcrustineasternChina〔J〕.ScienceinChina(serD),29(3):203—213(inChinese).
国家地震局深部物探成果编写组.1986.中国地壳上地幔地球物理探测成果〔M〕.北京:地震出版社.
TheWritingGroupofProductionofDeepGeophysicalProspecting.1986.ProductionofGeophysicalProspectingforCrustandUpperMantleofChina〔M〕.SeismologicalPress,Beijing(inChinese).
何昌荣,周永胜,桑祖南.2002.四川攀枝花辉长岩半脆性-塑性流变的实验研究〔J〕.中国科学(D辑),32(9):717—726.
HEChang rong,ZHOUYong sheng,SANGZu nan.2002.Theexperimentalstudyofsemibrittle plasticrheologyofPanzhihuagabbroinSichuanProvince〔J〕.ScienceinChina,32(9):717—726(inChinese).
李昶,臧绍先.2001.岩石圈流变机制转换及华北岩石圈流变性质的研究〔A〕.见:中国地球物理学会年刊2001.昆明:云南科技出版社.242.
LIChang,ZANGShao xian.2001.ThetransitionofrheologicalmechanicsoflithosphereandrheologyofNorthChi na〔A〕.In:AnnualoftheChineseGeophysicalSociety(2001).ScienceandTechnologyPressofYunnanProvince,Kunming.242(inChinese).
马杏垣主编.1989.中国岩石圈动力学地图集〔Z〕.北京:中国地图出版社.
MAXing yuan(Chiefed).1989.LithosphericDynamicsAtlasofChina〔Z〕.ChinaCartographicPublishingHouse,Beijing(inChinese).
史兰斌,林传勇,陈孝德,等.2000.由包体推导的河北汉诺坝下地壳-上地幔地温线及其地质意义〔J〕.地震地质,22(1):37—46.
SHILan bin,LINChuan yong,CHENXiao de.2000.Axenolith derivedgeothermforthelowercrustanduppermantlebeneathHanuobaarea,HebeiProvince,Chinaanditsgeologicimplications〔J〕.SeismologyandGeolo gy,22(1):37—46(inChinese).
石耀霖,朱守彪.2001.从我国震源机制深度变化研究地壳地幔流变特征〔A〕.见:中国地球物理年刊2001.昆明:云南大学出版社.257.
SHIYao lin,ZHUShou biao.2001.ContrastofrheologyofcrustandmantlenearMohorevealedbydepthvariationofearthquakemechanisminChina〔A〕.In:AnnualoftheChineseGeophysicalSociety(2001).ScienceandTechnologyPressofYunnanProvince,Kunming.257(inChinese).孙
武城,徐杰,杨主恩主编.1992.上海奉贤至内蒙古阿拉善左旗地学断面〔Z〕.北京:地震出版社.
SUNWu cheng,XUJie,YANGZhu en(chiefed).1992.GlobalGeoscienceTransect,FengxiantoAlxaZuoqiTransect,China〔Z〕.SeismologicalPress,Beijing(inChinese).
汪洋.1999.中国大陆大地热流分析〔D〕:〔学位论文〕.北京:中国科学院地质研究所.
WANGYang.1999.AnAnalysisfortheContinentalHeatFlowinChina〔D〕.PhDthesis.Instituteofgeology,ChineseAcademyofSciences,Beijing(inChinese).
周永胜,何昌荣.2002.华北地区壳内低速层与地壳流变的关系及其对强震孕育的影响〔J〕.地震地质,24(1):124—132.
ZHOUYong sheng,HEChang rong.2002.TherelationshipbetweenlowvelocitylayersandrheologyofthecrustinnortheastChinaanditseffectonstrongearthquake〔J〕.SeismologyandGeology,24(1):124—132(inChi nese).
AveLallemantHG .1978.Experimentaldeformationofdiopsideandwebsterite〔J〕.Tectonophysics,48(1):1—27.
BaldermanMA .1974.Theeffectofstrainrateandtemperatureontheyieldpointofhydrolyticallyweakenedsyn theticquartz〔J〕.JourGeophysRes,79:1647—1652
.BlacicJD ,ChristleJM .1984.Plasticityandhydrolyticweakeningofquartzsinglecrystals〔J〕.JourGeophyRes,89(B6):4223—4239.
BokelmannGHR ,BerozaGC .2000.Depth dependentearthquakefocalmechanismorientationEvidenceforaweakzoneinthelowercrust〔J〕.JourGeophyRes,105(B9):21683—21695.
BolandJN ,TullisTE .1986.Deformationbehaviorofwetanddryclinopyroxeniteinthebrittletoductiletransitionregion〔A〕.In:HobbsBE ,HeardHC (eds).MineralandRockDeformation:LaboratoryStudies.GeophysMonogr36,AGU ,WashingtonDC .35—50.
BourneSJ ,EnglandPC ,ParsonsB .1998.Themotionofcrustalblocksdrivenbyflowofthelowerlithosphereandimplicationsfor
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