青藏高原东北部天然地震探测与岩石圈深部特征
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摘要
为了研究青藏高原东北部块体构造变形的深部驱动机制 ,笔者对青藏高原东北部的天然地震观测数据进行地震层析反演 ,并结合同一剖面的接收函数及各向异性结果进行讨论。介绍了ACH方法的基本原理 ,论述了由于印度板块向北俯冲的强大的持续作用力 ,造就了NE向俯冲到柴达木盆地之下的昆仑造山带 ,并发现在巴颜喀拉地体下方壳幔内的仰冲活动。壳幔内的低速体十分显著地出现在阿尼玛卿缝合线以北 ,深度可达 30 0km。推断该低速体可能与昆仑断裂在深层的剪切作用有关。深部资料显示该区莫霍界面由北向南逐渐加深 ,这与青藏高原东北部的岩石圈减薄现象一致 ,而且与印度板块向北运动的远程效应有关。另外 ,地震层析结果及各向异性分析也支持青藏高原东北部主应力方向转为NE向的观点。
To better understand the driving mechanism in depth controlling deformation across the blocks in the northeast part of the Qinghai-Tibetan Plateau, the authors gave some tomographic analysis on the teleseismic data recorded in the area, and the results on receiver function and anisotropy of the same area are discussed in combination. The ACH basics is introduced. It is suggested that the Kunlun orogeny, driven by the continuing northward movement of the Indian plate,is induced underthrust northeastward beneath the Qaidam basin, and a south-dipping ramp is observed in the upper mantle under the Bayan Har block. Low velocity zones (LVZ) in the upper mantle appear well defined to the north of Animaqin Suture, reaching as deep as 300 km. The LVZs are presumably associated with the shearing at a deeper level of Kunlun fault. The velocity image reveals that Moho deepens southward in the study area, which is in consistency with the lithospheric thinning trend in the northeastern Tibetan Plateau. This is believed to be the so-called Remote Effect of the northward motion of India. In addition, the tomographic and anisotropic analysis seems to support the arguement that the main strain turns from northward to northeastward in the northeastern Tibetan Plateau.
To better understand the driving mechanism in depth controlling deformation across the blocks in the northeast part of the Qinghai-Tibetan Plateau, the authors gave some tomographic analysis on the teleseismic data recorded in the area, and the results on receiver function and anisotropy of the same area are discussed in combination. The ACH basics is introduced. It is suggested that the Kunlun orogeny, driven by the continuing northward movement of the Indian plate,is induced underthrust northeastward beneath the Qaidam basin, and a south-dipping ramp is observed in the upper mantle under the Bayan Har block. Low velocity zones (LVZ) in the upper mantle appear well defined to the north of Animaqin Suture, reaching as deep as 300 km. The LVZs are presumably associated with the shearing at a deeper level of Kunlun fault. The velocity image reveals that Moho deepens southward in the study area, which is in consistency with the lithospheric thinning trend in the northeastern Tibetan Plateau. This is believed to be the so-called Remote Effect of the northward motion of India. In addition, the tomographic and anisotropic analysis seems to support the arguement that the main strain turns from northward to northeastward in the northeastern Tibetan Plateau.
引文
董英君,薛光琦,马开义,姜枚.1999.阿尔金断裂带各向异性研究.地球物理学进展,14(4):58～64.
丁志峰,曾融生.1996.青藏高原横波分裂的观测研究.地球物理学报,39(2):211～219.
高锐,成湘州,丁谦.1985.格尔木-额济纳旗地学断面地球动力学模型初探.地球物理学报,38(增刊Ⅱ):3～114.
姜枚,吕庆田,史大年,薛光琦等.1996.用天然地震探测青藏高原中部地壳、上地幔结构.地球物理学报,39(4):470～482.
姜枚,AHirn,薛光琦,董英君,钱辉,GPorpinet,GWittlinger.1999.青藏高原地震剪切波各向异性特征及解释.现代地质,13(增刊):56～60.
姜枚,许志琴,AHirn,刘妍,董英君.2001.青藏高原及其部分邻区地震各向异性和上地幔特征.地球学报,22(2):111～116.
李松林,张先康,张成科等.2002.玛沁兰州靖边地震测深剖面地壳速度结构的初步研究.地球物理学报,45(2):211～217.
钱辉,姜枚,薛光琦等.2001.天然地震接收函数所揭示的青藏高原东部的地壳结构.地震学报,23(1):103～108.
史大年,姜枚,马开义,薛光琦,董英君.1999.阿尔金断裂带地壳和上地幔结构的P波层析成像.地球物理学报,42(3):342～349.
魏素花,薛光琦,钱辉,姜枚,GPorpinet,EdiKissling.2000.新疆库车克拉玛依地震层析成像.地球物理学进展,15(4):46～54.
王有学,钱辉.2000.青海东部地壳速度结构特征研究.地学前缘,7(4):568～578.
薛光琦,姜枚,史大年,宿和平.1999.利用接收函数探讨阿尔金地区深部构造.地质评论,45(2):120～124.
许志琴,杨经绥,姜枚.2001.青藏高原北部的碰撞造山及深部动力学.地球学报,22(1):5～11.
许志琴,杨经绥,姜枚,李海兵.1999.大陆俯冲作用及青藏高原周边造山带的崛起.地学前缘,6(3):139～151.
胥颐,刘福田,刘建华,孙若昧,何建坤.2000.中国大陆西北造山带及其毗邻盆地的地震层析成像.中国科学,30(2):113～122.
朱介寿,曹家敏,李显贵.1997.中国及其邻区地球三维初始模型的建立.地球物理学报,40(5):627～648.
张培震,王琪.2001.中国大陆现今地壳运动和构造变形.现代地壳运动与地球动力学研究,北京:地震出版社,21～35.
AkiK ,ChristofferssonA ,HusebyeES .1977.Determinationofthethree dimensionalseismicstructureofthelithosphere,J.Geophy.Res.,82(2):277～296.
BourjorL ,RomanowiczB .1992.CrustanduppermantletomographyinTibetusingsurfacewaves.Geophy.Res.Lett.,19:881～889.
DingZhifeng,ZengRongsheng.1996.ObservationandstudyofshearwaveanistropyinTibetanplateau.ActaGeophysicaSinica,39(2):211～219(inChinesewithEnglishabstract).
DongYinjun,XueGuangqi,MaKaiyi,JiangMei.1999.StudiesonsharewaveanisotropybeneathaltynfaultsystemanditsAdjacentarea.ProgressinGeophysics,14(4):58～64.
EvansJR ,AchauerU .1993.TeleseismicvelocitytomographyusingtheACHmethod:theoryandapplicationtocontinental scaleatudies.In:IyerHM ,HiraharaKed.Seimictomography:TheoryandPractice,309～360.
EnglandP ,HousemanG .1989.Extensionduringcontinentalconver gence,withapplicationtotheTibetanplateau.J .Geophy.Res.,94:17561～17579.
GaoRui,ChengXiangzhou,DingQian.1995.PreliminartgeodynamicmodelofGolmud—EjinQigeosciencetransect.ActaGeophysicaSinica,38(Sup.Ⅱ):3～114(inChinese).
GerardWittlinger,FredericMasson.1996.Georgespoupinet,seismicto mographyofnorthernTibetandKunlun:evidenceforcrustalblocksandmantlevelocitycontrasts.EPSL ,139,263～279.
HirnA .1994.ResultsoftheFrenchresearchinHimalayaTibetKarakoruminthefieldofseismologyappliedtodeepstructure:pre sentdaydeepseismologicalstructureandtheevolutionofHimalayaTibet,FrenchEarthSciencesinHimalayaRegions,PublishedbyAllianceFrancaise,81～90.
LiSonglin,ZhangXiankang,ZhangChengke.2002.ApreliminarystudyonthecrustalvelocitystructureofMaqinLanzhouJingbianbymeansofdeepseismicsoundingprofile.ActaGeophysicaSinica,45(2):211～217(inChinesewithEnglishabstract).
JiangMei,LuQingtian,ShiDanian,XueGuangqi.1996.TheStudyonthestructureofcrustanduppermantlewithnaturalearthquakesincentralTibetanplateau,ChineseJournalofGeophysics,39(4):470～482(inChinesewithEnglishabstract).
JiangMei,AHirn,XueGuangqi,DongYingjun,QianHui,GPoupinet,GWittlinger.1999.CharacteristicsofsharewaveanisotropyinTi betanplateauanditsinterpretation.Geoscience,13(Sup.)56～60(inChinesewithEnglishabstract).
JiangMai,XuZhiqin,AHirn,LiuYan,DongYingjun.2001.TeleseismicanisotropyandcorrespondingfeaturesofupperMantleinTibetplateauanditsNeighboringAreas.ActaGeoscientiaSinica,22(2):111～116(inChinesewithEnglishabstract).
PaulTapponnier,XuZhiqin,FrancoiseRoger,BertrandMeyer,Nico lasArnaud,G啨rardWittlinger,YangJingsui.2001.Obliquestep wiseriseandgrowthoftheTibetplateau.Scienc
丁志峰,曾融生.1996.青藏高原横波分裂的观测研究.地球物理学报,39(2):211～219.
高锐,成湘州,丁谦.1985.格尔木-额济纳旗地学断面地球动力学模型初探.地球物理学报,38(增刊Ⅱ):3～114.
姜枚,吕庆田,史大年,薛光琦等.1996.用天然地震探测青藏高原中部地壳、上地幔结构.地球物理学报,39(4):470～482.
姜枚,AHirn,薛光琦,董英君,钱辉,GPorpinet,GWittlinger.1999.青藏高原地震剪切波各向异性特征及解释.现代地质,13(增刊):56～60.
姜枚,许志琴,AHirn,刘妍,董英君.2001.青藏高原及其部分邻区地震各向异性和上地幔特征.地球学报,22(2):111～116.
李松林,张先康,张成科等.2002.玛沁兰州靖边地震测深剖面地壳速度结构的初步研究.地球物理学报,45(2):211～217.
钱辉,姜枚,薛光琦等.2001.天然地震接收函数所揭示的青藏高原东部的地壳结构.地震学报,23(1):103～108.
史大年,姜枚,马开义,薛光琦,董英君.1999.阿尔金断裂带地壳和上地幔结构的P波层析成像.地球物理学报,42(3):342～349.
魏素花,薛光琦,钱辉,姜枚,GPorpinet,EdiKissling.2000.新疆库车克拉玛依地震层析成像.地球物理学进展,15(4):46～54.
王有学,钱辉.2000.青海东部地壳速度结构特征研究.地学前缘,7(4):568～578.
薛光琦,姜枚,史大年,宿和平.1999.利用接收函数探讨阿尔金地区深部构造.地质评论,45(2):120～124.
许志琴,杨经绥,姜枚.2001.青藏高原北部的碰撞造山及深部动力学.地球学报,22(1):5～11.
许志琴,杨经绥,姜枚,李海兵.1999.大陆俯冲作用及青藏高原周边造山带的崛起.地学前缘,6(3):139～151.
胥颐,刘福田,刘建华,孙若昧,何建坤.2000.中国大陆西北造山带及其毗邻盆地的地震层析成像.中国科学,30(2):113～122.
朱介寿,曹家敏,李显贵.1997.中国及其邻区地球三维初始模型的建立.地球物理学报,40(5):627～648.
张培震,王琪.2001.中国大陆现今地壳运动和构造变形.现代地壳运动与地球动力学研究,北京:地震出版社,21～35.
AkiK ,ChristofferssonA ,HusebyeES .1977.Determinationofthethree dimensionalseismicstructureofthelithosphere,J.Geophy.Res.,82(2):277～296.
BourjorL ,RomanowiczB .1992.CrustanduppermantletomographyinTibetusingsurfacewaves.Geophy.Res.Lett.,19:881～889.
DingZhifeng,ZengRongsheng.1996.ObservationandstudyofshearwaveanistropyinTibetanplateau.ActaGeophysicaSinica,39(2):211～219(inChinesewithEnglishabstract).
DongYinjun,XueGuangqi,MaKaiyi,JiangMei.1999.StudiesonsharewaveanisotropybeneathaltynfaultsystemanditsAdjacentarea.ProgressinGeophysics,14(4):58～64.
EvansJR ,AchauerU .1993.TeleseismicvelocitytomographyusingtheACHmethod:theoryandapplicationtocontinental scaleatudies.In:IyerHM ,HiraharaKed.Seimictomography:TheoryandPractice,309～360.
EnglandP ,HousemanG .1989.Extensionduringcontinentalconver gence,withapplicationtotheTibetanplateau.J .Geophy.Res.,94:17561～17579.
GaoRui,ChengXiangzhou,DingQian.1995.PreliminartgeodynamicmodelofGolmud—EjinQigeosciencetransect.ActaGeophysicaSinica,38(Sup.Ⅱ):3～114(inChinese).
GerardWittlinger,FredericMasson.1996.Georgespoupinet,seismicto mographyofnorthernTibetandKunlun:evidenceforcrustalblocksandmantlevelocitycontrasts.EPSL ,139,263～279.
HirnA .1994.ResultsoftheFrenchresearchinHimalayaTibetKarakoruminthefieldofseismologyappliedtodeepstructure:pre sentdaydeepseismologicalstructureandtheevolutionofHimalayaTibet,FrenchEarthSciencesinHimalayaRegions,PublishedbyAllianceFrancaise,81～90.
LiSonglin,ZhangXiankang,ZhangChengke.2002.ApreliminarystudyonthecrustalvelocitystructureofMaqinLanzhouJingbianbymeansofdeepseismicsoundingprofile.ActaGeophysicaSinica,45(2):211～217(inChinesewithEnglishabstract).
JiangMei,LuQingtian,ShiDanian,XueGuangqi.1996.TheStudyonthestructureofcrustanduppermantlewithnaturalearthquakesincentralTibetanplateau,ChineseJournalofGeophysics,39(4):470～482(inChinesewithEnglishabstract).
JiangMei,AHirn,XueGuangqi,DongYingjun,QianHui,GPoupinet,GWittlinger.1999.CharacteristicsofsharewaveanisotropyinTi betanplateauanditsinterpretation.Geoscience,13(Sup.)56～60(inChinesewithEnglishabstract).
JiangMai,XuZhiqin,AHirn,LiuYan,DongYingjun.2001.TeleseismicanisotropyandcorrespondingfeaturesofupperMantleinTibetplateauanditsNeighboringAreas.ActaGeoscientiaSinica,22(2):111～116(inChinesewithEnglishabstract).
PaulTapponnier,XuZhiqin,FrancoiseRoger,BertrandMeyer,Nico lasArnaud,G啨rardWittlinger,YangJingsui.2001.Obliquestep wiseriseandgrowthoftheTibetplateau.Scienc
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