山西断陷带北部块体构造活动样式及强震构造背景
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摘要
应用地块构造几何学方法和原理 ,系统研究了山西断陷带北部构造区地块构造类型、结构和运动特征 .运用断块“多米诺”模型 ,通过断裂构造地貌分析对比 ,系统地讨论了断块变形、断陷盆地伸展运动特点 ,及其区域分布特征 .分析结果显示 :①以北西向断裂划分 ,由西向东分为西区段、中区段和东区段 ,相应的地壳伸展量分别为 4 .4 6km ,2 .80km和1.86km .断块平均伸展量约为 1km .计算结果与实际测量数据大致相同 ;②以恒山断块为界 ,山西断陷带北部构造区可分为南北两区 ,两区地震活动水平不同 ,分别为M≥ 7和 6≤M<7,地震活动表现出明显差异性 .分析认为地震活动的差异性与地块运动方式及特点有关 .北部区断块向NW方向伸展 ,表现出张性地堑式扩展特征 .南部区地块掀斜运动特点 ,地块伸展运动方向向南东 ,与断裂倾向相反 .地块掀斜旋转在断裂上产生附加构造应力 ,这可能是南部区孕育大地震的主要因素之一 .
This paper makes a systematical study on characteristics of structure and motion of the tectonic blocks in northern part of the Shanxi fault depression zone by means of geometrical and kinematical analysis of the blocks. The kinetic behavior of the blocks is discussed by comparing associated geomorphic features of fault movement. All analyses and studies are based on a Domino model. The block movement,fault basin extension and their regional distribution are systematically investigated. ① The study region is divided into subregions by NW striking faults: the western,middle and eastern subregion with crustal extension being 4.46 km,2.80 km and 1.86 km,respectively. The extensional amount of each block in the region is estimated being generally about 1 km. The calculated result using the block motion model approximately fits the data of geologic survey. ② Block kinematical features are obviously different between the northern and southern part,with the Hengshan block in between,of the study region. Moreover,the magnitude of the largest historical earthquake in the northern part is about 6,while that in the southern is 7. The faulted blocks in the northern subregion show northwestward extension,indicating a feature of extensional graben,while the blocks in the southern part manifest tilt motion,extending southeastward,in the opposite sense of fault dipping. Additional tectonic stress generated by block rotation may be one of major factors affecting seismogenic process in the region. It is responsible for the difference in the movement of the block boundary faults and seismic activities between the two subregions.
This paper makes a systematical study on characteristics of structure and motion of the tectonic blocks in northern part of the Shanxi fault depression zone by means of geometrical and kinematical analysis of the blocks. The kinetic behavior of the blocks is discussed by comparing associated geomorphic features of fault movement. All analyses and studies are based on a Domino model. The block movement,fault basin extension and their regional distribution are systematically investigated. ① The study region is divided into subregions by NW striking faults: the western,middle and eastern subregion with crustal extension being 4.46 km,2.80 km and 1.86 km,respectively. The extensional amount of each block in the region is estimated being generally about 1 km. The calculated result using the block motion model approximately fits the data of geologic survey. ② Block kinematical features are obviously different between the northern and southern part,with the Hengshan block in between,of the study region. Moreover,the magnitude of the largest historical earthquake in the northern part is about 6,while that in the southern is 7. The faulted blocks in the northern subregion show northwestward extension,indicating a feature of extensional graben,while the blocks in the southern part manifest tilt motion,extending southeastward,in the opposite sense of fault dipping. Additional tectonic stress generated by block rotation may be one of major factors affecting seismogenic process in the region. It is responsible for the difference in the movement of the block boundary faults and seismic activities between the two subregions.
引文
程绍平,杨桂枝.1996.大同阳原盆地南缘断裂带的晚第四纪分段和构造地貌变异[J].地震地质,18(4):289～299
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国家地震局“鄂尔多斯周缘断裂系”课题组.1988.鄂尔多斯周缘活动断裂系[M].北京:地震出版社,70～107
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徐锡伟.1986.山西系舟山西麓断裂右旋错动证据的发现和全新世的滑动速率[J].地震地质,8(3):44～46
徐锡伟.1990.剪切带尾端张性区构造扩展的模拟实验及其地震危险性分析[J].华北地震科学,8(3):40～46
徐锡伟,米仓伸之,铃木康弘,等.1996.山西六棱山北麓晚第四纪不规则断裂作用的地貌学研究[J].地震地质,18(2):169～181
申旭辉,汪一鹏.1995.1926年灵丘地震烈度分布特征与阻震构造初步研究[J].华北地震科学,13(1):9～16
徐锡伟.2002.首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,43～104
张之立,方兴,阎红,等.1987.山西地堑系形成的力学模式及山西地震带的特点[J].地震学报,9(1):28～36
BosworthW .1985.Discussiononthestructuralevolutionofextensionalbasinmargins[J].JGeolSocLond,142～148
ZhangYue.Qiao,JacquesLouisMercier,PierreVergely.1998.ExtensioninthegrabensystemsaroundtheOrdos(China),anditscontributiontotheextrusiontectonicsofsouthChinawithrespecttoGobiMongolia[J].Tectonophysics,285:41～75
邓起东,王克鲁,汪一鹏,等.1973.山西隆起区断陷地震带地震地质条件及地震发展趋势概述[J].地质科学,(1):37～47
邓起东,尤惠川.1985.鄂尔多斯周缘断陷带的构造活动特征及其形成机制[A].现代地壳运动研究,1[M].北京:地震出版社,58～87
邓起东,米仓伸之,徐锡伟,等.1994.山西高原六棱山北麓断裂晚第四纪运动学特征初步研究[J].地震地质,16(4):339～342
段瑞涛,方仲景.1995.六棱山北麓断裂新活动特征[J].地震地质,17(3):207～213
窦素芹,于慎谔,刘光勋,等.1995.系舟山山前活动断裂的几何结构及其活动性[A].活动断裂研究(4)[M].北京:地震出版社,104～115
方仲景,程绍平,冉永康,等.1993.延怀盆地构造及其晚第四纪断裂活动的某些特征[J].地球物理学进展,8(4):265～266
国家地震局“鄂尔多斯周缘断裂系”课题组.1988.鄂尔多斯周缘活动断裂系[M].北京:地震出版社,70～107
卢演俦,丁国喻,等.1985.地块相对运动与鄂尔多斯地块周缘、第四纪断陷盆地[J].中国第四纪研究,(2):124～131
刘巍,孟雁英,王赵丽.1995.大同盆地现今构造活动及地壳应力场特征[J].山西地震,(1):7～13
刘光勋,于慎谔,张世民,等.1991.山西五台山北麓活动断裂带[A].活动断裂研究,1[C].北京:地震出版社,118～130
冉永康,方仲景,李志义,等.1991.怀来涿鹿盆地周缘的活动断裂及其基本特征[A].活动断裂研究,1[C].北京:地震出版社,140～155
徐锡伟.1986.山西系舟山西麓断裂右旋错动证据的发现和全新世的滑动速率[J].地震地质,8(3):44～46
徐锡伟.1990.剪切带尾端张性区构造扩展的模拟实验及其地震危险性分析[J].华北地震科学,8(3):40～46
徐锡伟,米仓伸之,铃木康弘,等.1996.山西六棱山北麓晚第四纪不规则断裂作用的地貌学研究[J].地震地质,18(2):169～181
申旭辉,汪一鹏.1995.1926年灵丘地震烈度分布特征与阻震构造初步研究[J].华北地震科学,13(1):9～16
徐锡伟.2002.首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,43～104
张之立,方兴,阎红,等.1987.山西地堑系形成的力学模式及山西地震带的特点[J].地震学报,9(1):28～36
BosworthW .1985.Discussiononthestructuralevolutionofextensionalbasinmargins[J].JGeolSocLond,142～148
ZhangYue.Qiao,JacquesLouisMercier,PierreVergely.1998.ExtensioninthegrabensystemsaroundtheOrdos(China),anditscontributiontotheextrusiontectonicsofsouthChinawithrespecttoGobiMongolia[J].Tectonophysics,285:41～75
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