乌鲁木齐城市活断层发震构造模型初探
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摘要
根据地表活断层资料、深地震反射剖面资料、石油地震剖面资料、流动地震观测和小震精确定位资料,通过与北天山山前典型发震构造的对比及逆断裂-褶皱与推覆构造的基本结构特征,初步建立了乌鲁木齐目标区发震构造模型。乌鲁木齐目标区可分为2个主要的地震构造,它们均是逆冲推覆构造。西侧为北天山山前逆冲推覆构造,由根部逆断裂、中部滑脱面和前缘挤压褶皱隆起带组成,根部逆断裂及前缘挤压褶皱带上发育全新世活断层,滑脱构造具有自南向北扩展的特点,未来的7级强震可能发生在根部断裂附近,而前缘挤压褶皱隆起构造,即西山隆起及其相伴生的西山断层和王家沟断层组、九家湾断层组,不具备发生大于6.5级地震的条件。东侧为博格达弧形推覆构造的西翼,其发震构造也由根部逆断层、中部滑脱层和前缘挤压褶皱隆起带组成,推覆构造具有自南向北扩展的特点。现今的推覆体前缘为阜康南断裂和古牧地背斜。该推覆构造带内部的雅玛里克断层、白杨南沟断层、碗窑沟断层和八钢-石化断裂,不是全新世活动断层,不具备发生大于6.5级地震的条件。
The seismogenic tectonic model in Urumqi city was proposed in this paper,it is according to the data of geology research along the active fault,the results of the deep seismic reflection,the petroleum seismic profiles,the observation of seismic array and fine location of the small earthquakes,as well as analyses of the basic features of the thrust tectonics and nappe along the piedmont of northern Tianshan,China.There are two major seismogenic tectonics around Urumqi city,they are all overthrust tectonics.The west seismogenic tectonic is the foreland overthrust tectonic of northern Tianshan,it is composed of three sections,the first section is reverse fault on the foot,the second section is detachment interface in the middle,the third section is folding uplift belt on the top; Holocene active faults are developed in the first and third sections,and the detachment interface expand from south to north;The MS7earthquakes in future can occur in the first section,while MS≥6.5 earthquakes in future can not occur in the third section,for example Xishan fault,Wangjiagou faults group and Jiujiawan faults group.The east seismogenic tectonic is the western part of Bogda arcuate structure,it is similar with west seismogenic tectonic;Nowadays,Fukang southern fault and Gumudi anticline in the foreland of nappe,Yamalike fault,South Baiyanggou fault,Wanyaogou fault and Bagang-Shihua fault in the nappe are not holocene active faults,MS≥6.5 earthquakes in future can not occur in that place.
The seismogenic tectonic model in Urumqi city was proposed in this paper,it is according to the data of geology research along the active fault,the results of the deep seismic reflection,the petroleum seismic profiles,the observation of seismic array and fine location of the small earthquakes,as well as analyses of the basic features of the thrust tectonics and nappe along the piedmont of northern Tianshan,China.There are two major seismogenic tectonics around Urumqi city,they are all overthrust tectonics.The west seismogenic tectonic is the foreland overthrust tectonic of northern Tianshan,it is composed of three sections,the first section is reverse fault on the foot,the second section is detachment interface in the middle,the third section is folding uplift belt on the top; Holocene active faults are developed in the first and third sections,and the detachment interface expand from south to north;The MS7earthquakes in future can occur in the first section,while MS≥6.5 earthquakes in future can not occur in the third section,for example Xishan fault,Wangjiagou faults group and Jiujiawan faults group.The east seismogenic tectonic is the western part of Bogda arcuate structure,it is similar with west seismogenic tectonic;Nowadays,Fukang southern fault and Gumudi anticline in the foreland of nappe,Yamalike fault,South Baiyanggou fault,Wanyaogou fault and Bagang-Shihua fault in the nappe are not holocene active faults,MS≥6.5 earthquakes in future can not occur in that place.
引文
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[4]邓起东,冯先岳,张培震,等.天山活动构造[M].北京:地震出版社,2002.
[5]汪一鹏,沈军.天山北麓活动构造基本特征[J].新疆地质,2000,18(3):203-210.
[6]伍致中,韩富贤.再论博格迭推疆构造与油气[J].新疆地质,1991,9(1):40-49.
[7]李学义.准噶尔南缘复杂构造几项解释技术的应用[J].新疆石油学院学报,2002,15(1):5-10.
[8]李学义,刘楼军,陈伟.准噶尔南缘古牧地构造建模分析[J].新疆石油地质,2004,25(2):141-142.
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