乌鲁木齐西山断层系的新构造变形特征与机制
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摘要
通过对西山断层系详细地追踪考察和系列探槽的开挖,并结合深部探测资料进行了综合分析,认为晚第四纪以来,在近NS向的挤压应力作用下,西山块体不断向南侧天山山体方向发展,总体表现为向南的逆冲滑移和地壳缩短.其南侧的主控边界断裂——西山断层的新活动性主要表现为向南的逆冲.西山断层北侧的王家沟断层组和九家湾断层组是与西山断层具有成因联系的次级断层,均为伴随西山隆起形成的顺层滑动断层.但九家湾断层组明显受到博格达推覆体系的影响,是局部拉张应力下产生的正断层.这两组断层吸收转换了西山断层上盘的褶皱变形量,因而西山断隆表现为明显的单斜特征.西山断层系的各条次级断层属于同一发震构造体系,其大震的地震危险性应该合并考虑.
The Xishan fault system is a very important fault zone in western area of rümqi.It consists of 9 secondary faults with different length and activity.Based on detail investigation,geological mapping,some large-scale trenching and the result of deep seismic reflection,we have achieved important progress and gained new knowledge on the neotectonic deformation and its mechanism of the Xishan fault system.The Xishan block extruded southward to the Tianshan mountain because of the compressive force in nearly N--S direction since late Quaternary.The Xishan fault controlling southern boundary of the Xishan block is a southward thrusting fault.The Wangjiagou fault group and the Jiujiawan fault group are all secondary faults relative to the Xishan fault.They are all bedding-plane faults,but the fracture style is different.The Wangjiagou fault group consists of thrust faults,but the Jiujiawan fault group is a tensional normal fault zone.The Wangjiagou fault group and the Jiujiawan fault group absorbed the folding deformation of the Xishan block.The compressive deformation released in movement of dislocation,so the hang-wall of the Xishan fault is obviously a monoclinal structure,rather than folding.The Xishan fault system converges on the detachment surface at about 10 km depth.The seismic risk of the fault system should be assessed together.
The Xishan fault system is a very important fault zone in western area of rümqi.It consists of 9 secondary faults with different length and activity.Based on detail investigation,geological mapping,some large-scale trenching and the result of deep seismic reflection,we have achieved important progress and gained new knowledge on the neotectonic deformation and its mechanism of the Xishan fault system.The Xishan block extruded southward to the Tianshan mountain because of the compressive force in nearly N--S direction since late Quaternary.The Xishan fault controlling southern boundary of the Xishan block is a southward thrusting fault.The Wangjiagou fault group and the Jiujiawan fault group are all secondary faults relative to the Xishan fault.They are all bedding-plane faults,but the fracture style is different.The Wangjiagou fault group consists of thrust faults,but the Jiujiawan fault group is a tensional normal fault zone.The Wangjiagou fault group and the Jiujiawan fault group absorbed the folding deformation of the Xishan block.The compressive deformation released in movement of dislocation,so the hang-wall of the Xishan fault is obviously a monoclinal structure,rather than folding.The Xishan fault system converges on the detachment surface at about 10 km depth.The seismic risk of the fault system should be assessed together.
引文
邓起东,冯先岳,张培震,徐锡伟,杨晓平,彭斯震,李军.2000.天山活动构造[M].北京:地震出版社:42-48.
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高国英,曲延军.1998.乌鲁木齐地区构造应力场与中强地震活动特征延军[J].内陆地震,12(4):296-303.
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沈军,宋和平.2008.乌鲁木齐城市活断层探测与地震危险性评价主要成果简介[J].地震地质,30(1):273-288.
张红艳,谢富仁,崔效峰,杜义,舒塞兵.2006.乌鲁木齐地区活动断层滑动与现代构造应力场[J].中国地震,22(3):259-268.
张培震,邓起东,杨晓平,冯先岳,彭斯震,赵瑞斌.1995.天山北麓的冰水冲洪积地貌与新构造运动[G]∥国家地震局地质研究所编.活动断裂研究(4).北京:地震出版社:63-78.
高存海,刘嘉麒.1990.乌鲁木齐河流域的黄土研究[J].第四纪研究,(3):251-260.
高国英,曲延军.1998.乌鲁木齐地区构造应力场与中强地震活动特征延军[J].内陆地震,12(4):296-303.
韩淑媞,叶玮.1985.乌鲁木齐仓房沟晚更新世沉积环境[G]∥新疆大学编.干旱区新疆第四纪研究论文集.乌鲁木齐:新疆人民出版社:21-23.
刘保金,沈军,张先康,陈颙,方盛明,宋和平,酆少英,赵成斌.2007.深地震反射剖面揭示出的天山北缘乌鲁木齐坳陷地壳结构和构造[J].地球物理学报,50(5):1464-1472.
龙海英,高国英,聂晓红,李莹甄.2007.乌鲁木齐地区中小地震震源机制解及构造应力场[J].地震,27(3):89-96.
乔作山.1981.乌鲁木齐河头屯河流域第四纪地层概要[G]∥新疆第四纪地质及冰川地质论文选集.乌鲁木齐:新疆人民出版社:176-183.
冉勇康,陈立春,沈军,李军,宫会玲.2007.乌鲁木齐西山断裂组与地表破裂型逆断层古地震识别标志[J].地震地质,29(2):218-235.
沈军,宋和平,李军.2007.乌鲁木齐城市活断层发震构造模型初探[J].内陆地震,21(3):193-204.
沈军,宋和平.2008.乌鲁木齐城市活断层探测与地震危险性评价主要成果简介[J].地震地质,30(1):273-288.
张红艳,谢富仁,崔效峰,杜义,舒塞兵.2006.乌鲁木齐地区活动断层滑动与现代构造应力场[J].中国地震,22(3):259-268.
张培震,邓起东,杨晓平,冯先岳,彭斯震,赵瑞斌.1995.天山北麓的冰水冲洪积地貌与新构造运动[G]∥国家地震局地质研究所编.活动断裂研究(4).北京:地震出版社:63-78.
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