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 we of Urumqi. 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.
出处
《地震学报》
CSCD
北大核心
2009年第1期42-49,共8页
Acta Seismologica Sinica
基金
中国地震局"十五"重点工程"乌鲁木齐城市活断层探测与地震危险性评价"项目(1-4-31)
国家科技支撑计划项目子专题(2006BAC13B010102)
科技部国际合作重点项目"地震危险性评价与地震预报新方法研究(中俄合作)"(2004DFBA0005)资助
关键词
乌鲁木齐
西山断层系
新构造变形
变形机制
Urumqi
Xishan fault system
neotectonic deformation
deforma tion mechanism
