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  李明,张世民,姜大伟,梁宽.龙门山中北段流域地貌特征及其构造意义[J].震灾防御技术,2019,14(3):640-651, DOI:10.11899/zzfy20190316.

龙门山中北段流域地貌特征及其构造意义
摘要:    龙门山中北段位于青藏高原东缘,该区作为高原向东扩展的前缘部位,其地形与河流水系的演化记录了高原隆升与挤压扩展及其气候环境效应的各种信息。龙门山中北段构造活动有明显差异,从中段逆冲为主转化为北段的走滑为主,本文采用定量化地貌参数从构造地貌的角度揭示了区域构造活动的差异。龙门山中北段地貌因子(坡度、地形起伏度和条带状剖面)的阶梯状分布特点,显示了高原扩展的逆冲推覆特征,在中央断裂处构造抬升作用最强,同时显示出了南北向构造活动减弱的趋势,由中段的逆冲转换为北段逆冲兼走滑的形式。北川-映秀断裂两侧流域的HI值也显示了断裂上盘高、下盘低、沿走向减弱的趋势。综合分析认为,本区构造活动是地貌演化的主控因素,龙门山中北段地形存在差异,北川-映秀断裂两侧的小流域地貌指数分析显示,构造抬升活动自南向北减弱,中段以逆冲为主,北段为逆冲兼走滑。
作者单位
李明 中国地震局地壳应力研究所, 地壳动力学重点实验室, 北京 100085 
张世民 中国地震局地壳应力研究所, 地壳动力学重点实验室, 北京 100085 
姜大伟 中国地震局地壳应力研究所, 地壳动力学重点实验室, 北京 100085 
梁宽 中国地震局地壳应力研究所, 地壳动力学重点实验室, 北京 100085 
关  键  词:坡度  地形起伏度  HI  构造活动
DOI:10.11899/zzfy20190316
基金项目:国家自然科学基金(41802226),中国地震局地壳应力研究所中央级公益性科研院所基本科研业务专项(ZDJ 2018-03)
收稿日期:2019-01-22
作者简介:李明,男,生于1993年。硕士研究生。主要从事构造地貌和活动构造方面研究。E-mail:limingwayne@163.com
通讯作者:张世民,男,生于1965年。研究员。主要从事地震地质、第四纪地质和城市活断层方面研究。E-mail:zhangshimin@263.net
Geomorphic Features and Tectonic Significance of the Middle and North Section of Longmenshan
Abstract:      The study of Quantitative geomorphological parameters is a common means of tectonic geomorphology for regional tectonic activities and their evolution. The middle and northern sections of the Longmenshan are located on the eastern margin of the Qinghai-Tibet plateau as the frontier part of the plateau expanding eastward. The evolution of the topography and river system in this area records abundant information about plateau uplift and extrusion expansion and its climatic environmental effects. The stepped distribution characteristics of the geomorphic factors (slope, topographic relief, swath profiles) in the middle and northern sections of the Longmenshan suggest the thrusting characteristics of the plateau expansion. The tectonic uplift is the strongest at the central fault and shows the tendency of the tectonic activity to weaken from north and south which is converted from the thrust of the middle section to the form of the thrust and strike slip of the northern section. The HI value of the basin on both sides of the Beichuan-Yingxiu fault also shows that the hanging wall of the fracture is relatively high. Based on the comprehensive analysis, the tectonic activities in this area are the main controlling factors of geomorphological evolution. There are differences in the topography of the middle and northern sections of Longmenshan. The geomorphological index analysis of the small watersheds on both sides of the Beichuan-Yingxiu fault shows that the tectonic uplifting activity is weakened from south to north, and the middle section is reversed. Mainly, the northern section is thrust with strike-slip component.
Keywords:  Slope  Relief  HI value  Tectonic activity
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