基于地貌参数的色尔腾山山前断裂相对构造活动性研究

Relative tectonic activity of the Sertengshan piedmont fault based on geomorphic parameters

摘要:

色尔腾山山前断裂为全新世活动断裂,近年来相关研究主要包括色尔腾山山前断裂不同分段的滑动速率和古地震的探究。提取色尔腾山山前断裂区域河流地貌参数,获取区域28条河流的纵剖面、面积-高程积分与陡峭指数。结果显示,大多数河流纵剖面用指数函数拟合效果较好,指示流域大部分处于壮年期。面积-高程积分值HI位于0.35~0.66之间。12个流域HI大于0.5,处于幼年期;16个流域HI在0.3~0.5范围内,为壮年期阶段。降水和岩性对陡峭指数的影响有限,构造隆升速率是陡峭指数的主要控制因素。沿着断裂带,河段陡峭指数高值呈现增加-降低-增加-降低-低缓的趋势。整体上,色尔腾山山前断裂带构造运动相对活跃,且西部和中部大于东部,断裂带西部和断裂走向转折处构造活动性较强,与前人对构造活动性分布特征的研究结果相对一致。

Abstract:

The Sertengshan piedmont fault was active in the Holocene. Recent studies have mainly explored the paleoearthquakes and the slip rate in different segments. This paper extracted the river geomorphic parameters in the Sertengshan piedmont fault area, thus obtaining the longitudinal profile, hypsometric integral (HI), and normalized channel steepness index of 28 rivers. Results indicate that the longitudinal profiles of most rivers are well-fitted by an exponential function, indicating that most of the basins are in their prime years. The HI values range from 0.35 to 0.66, in which 12 basins are in the juvenile stage with HI greater than 0.5, and 16 basins are in the prime stage with HI in the range of 0.3-0.5. The precipitation and lithology reveal limited influence on the steepness index, while the steepness index is principally affected by the tectonic uplift rate. Along the fault zone, high values of the steepness index in each channel show an increasing-decreasing-increasing-decreasing-slowing trend. Overall, the tectonic movement of the Sertengshan piedmont fault zone is relatively active, with the western and central parts being more active than the eastern part. Furthermore, the tectonic activity in the western part of the fault zone and the transition of fault strike is strong, which is almost consistent with the distribution characteristics of structural activities presented in previous studies.