[an error occurred while processing this directive] 高校地质学报 2020, 26(3) 339-349 DOI:   10.16108/j.issn1006-7493.2019036  ISSN: 1006-7493 CN: 32-1440/P

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本文关键词相关文章
河道纵剖面
裂点
岷江
地震滑坡
青藏高原东缘
本文作者相关文章
刘譞
林舟
丁超
PubMed
Article by Liu X
Article by Lin Z
Article by Ding C
岷江上游流域裂点分布及成因分析
刘譞,林舟,丁超
浙江大学 地球科学学院,杭州 310012
摘要: 均衡状态时的基岩河道纵剖面表现为平滑形态,然而自然界的河道纵剖面常因地球各种内外动力作用的影响而呈现出以裂点为特征的不均衡状态,因此不均衡的河道剖面及裂点的特征可以用于指示外界环境的扰动。位于青藏高原东缘造山带的岷江上游流域水系普遍呈现不均衡的特征,且广泛发育有裂点。文章基于数字高程模型,提取裂点空间分布特征,通过裂点成因分析后发现,这些裂点的形成受到岩性、冰川作用、构造等因素的影响:因岩性形成的裂点主要位于花岗岩与其他地层的交界线上;而高海拔裂点主要受到冰川作用的控制,位于地形起伏度较低的区域;流域内低海拔区域成层分布的坡断型裂点可能主要因多期次区域构造隆升而形成;岷江上游下段流域的阶梯状垂阶型裂点则主要因地震滑坡形成。这一结果增进了对岷江流域的河流地貌发育及其影响因素的理解。此外,研究结果也说明在对河道纵剖面分析时有必要更多考虑到滑坡及冰川等因素对现代河道纵剖面产生的重要影响,为进一步理解造山带地貌演化及控制因素提供了参考视角。
关键词 河道纵剖面   裂点   岷江   地震滑坡   青藏高原东缘  
Distribution and Causes of Knickpoints in the Upper Reaches of Minjiang River
LIU Xuan,LIN Zhou,DING Chao
School of Earth Sciences, Zhejiang University, Hangzhou 310012, China
Abstract: The longitudinal profile of a bedrock channel in an equilibrium state appears as a smooth curve. However, the longitudinal profile of a river in nature often exhibits a transient state characterized by knickpoints, which are caused by the influence of earth's various internal and external dynamic effects. Therefore, the unbalanced channel profile and characteristics of knickpoints can indicate the disturbance of external environment. The drainage system of Minjiang River basin on the eastern margin orogenic belts of Tibetan Plateau is generally characterized by a transient state with widely developed knickpoints. In this study, we extract the spatial distribution of knickpoints based on a digital elevation model. After analyzing causes of the knickpoints, it was found that the formation of these
knickpoints are affected by lithology, glacial action, and tectonics. The knickpoints controlled by lithology were mainly located at the boundary between granite and other strata. High-altitude knickpoints located in the region with low terrain relief are mainly controlled by glacier. The slope-break knickpoints distributed in layers at low altitudes in the basin could be mainly formed by multiple episodes of regional tectonic uplift. In the longitudinal profile of lower part of Minjiang River, the stepped vertical-step knickpoints situated between steep slopes and gentle slopes were mainly caused by seismic landslides. The results help better understand regional geomorphic evolution and its influencing factors. Also, the results suggest that it is necessary to take into account glaciers and landslides in the analysis of the knickpoints in the river longitudinal profile as these factors have important impacts on longitudinal profiles of modern rivers. In addition, the results provide a new perspective for interpreting geomorphological evolution in an orogenic belt.
Keywords: longitudinal profile   knickpoint   Minjiang River   seismic landslides   eastern margin of Tibetan Plateau  
收稿日期 2019-04-30 修回日期 2019-06-05 网络版发布日期  
DOI: 10.16108/j.issn1006-7493.2019036
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