摘要
前人对北川湔江袭夺湾位置的争议引发了对古湔江流向演化模式的争议。通过对断裂构造的水系响应方式的研究并辅以河流地貌证据,表明湔江的流向演化经历了银屏口分水岭迁移的主动袭夺过程和新构造运动造成湔江改道的被动袭夺过程,都坝河与通口河近似直角的交汇端应为袭夺湾的准确位置。具体来说,沿断裂发育的古都坝河在曲山镇附近首先注入古湔江,通口河溯源侵蚀切穿银屏口分水岭,古都坝河上游河段被通口河袭夺后改道注入通口河,古都坝河下游河段成为断头河。随后,因构造隆升而南流受阻的古湔江在曲山镇附近改道,水流沿已成断头河的古都坝河下段河道注入通口河。计算表明,北川湔江由古流向向现代流向转变的时期大致为距今 970ka的早更新世晚期。
Previous controversies regarding the accurate position of Jian river s elbow of capture in Beichuan county lead to the controversies on its evolution model of flow direction.According to the study of response modes of water systems to faulted structures and the evidence of fluvial geomorphology,it indicated that there were two processes involved in the flow direction evolution of Jian river including the migration of Yinpinkou water divide (active river capture) and the transformation of flow direction caused by new tectonic movement (passive river capture).The right angled intersection of Duba river and Tongkou river was the accurate position of Jian river s elbow of capture. To be specific,paleo-Duba river which was developed along the fault flowed into the paleo-Jian river near Qushan town,the Yinpingkou watershed was cut by the headward erosion of Tongkou river,and the lower reach of paleo-Duba river became beheaded because its upper reach was diverted into Tongkou river.Subsequently,the paleo-Jian river diverted near Qushan town because of tectonic upliftand then flowed into Tongkou river along the beheaded lower reach of paleo-Duba river.Calculations in this paper showed that the transformation period of flow direction of Jian river was the late of early pleistocene (970 ka BP).
作者
陈浩
李勇
CHEN Hao;LI Yong(College of Resources and Environmental Engineering,Mianyang Normal University,Mianyang 621006,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China)
出处
《山地学报》
CSCD
北大核心
2019年第2期206-213,共8页
Mountain Research
基金
国家自然科学基金资助项目(41172162)
四川省教育厅自然科学基金资助项目(14ZB0265)~~
关键词
湔江
流向演化
断裂构造
北川
Jian river
transformation of flow direction
fault structure
Beichuan county
