摘要
晚新生代以来,由于青藏高原的隆起,四川盆地周边及盆地内部,发育众多的褶皱变形及逆冲断裂。四川盆地西南缘的雅安-名山地区也发育系列褶皱变形如蒙顶山背斜。根据野外实地调查、DEM及卫星遥感影像的解译,古青衣江的一条古代主干河道在蒙顶山背斜被识别出来,该古河流控制了名邛台地的冲-洪积沉积。伴随古青衣江上游发生河流改道事件,名邛台地也停止发育,一段废弃河道在蒙顶山中被保留下来,并在蒙顶山背斜持续褶皱过程中,河流纵剖面遭受变形。根据名邛台地的ESR测年,可确定古青衣江被袭夺事件发生在312±3.0ka,结合河流纵剖面变形的几何计算,获得背斜开始发育的时间为3.2～3.8Ma,蒙顶山背斜相对于下里向斜的隆升速率为0.46mm/a。研究结果可以限定该地区褶皱构造活动的起始时间、变形速率以及山体的剥蚀速率。
The Ya＇an-Mingshan area lies in the southwest corner of the Sichuan Basin, where several linear folds including the Mingdingshan anticline occur. A paleo-channel of the Qingyijiang River was identified in DEM and satellite remote sensing images. It controlled the development of an alluvial-fluvial fan named the Ming-Qiong terrace. The upstream of the paleo-Qingyijiang River was captured,and so the Ming-Qiong terrace stopped building. However, one channel of the paleo-river was preserved, and it was then deformed during the rise of the Mingdingshan anticline. The ESR dating shows that the river capture or piracy event occurred in 312.0±3.0ka. It is estimated from deformation of that paleo-channel that the rise of the Mingdingshan anticline began in 3.2 - 3.8Ma. So the rise rate might be 0.46mm/a.
出处
《第四纪研究》
CAS
CSCD
北大核心
2010年第4期779-790,共12页
Quaternary Sciences
基金
地质灾害防治与地质环境保护国家重点实验室"科技减灾
重建家园"专项研究项目(批准号:DZJK-0804)
国家自然科学基金项目(批准号:40972084)资助
关键词
古青衣江
蒙顶山背斜
ESR测年
隆升速率
四川盆地
paleo-Qingyijiang River, Mengdingshan anticline, ESR dating, uplift rate,Sichuan Basin
