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甘肃疏勒河冲积扇是面积达 2 4 0 0km2 的一个巨型冲积扇 ,位于青藏高原北缘阿尔金断裂带东端。区域构造上该扇发育在阿尔金主断裂、三危山断裂和南截山断裂组成的阿尔金断裂带左旋走滑构造域。根据野外调查获得的沉积层序、地貌形态和构造变形等资料 ,该冲积扇可划分为老冲积扇和新冲积扇。老冲积扇扇顶紧靠阿尔金主断裂 ,由已显著构造变形的早更新统玉门砾岩组成 ;新冲积扇是在老冲积扇基础上发育的 ,扇顶已向下游移动到大坝附近 ,距阿尔金主断裂 4km ,主要由中更新统酒泉砾石和晚更新统戈壁砾石组成。疏勒河冲积扇发育对区域构造活动的响应主要表现为 :1 )在第四纪早期 ,阿尔金断裂的左旋走滑兼逆冲运动 ,导致了由玉门砾岩组成的疏勒河老冲积扇扇头被左旋错动约 8km ,同时扇体 ,尤其扇头明显褶皱隆升 ,扇顶向山外移动 ;2 )此后随着阿尔金断裂继续作左旋走滑兼逆冲运动 ,老冲积扇扇头又被左旋错动了约 2km ,总共左旋位移了约 1 0km ,并且扇顶下移了约 4km ,形成新的冲积扇 ;3)在冲积扇内从早更新世至晚更新世沉积中心不断向下游移动 ,呈现向下游超覆沉积的特征 ,这也一定程度上反映了祁连山隆升、向外扩展和侵蚀作用显著
The Shulehe alluvial fan in Gansu Province is a giant alluvial fan covering an area of 240 km 2 and located at the eastern end of the Altyn Tagh fault in the northern margin of the Qinghai-Tibet Plateau. On the regional structure, the fan develops in the left-lateral strike-slip tectonics domain of the Altyn Tagh fault consisting of the main Altyn Tagh fault, the San-zhunshan fault and the Nanjieshan fault. The alluvial fan can be divided into the old alluvial fan and the new alluvial fan according to the sequence of sedimentary sequence, topography and tectonic deformation obtained from field surveys. The alluvial fan fan top abutted the main Altyn Tagh fault and consisted of early tectonic Yumen conglomerates that had been significantly deformed. Neo-alluvial fans developed on the basis of the old alluvial fan and the fan roof had moved downstream to near the dam , 4km away from the main Altyn Tagh fault, mainly composed of the Middle Pleistocene Jiuquan gravel and late Pleistocene Gobi gravel. The response of the Shule alluvial fan to the regional tectonic activities is mainly as follows: 1) In the early Quaternary, the left-lateral strike-slip and thrusting of the Altyn Tagh fault resulted in the Shule alluvial alluvial At the same time, the fan body, especially the fan head, is obviously folded and uplifted and the fan head moves to the outside of the mountain. 2) Since then, the alluvial fan fan continues to make left-lateral strike-slip and thrusting movements along with the Altun fault The head was again displaced by about 2 km in the left-hand direction, displacing a total of about 10 km in the left-hand direction and the fan top moved downward by about 4 km to form a new alluvial fan. 3) The depositional center from Early Pleistocene to late Pleistocene in the alluvial fan Migrating downstream and showing the characteristics of overlying sediments to the lower reaches, which also partly reflects the significant uplift, outward expansion and erosion of the Qilian Mountains