摘要
青藏高原东北缘黄河黑山峡出口地段夜明山 -长流水沟一带 ,黄河的河流阶地发育和保存的较好。阶地的形成不仅记录了青藏高原北部第四纪以来地壳的 7次隆升过程的特点 ,而且阶地的空间展布及其特征反映了断层F8(7) 和F2 0 1活动的特点。详细的观测研究表明F8(7) 以南发育并保存有 7级阶地 ,而F8(7) 和F2 0 1之间及F2 0 1以北仅保存有 5级阶地。所有的阶地都为基座阶地。其中Ⅰ和Ⅱ级阶地前缘在区内连续展布 ,横跨断层F8(7) 两侧的Ⅲ级阶地前缘仍保持连续 ,但阶地宽度陡然变宽 ,Ⅳ级阶地前缘即Ⅲ级阶地后缘左旋位移 15 0m左右。横跨断层F2 0 1两侧 ,Ⅱ级阶地宽度由 2 0 0m急剧变宽为 710m ,Ⅱ级以上阶地前缘左旋位移均在 4 0 0m左右。断层F8(7) 和F2 0 1两侧阶地宽度的变化和阶地前缘的左旋位移记录了断层F8(7) 和F2 0 1第四纪晚期活动的时空规律 。
River terraces were developed and preserved well in the outlet of Heishan Gorge of the Yellow River, Northeast margin of the Tibetan Plateau. The terraces not only documented the uplift history of northeast part of the Tibetan Plateau since Quaternary, but its characteristics and distribution also reflect the active features of F 8(7)and F 201 faults. Detailed studies show that there are seven terraces preserved to the south of F 8(7) fault but only five terraces preserved to the north of F 8(7) fault and to the north of F 201 fault. All the terraces are pedestal terrace. The frontier lines of the TerraceⅠ,Ⅱ and Ⅲ is continuous, but the width of Terrace Ⅲ increase sharply across the F 8(7) and sinistral displacement of the frontier line of Terrace Ⅳ and,Ⅴ amounts to 150 meter. The width of TerraceⅡ changes from 200 meter to 710 meter across F 201, and the frontier line of the terrace Ⅲ, Ⅳ andⅤ displaced to 400 meter across F 201. Those changes of width and displacement of the terraces documented F 201 and F 8(7) fault activity since Pleistocene, which provide us with important data for evaluation of fault activity.
出处
《工程地质学报》
CSCD
2004年第4期367-372,共6页
Journal of Engineering Geology
