黄河中上游阶地对青藏高原东北部第四纪构造活动的反映  

QUATERNARY TECTONIC ACTIVITY IN NORTHEASTERN QINGHAI-XIZANG PLATEAU AS REFLECTED BY RIVER TERRACES ALONG THE MIDDLE-UPPER REACH OF THE YELLOW RIVER

作　　者：刘百篪[1] 刘小凤[1] 袁道阳[1] 郑文俊[1] 郭华[1] 曹娟娟[2] 

机构地区：[1]中国地震局兰州地震研究所,兰州730000 [2]云南省地震局,昆明650041

出　　处：《地震地质》2003年第1期133-145,共13页Seismology and Geology

基　　金：国家重点基础研究发展规划项目 (G19980 4 0 70 10 4 )资助。

摘　　要：黄河中上游河段是横贯整个“柴达木 -祁连山活动地块”的贯流水系。通过对青海共和至宁夏石嘴山段长约 180 0km的黄河中上游阶地的系统考察、阶地剖面实测和年代测定 ,绘制了该河段的阶地纵剖面图。综合分析各段的阶地级数、高度、年代及变形特征得到以下认识 :该流域可划分为若干个次级活动地块 ,表现在不同地块之间的阶地抬升幅度和速率存在较大差别 ;活动地块内部在较大程度上具刚性特征 ,表现在块体内部阶地级数、高度和形成年代基本相当 ;阶地纵剖面反映的本区活动地块自 1.6MaB .P .以来的抬升量大于 3.6～ 1.6MaB .P .的抬升量 ;柴达木 -祁连山活动地块距今 1万年以来和 15～ 2 0万年间存在 2次强烈的构造抬升运动。The middle-upper reach of the Yellow River is a flowing water system passing through the whole 'Qaidam-Qilianshan active block'. We systematically investigated the river terraces of the Yellow River of about 1 800km length from Gonghe of Qinghai to Shizuishan of Ningxia, measured about 73 cross sections of terraces and obtained 88 age data in total. In addition, we have compiled the vertical profiles of river terraces on this river segment, and carried out the comprehensive analyses of the number, heights, ages and deformation features of the terraces. The following conclusion can be drawn from the obtained results: 1.These drainage areas can be divided into several secondary active blocks; they are Gonghe, Lanzhou, Haiyuan, Weining basin (Alashan) and Yinchuan basin (Ordos) secondary blocks, each of which is bounded by regional active faults and is independent of the others. The amplitudes and rates of uplift of the terraces in each block are significantly different, while those in the southern block are larger than those in the northern. For example, the relative elevation above river level of terrace planes of 1.60Ma age from south to north are: 400m in Gonghe block, 105～200m in Lanzhou block, 200～265m in Haiyuan block, 135～147m in Weining basin block, and -842m in Yinchuan basin block, respectively. 2. The interiors of the secondary active blocks are to some extent rigid, so the number, altitudes and ages of the terraces within the blocks are about the same, while the vertical profiles are relatively continuous and smooth. However, folding deformation is also obvious in local zones due to thrusting and other reasons. 3. Vertical profiles of river terraces reflect that the uplift amplitude of the Qaidam-Qilianshan active block since 1.6Ma B.P. is greater than that during 3.6～1.6Ma B.P. 4. Vertical profiles of terraces from Gonghe to Shizuishan segment of the Yellow River indicate that the rate of crustal uplift during 0.15～0.20 Ma B.P. is 2～6 times as high as that in the other periods, and the

关 键 词：黄河 河流阶地纵剖面 活动地块 构造隆升 主夷平面 

分 类 号：P315.2[天文地球—地震学]