青藏高原层状地貌与高原隆升  

STEP-LIKE LANDFORMS AND UPLIFT OF THE QINGHAI-XIZANG PLATEAU

作　　者：潘保田[1] 高红山[1] 李炳元[2] 李吉均[1] 

机构地区：[1]兰州大学西部环境教育部重点实验室,地理科学系,兰州730000 [2]中国科学院地理科学与资源研究所,北京100101

出　　处：《第四纪研究》2004年第1期50-57,T005,共9页Quaternary Sciences

基　　金：国家自然科学基金项目 (批准号 :40 1710 10 );国家重点基础研究发展规划项目 (批准号 :G19980 40 80 0 );教育部"高等学校优秀青年教师教学科研奖励计划"资助

摘　　要：夷平面、剥蚀面和河流阶地等层状地貌面是长周期地貌演化研究的主要对象 ,它们不仅记录了区域地貌的发育历史 ,而且可以用来反演区域构造活动、气候变化等内动力过程的演变。深入研究青藏高原上这些地貌面的特征、变形、成因和形成时代 ,是探讨青藏高原隆升年代、幅度和过程的重要途径。野外考察与室内制图表明青藏高原及其边缘山地普遍存在两级夷平面 (山顶面、主夷平面 )、一级剥蚀面和多级河流阶地。主夷平面形成于 7.0～3.6MaB .P .,形成时其高度在 1 0 0 0m以下。大约 3.6MaB .P .前主夷平面开始大规模解体 ,标志着青藏高原强烈抬升的开始。剥蚀面和河流阶地揭示 ,1 .8MaB .P .,1 .2MaB .P .,0 .8MaB .P .和 0 .1 5MaB .P .Planation surface, erosion surface, fluvial terrace and other step like geomorphic surfaces in the Qinghai Xizang Plateau and its surrounding mountains were formed by long term planation and erosion, which recorded uplift history of the Qinghai Xizang Plateau. Therefore, studies on their features, formation, distortion and ages are very important to reconstructing ages and amplitudes of uplifting of the Qinghai Xizang Plateau. Field investigations and mapping of step like landforms have shown that there are two extensive planation surfaces (the Summit Surface and the Main Surface), a erosion surface and many fluvial terraces. The Summit Surface with a height of more than 5 500m above sea level being located in the core of mountains in the Qinghai Xizang Plateau, was formed in Oligocene and Early Miocene. The Main Surface is widespread and occupies the most part of the Qinghai Xizang Plateau, whose altitude decreases from 5 000m in the northwestern part of the Plateau to 3 500m in the eastern part. The Main Surface was formed during 7.0～3.6MaB.P. when its height was less than 1 000m a.s.l. The erosion surface, being distributed in the marginal mountains of the Qinghai Xizang Plateau, was formed in 1.8～1.4MaB.P. Under the erosion surface, Jintahe River in the eastern Qilianshan developed five terraces whose ages downwards are 1 24MaB.P., 0.78MaB.P., 0.14MaB.P., 0.06MaB.P. and 0.01MaB.P. , respectively. The Summit Surface was uplifted and destroyed in 25～23MaB.P. because of tectonic movement, and then the Main Surface was developed. Breaking up of the Main Surface at 3.6MaB.P. indicates the beginning of intense rising of the Qinghai Xizang Plateau. The erosion surface and many fluvial terraces recorded uplift processes of the Qinghai Xizang Plateau in last 3Ma. These intense uplift events, which happened 1.8MaB.P., 1.2 MaB.P., 0.8MaB.P. and 0.15MaB.P. , respectively, were important to formation of the Qinghai Xizang Plateau.

关 键 词：夷平面 剥蚀面 河流阶地青藏高原 隆升时代 幅度 

分 类 号：P931[天文地球—自然地理学] P542.2