可可西里东部地区的夷平面与火山年代  

A PLANATION SURFACE AND AGES OF VOLCANIC ROCKS IN EASTERN HOH XIL, QINGHAI-TIBETAN PLATEAU

作　　者：李炳元[1] 潘保田[2] 高红山[2] 

机构地区：[1]中国科学院地理科学与资源研究所,北京100101 [2]兰州大学地理科学系,兰州730000

出　　处：《第四纪研究》2002年第5期397-405,共9页Quaternary Sciences

基　　金：国家重点基础研究发展规划项目 (批准号 :G1 9980 4 0 80 0 );高等学校优秀青年教师教学科研奖励计划共同资助

摘　　要：青藏高原夷平面及其年代是高原隆升、时代和幅度研究中的一个关键问题。可可西里东部地区通过 1∶1 0 0 0 0 0航测地形图所示的山顶面形态特征分析表明 ,本区广泛分布的山顶平坦地形面为青藏高原主夷平面的一部分 ,其海拔高度大多在 490 0～ 5 2 0 0m。本区平坦顶面的熔岩方山常与夷平面交叉分布 ,也为高原主夷平面一部分 ,其同位素年代 1 9.6～6 .95MaB .P .之间的有 3 9个 (9.9～ 6 .95MaB .P .有 1 7个 )。又据本区相邻的山间盆地内的火山地貌年龄推论 ,夷平面形成于 9.9～ 6 .95MaB .P .之后 ,3MaB .P .The planation surface of the Qinghai-Tibetan Plateau can be regarded as its original position before uplift, so the research of its feature, altitude, deformation and age is a key to recognize the amplitude and age of uplift of the plateau. A widespread and flat summit surface with elevations of 4?900～5?200m can be recognized on 1∶100?000 aerial topographic maps of eastern Hoh Xil. This surface can be considered a part of the planation surface of the Qinghai-Tibetan Plateau. On the other hand, Cenozoic lava platforms or mesas are also widespread in the eastern part of Hoh Xil. In many places their flat tops are intersected by the planation surface of the Qinghai-Tibetan Plateau. This relation shows that the age of the volcanic lava can proximately represent the age of the planation surface of the Qinghai-Tibetan Plateau. Now, there are 45 isotopic age values of the lava. Among them, 39 are between 19.6Ma B.P. and 6.95Ma B.P., and 17 between 9.9Ma B.P. and 6.95Ma B.P. Considering the intersecting relation between the lava top and the planation surface, combined with ages of volcanic rocks in adjacent intermountain basins, it can be deduced that the the planation surface in eastern Hoh Xil would form after 6.9 Ma B.P. and before 3Ma B.P.$$$$

关 键 词：可可西里东部地区 火山地貌 夷平面 形成年代 高原隆升 

分 类 号：P317[天文地球—固体地球物理学]