摘要
青藏高原夷平面形成年代是确定高原起始隆升时代和抬升幅度的重要证据.青藏高原东北缘祁连山地区4100～4300 m的海拔高度上保留有大片平坦地形面构成的夷平面,地质与地貌调查表明,夷平面切削古生代花岗岩类侵入体及晚古生代-古近纪地层,被夷平的最新地层为始新世-渐新世火烧沟组.祁连山抬升导致河流下切与断陷作用并形成深切河谷及断陷盆地,充填于古河谷及断陷盆地中的渐新世-中新世白杨河组开始沉积时代,代表了夷平作用过程的终止年代及导致夷平面解体的构造隆升时代.29个ESR测年数据表明,白杨河组沉积时代为34.4～11.89 Ma.由此推论,祁连山夷平面形成于始新世末（34 Ma之前）,形成时其高度在1000 m左右,34Ma左右祁连山夷平面开始解体并快速抬升.
Formation age of the planation surface within the Qinghai-Tibet Plateau is a key to understand the uplifting time and amplitude of the plateau.There are planation surfaces,in elevation of 4100～4300 m,covering large areas of the Qilian Mountains region on the northeast margin of the Tibetan Plateau.Geological and geomorphological survey results show that the Palaeozoic granitoid intrusion and the Late Paleozoic-Paleozoic strata have been truncated by the planation surface,with the Eogene Huoshaogou Formation being preserved as the underlain youngest strata.The uplifting of Qilian Mountains triggered the formation of some deep incised valleys and fault basins and in this context,the formation of the overlain sediments from Oligo-Miocene Baiyanghe Formation may represent an planation termination and initiation of tectonic uplift in Qilian Mountains area.Overall 29 electron spin resonance（ESR） dating data shows that the Baiyanghe Formation was formed during 34.4 Ma and 11.89 Ma.Hence,we speculate that the planation surface in Qilian Mountains was likely formed at the end of Eocene（i.e.,before 34Ma）,the contemporaneous altitude was about 1000m,and the plantation surface probably began to disintegrate and Qinlian Mountains uplifted rapidly around 34 Ma.
作者
贾丽云
王超群
沈燕绪
胡道功
赵希涛
戚帮申
张耀玲
陶涛
Jia Liyun;Wang Chaoqun;Shen Yanxu;Hu Daogong;Zhao Xitao;Qi Bangshen;Zhang Yaoling;Tao Tao(Institute of Geomechanics, Chinese Academy of Geological Sciences, Beifing 100081;Key Laboratory of Neotectonic and Geohazard, Ministry of Natural Resources, Beijing 100081;Cores and Samples Center of Land and Resources, China Geological Survey, Yanjiao 065201, Hebei;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029)
出处
《第四纪研究》
CAS
CSCD
北大核心
2018年第3期668-679,共12页
Quaternary Sciences
基金
国家自然科学基金项目（批准号：41702194）和中国地质调查局地质调查大项目（批准号：DD20160269和GZHL20120301）共同资助
