青藏高原东北缘共和-茶卡盆地晚新生代构造变形与地貌演化  

Late Cenozoic tectonic deformation and geomorphological evolution in the Gonghe-Chaka Basin on the northeastern margin of the Tibetan Plateau

作　　者：张会平[1] 刘彩彩[1] 熊建国 庞建章[1] 俞晶星[1] 王一舟[1] ZHANG Huiping;LIU Caicai;XIONG Jianguo;PANG Jianzhang;YU Jingxing;WANG Yizhou(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029)

机构地区：[1]中国地震局地质研究所地震动力学国家重点实验室,北京100029

出　　处：《第四纪研究》2022年第3期662-672,共11页Quaternary Sciences

基　　金：科技部第二次青藏高原综合科学考察研究项目(批准号:2019QZKK0704);国家自然科学基金项目(批准号:41622204和41888101)共同资助。

摘　　要：青藏高原东北缘作为现今高原向北东方向最新扩展生长的前缘部分,包括了南部高海拔、低起伏的东昆仑高原以及北部盆山相间的祁连山高原及其邻近地区。有关该区晚新生代构造变形及地貌演化研究,有助于揭示青藏高原生长过程的动力学机制。文章选择青藏高原东北缘共和羊曲、茶卡大水桥等新近纪沉积剖面,通过总结磁性地层学、沉积学资料,综合厘定了共和-茶卡盆地及邻区约20 Ma以来的盆地消亡及地貌演化过程;在现有盆地沉积、构造热年代学以及夷平面变形等研究结果基础上,获得青海南山和共和南山及其前陆的构造缩短量分别为0.8~2.2 km和5.1~6.9 km;并以约6~10 Ma和约7~10 Ma的生成地层记录的变形时间为约束,得到晚中新世以来的缩短速率分为0.1~0.2 mm/a和0.8~1.0 mm/a,这与断裂陡坎揭示的断裂逆冲速率及现今GPS观测相符合,表明10 Ma以来构造变形速率的相对稳定性和连续性;共和-茶卡盆地及祁连山南缘广泛发育低起伏地貌面,后期被不断抬升至现今高度塑造高原地貌形态。上述认识为理解晚新生代以来青藏高原东北缘的形成过程提供了基础资料。The northeastern margin of the Tibetan Plateau,as one of the frontiers of the latest expansion and growth of the present plateau in the northeast direction,includes the transitional areas from the high-altitude,undulating East Kunlun Plateau in the south to the Qilian Mountains in the north with alternating basins and mountains.The Late Cenozoic tectonic deformation and geomorphological research will help to reveal the dynamic mechanism of the growth and evolution of the Qinghai-Tibet Plateau.On the basis of the existing results of magnetostratigraphy,sedimentology and low temperature thermochronology in the northeastern margin of the Tibetan Plateau,this paper focuses on the Neogene sedimentary characteristics of Gonghe Yangqu and Chaka Dashuiqiao,and gives the Gonghe-Chaka Basin and its characteristics.The history of tectonic deformation and geomorphic evolution in the adjacent area since ca.20 Ma.The main body of the Gonghe Yangqu section is composed of three sets of Cenozoic lithostratigraphic units,the oldest set of L1 stratigraphic units(about 20.0~8.7 Ma)is composed of brick red plate mudstone intercalated with sandstone and siltstone lens,which is fluvial facies-shallow lacustrine facies environment;The L2 stratigraphic unit(8.7~6.8 Ma)in the profile is interbedded with orange and tan thin-layered siltstone,gray conglomerate and multicolored mudstone.Compared with L1,the abundance of fluvial sediments in L2 increases significantly;the rock in profile L3 The stratigraphic unit(6.8~0.5 Ma)is thick conglomerate,which is a braided channel alluvial fan deposit.The stratigraphic sequence developed in Gonghe Yangqu section shows a reverse grain sequence that becomes coarser upwards.The main sedimentary environment bodies such as braided rivers and alluvial-proluvial fans represented by coarse grains such as conglomerate start from the L2 stratum,implying that the basin The topographic height difference on the periphery began to increase rapidly,indicating that the surrounding mountains began to uplift.The bottom

关 键 词：青藏高原东北缘 共和-茶卡盆地 新生代 构造变形 地貌演化 

分 类 号：P546[天文地球—构造地质学]