论晚期共和古湖时代、演化过程及其与地壳运动和黄河发育的关系  

A Discussion on the Age and Evolution Process of the Late Gonghe Paleolake and Its Relations with the Crustal Movement and the Development of the Yellow River

作　　者：赵希涛[1] 杨艳[2] 贾丽云[3] 胡道功[3] 李维东 张耀玲[3] 林旭 ZHAO Xi-tao;YANG Yan;JIA Li-yun;HU Dao-gong;LI Wei-dong;ZHANG Yao-ling;LIN Xu(Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;Chinese Academy of Geological Sciences,Beijing 100037;Key Laboratory of Neotectonic Movement and Geohazard,Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081;Research Center for Strategy of Global Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037;College of Civil Engineering and Architecture,China Three Gorges University,Yichang,Hubei 443002)

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国地质科学院,北京100037 [3]新构造运动与地质灾害重点实验室,中国地质科学院地质力学研究所,北京100081 [4]中国地质科学院全球矿产资源战略研究中心,北京100037 [5]三峡大学土木与建筑学院,湖北宜昌443002

出　　处：《地球学报》2021年第4期451-471,共21页Acta Geoscientica Sinica

摘　　要：青海共和盆地,是青藏高原东北部晚新生代期间形成的北西西—南东东走向构造盆地,由西北部的茶卡小内流盆地,中部非典型的达连海内流盆地和东南部被黄河及其支流深深切割的外流盆地三部分组成。该盆地中充填了上、下两套厚度普遍均在200~300 m间,而最厚部分可达500~600 m的相互叠置的共和组与曲沟组河湖相地层。由这两套湖相地层所重建的古湖被分别称为早期和晚期共和古湖。本文重点讨论的是基于共和组湖相地层而重建的晚期共和古湖。石英热活化法ESR测年结果表明,湖相共和组地层开始形成于(4.31±0.40)Ma之前,持续到(2.58±0.20)Ma/(2.54±0.20)Ma之后的上新世时期。以尕玛羊曲村附近为顶点的黄河扇三角洲相两套均厚逾200 m砾石层中之上砾石层,形成于(3.15±0.30)—(3.07±0.30)Ma之间,其前缘水下三角洲相砾石层为(2.91±0.25)Ma,而来自北部山前的同期洪积砾石层则为(2.97±0.27)Ma,表明晚期共和古湖在(3.07±0.30)Ma与(2.91±0.15)Ma之间的上新世晚期达到其最盛期。此时,湖面高度达到其最大值海拔(3160±10)m左右,古湖是一个面积近7000 km2、深逾300 m的大型外流的淡水深湖。黄河在尕玛羊曲附近注入古湖,并由盆地东北角的尕海以东流出,经唯一通道古多隆河流入贵德古湖。当古湖面上升到超过共和与贵德两盆地的基岩分水岭时,黄河在现今的龙羊峡位置切割出新的河道——龙羊峡,从而导致了早更新世初古多隆河因“截弯取直”而非“溯源侵蚀”被废弃,开始了黄河逐步下切、T21到T16形成与共和古湖逐渐消亡的过程。共和古湖经历了茶卡盆地开始与古湖主体分离,中部湖区与东南部湖区分离、排干和东南部湖区被完全泄空等3个阶段。这一过程是随着中国区域地壳运动性质发生的根本性变化而发生的。此时,共和盆地及邻近盆地,甚至中国第一、二大地势阶梯上的大�Gonghe Basin,as one of the numerous basins in northeastern Tibetan Plateau,is a kind of medium-scale tectonic basin,consisting of three parts:endorheic basin—the Chaka Salt Lake in the northwest,nontypical endorheic basin represented by small salt water lake such as the Dalian Lake in the middle,and external basin incised by the Yellow River and its tributaries in the southeast.There are two series of contraposed stratigraphic units:Gonghe Formation in the upper part and Qugou Formation in the lower part,which are filled in the Gonghe Basin.The thicknesses of these two sets of strata are mainly between 200 and 300 m,with the thickest reaching 500~600 m.The facies types are mainly coarse clastic deposits from the foothills around the basin and lacustrine fine-grained deposits in the center.The latter strata have redder color,stronger diagenesis,and wider distribution ranges,and experienced more tectonic activities.The paleolake,reconstructed by these two strata,is named Gonghe Paleolake.The early Gonghe Paleolake was reconstructed by the Qugou Formation,and the late one,the Gonghe Formation.The late Gonghe Paleolake,which is the focus of this paper,experienced the vegetation change process of stappe,forest-steppe,stappe,forest-steppe,stappe,forest-steppe and present steppe,indicating that the change from warm temperate zone to temperate zone,experiencing several times of climatic changes of cold-warm and dry-humid,and the general trend being aridification.During the maximum stage,the paleolake reached its maximum height,being(3160±10)m a.s.l..The Gonghe Paleolake was a deep freshwater lake,with the area of nearly 7000 km2 and the depth of more than 300 m,where the Yellow River flowed in from the Gamayangqu Village,Xinghai Countay,and flowed out from east of the Gahai,through the ancient Duolong River,and hence the Yellow River was a river flowing through Duolonggou and Qunaihai Village to Guide Paleolake.During the period of the strongest development of paleolake,the Yellow River flowed into the Gonghe Basin an

关 键 词：共和盆地 共和古湖 ESR测年 上新世 古湖演化 黄河发育 恰不恰(共和)运动 

分 类 号：P931.7[天文地球—自然地理学] P597.3