西藏阿里札达盆地上新世—早更新世河湖相沉积中两个不整合面的发现及意义  

Discovery of two unconformities in Pliocene-early Pleistocene fluvio-lacustrine deposits in the Zanda basin, Ngari, Tibet

作　　者：朱大岗[1] 孟宪刚[1] 邵兆刚[1] 杨朝斌[2] 孙立倩[1] 王建平[1] 韩同林[3] 韩建恩[1] 杜建军[1] 余佳[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]西藏自治区国土资源厅,西藏拉萨850000 [3]中国地质科学院地质研究所,北京100037

出　　处：《地质通报》2004年第5期605-608,共4页Geological Bulletin of China

基　　金：中国地质调查局<青藏高原第三纪重点古湖泊环境演变序列>项目(编码:200313000066)的阶段性研究成果。

摘　　要：通过札达盆地河湖相地层的野外实测剖面和地质调查,结合前人资料,根据沉积岩性、不整合面、所含化石、固结程度和岩相变化,初步将这套水平产出、原顶底及接触关系不明的新近纪上新世—第四纪早更新世河湖相地层,划分为1个群、3个组、2次构造运动(不整合)。从新到老为下更新统香孜组(Qp1x)和上新统古格群(N2gg),其中后者又细分为上新统札达组(N22z)和上新统托林组(N12t)。河湖相沉积中香孜组与札达组、札达组与托林组之间2个不整合面的发现和象泉运动与古格运动2次构造运动的确定,为研究青藏高原隆升过程、该区新近纪以来湖泊与河流演化、气候变化、古地理变迁和环境演化,以及新近系、第四系地层划分等提供了新资料。A sequence of horizontal Pliocene-Quaternary fluvio-lacustrine deposits occurs in the Zanda basin, Tibet, but its top and bottom and its contact relationships with the overlying and underlying strata are not defined. By field geological survey and measured sections, the lithologies, unconformities, contained fossils, consolidation degree and lithofacies change of the sedimentary rocks have been made clear. On that basis, combined with previous data, this sequence of fluvio-lacustrine deposits are divided into one group and three formations, and in addition two tectonic movements (unconformities) have been recognized. They are from younger to older the early Pleistocene Qangzê Formation (Qp1x) and Pliocene Guge Group (N2gg), of which the latter may be subdivided into the Pliocene Zanda Formation (N22z) and the Pliocene Toling Formation (N12t). The discovery of the unconformities between the Qangzê Formation and Zanda Formation and between the Zanda Formation and Toling Formation and the definition of the Xiangquan movement and Guge movement provide new data for the study of the uplift process of the Qinghai-Tibet Plateau and the evolution of lakes and rivers, climatic changes, paleogeographic changes and environmental evolution, as well as the stratigraphic division of the Neogene and Quaternary in the study area.

关 键 词：西藏札达 上新世-早更新世 河湖相沉积 不整合面 

分 类 号：P534.622[天文地球—古生物学与地层学] P534.631[天文地球—地质学]