青藏高原中部色林错区域古湖滨线地貌特征、空间分布及高原湖泊演化  

Geomorphic characteristics,spatial distribution of paleoshorelines around the Siling Co area,central Tibetan Plateau,and the lake evolution within the plateau

作　　者：孟恺[1,2] 石许华 王二七[1] 苏哲[1] 

机构地区：[1]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029 [2]中国科学院研究生院,北京100049 [3]Department of Geosciences,The Pennsylvania State University,University Park

出　　处：《地质科学》2012年第3期730-745,共16页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家重点基础研究发展计划"973"项目(编号:2011CB403106);国家自然科学基金项目(编号:41130312;40940018)资助

摘　　要：结合新近获得的高精度遥感影像和详细的野外调查,首次对青藏高原内部大型单个湖泊古湖滨线进行了系统的调查测量。综合色林错周边古湖滨线的地貌、沉积及地形特征,本文首次提出色林错周边区域古湖滨线从地貌上可以分为3类:1)处于高位,保存完好且非常连续的单级"高位古湖滨线";2)高于高位古湖滨线、严重退化、只有零散保存的多级"退化古湖滨线";3)低于高位古湖滨线、保存最好而非常连续的"低位古湖滨线"。野外系统测量表明,高位古湖滨线高程约4 593 m,最高退化古湖滨线高程为4 640 m。高位古湖滨线一致的高程分布表明:1)晚更新世高位古湖滨线形成时期存在一个更大的色林错古湖;2)自晚更新世以来,在色林错周边200 km范围内,不存在构造差异抬升。结合前人对西藏内部大型湖泊古湖滨线的年代学研究及本文的高程测量分析,指出关于晚更新世西藏中东部统一的古大湖——"古羌塘东湖"的提法值得商榷,晚更新世高原内部各大型湖泊更可能是通过河道串联。A systematic investigation has been conducted for the first time on paleoshorelines of a single large lake, Siling Co, within the Tibetan Plateau, through analysis of recently-released high-resolution remote sensing imagery and detailed field survey. According to the geomorphic, depositional and topographic characteristics of paleoshorelines around the Siling Co area, this study suggests, for the first time, that paleoshorelines around the Siling Co area can be categorized as three groups： 1 ） a single flight of highstand paleoshorelines which are characterized by their highstand position, nice preservation and continuation ; 2 ）several flights of highly-degraded paleoshorelines which posit above the highstand paleoshQrelines and are only sparsely preserved around the Siling Co and, 3 ） tens of flights of lowstand paleoshorelines that are blow the highstand paleoshorelines and show best preservation and continuation. Our systematic field survey demonstrates elevations of the highstand paleoshorelines are confined around 4 593 m, and that of the highest highly-degraded paleoshorelines is 4 640 m. The consistence in elevations of the highstand paleoshorelines implies that 1 ） a paleo-Siling Co with much larger lake extension existed during the time of formation of highstand paleoshorelines and, 2）no tectonic influence on the highstand paleoshorelines within 200 km around the Siling Co,since late Pleistocene. By synthesizing previous chronology of paleoshorelines preserved around large lakes within Tibet and the analysis of shoreline elevations from this study, we suggest that the proposal of a single great paleolake that unified all modern large lakes in the Middle and Eastern Tibet, the so-called ＂Great East Qiangtang Paleolake＂, is questionable ; it is more likely that those large paleolakes during Late Pleistocene were connected through river channels.

关 键 词：色林错 古湖滨线 古羌塘东湖 差分GPS 

分 类 号：P542[天文地球—构造地质学]