摘要
对可可西里西段新生代盆地缺乏了解是导致该区新生代地质演化存在争议的重要原因。本文以沉积学和构造变形分析为主要手段,对可可西里西段羊湖盆地时代、充填序列、物源区和变形特征进行了分析,结果表明,羊湖盆地新生界沉积厚度大于1302m,主要由下部雅西错组冲积扇相碎屑岩和上部五道梁群湖泊相碳酸盐岩组成,其岩石组合和充填序列与可可西里东段具有一致性,同时古流向和碎屑锆石U-Pb年代学分析显示盆地物源来南部的羌塘地块,盆地形成演化受南部褶皱冲断带制约,盆地构造变形强烈,沿褶皱冲断带和羊湖盆地地壳分别发生51%和41%的缩短。沉积充填结构和变形特征表明,羊湖盆地与东段可可西里盆地具有相同的演化历史和性质,预示青藏高原中部在渐新世-中新世在存在一个大的、统一的可可西里盆地。
The scale and structure attribute of the Hoh Xil basin are the keys to understand the Cenozoic evolution and uplift of the Tibetan Plateau. However, the sedimentation and deformation are poorly known about the western Hoh Xil that makes the present interpretations highly debatable. Here we report the results of sedimentary facies, detrital zircon U-Pb isotopic compositions and deformation of the Yanghu bain in the western Hoh Xil. There are two depositional sequences developed in the basin, including the lower alluvial fan and upper lacustrine facies, with a total thickness of exceeding 1302m. The lithofacies and facies association are similar with the Oligocene Yaxicuo Formation and Miocene Wudaoliang Group in the eastern Hoh Xil basin. Paleocurrent directions and detrital zircon indicate that the basin provenance was coming from the Qiangtang blocks, which is also in accordance with eastern Hoh Xil basin. Moreover, two tectonic units are identified in this area, they are the southern thrust belt and Yanghu bain from south to north, which have caused 51% and 41% crustal shortening during Early Tertiary respectively. These observations, in combination with sequential filling patterns, sedimentary facies and deformation all indicate that the Yanghu basin has undergone similar evolution with the eastern Hoh Xil basin, imply that there was a single, wide basin in the Central Tibetan Plateau during Paleogene-Miocene.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第3期1017-1026,共10页
Acta Petrologica Sinica
基金
国家自然科学基金项目(41172129)
国家重点基础研究发展规划项目(2011CB822001)
中国地质调查局项目(1212011221103)联合资助
