西藏改则盆地渐新统—中新统康托组沉积相特征

摘要

The Gerze basin located in the Qiangtang stratigraphic area of the Tibetan Plateau has been very insufficiently studied. According to the sedimentary characteristics of the Oligocene-Neogene Kangtuo Formation, three sedimentary facies have been recognized in the Gerze basin, i.e., fan delta facies, lacustrine delta facies and lacustrine facies. In combination with regional geological characteristics and paleocurrent analysis, the Oligocene-Neogene sedimentary evolution in the study area is divided into two stages, which in the chronological order are the initial rift-sagging stage and the steady depositional stage. The facies analysis of the Kangtuo section has obviously shed light on the understanding of the Oligocene-Neogene sedimentary evolution in the study area.%改则盆地地处青藏高原羌塘地层区,研究程度较低.通过对西藏改则盆地新近系康托组沉积特征和沉积岩相的详细研究,共划分出3类沉积相:扇三角洲相、湖泊三角洲相和湖泊相,整体表现为自下向上沉积物粒度由粗到细、水深逐渐增大的退积序列.综合区域地质特征及古流向分析认为,改则盆地渐新世—中新世的沉积演化可大致分为2个阶段:盆地初始裂陷阶段和盆地稳定沉积阶段.康托组剖面沉积相的研究有助于了解改则盆地渐新世—中新世的沉积演化.