研究区处于青藏高原东南部,研究其高原隆升和盆地的形成背景与演化对探明整个青藏高原的演化和资源环境效应具有十分重要的意义.系统分析了雅江盆地三叠纪典型剖面的细粒碎屑沉积岩的主量和微量元素化学成分,在沉积地球化学研究的基础上,结合古生物研究成果,得出三叠纪晚期雅江盆地的构造环境为由被动大陆边缘发展而来的大陆岛弧或者活动大陆边缘,在地球化学特征上显示具有大陆地壳特点的小洋盆.%Eighteen clastic sedimentary rock samples from the Triassic typical section in the Yajiang Basin are analyzed The SiO2 content changes mainly from 70% to 90% and the A12O3 content is mainly from 8% to 10%, which indicates weak carbonization. The REE analysis shows that the Triassic sandstone from the Yajiang Basin is characterized by typical supracrustal enclaves. The LaN/YbN ratio indicates that the Yajiang Basin group and Zagunao group are the border of the continental island arcs and passive continent. The Eu/Eu * ratio from the Yajiang group and Xinduqiao group is greater than that of the other two groups, which indicates their sources are different. Ce exception indicates that the redox conditions in the sedimentary environments change greatly. The analysis of Al2O3/SiO2, K2O/N2O, and Fe2O3+MgO shows that the sources of the Yajiang Basin are mainly acid rocks. La-Th and Zr-Th discrimination diagrams and functions are used. The comprehensive analysis of the study leads to the conclusion that the geochemical characteristics of the Yajiang group, Lianghekou group, Xinduqiao group, and Zagunao group in the Yajiang Basin in the late Triassic period reflect the respective tectonic backgrounds: active continental margin, continental island arc, and passive continental margin.
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