Late Triassic Sedimentary Geochemistry and Tectonic Significance in the Yajiang Basin, Sichuan
详细信息
- 责任者：Wang Hui (Shaanxi Center of Geological Survey ; Xi′an 710065 ; China) ; Ruan Linsen
- 刊名：Northwestern Geology
- 出版年：2012
- 卷期：45(2)
- 关键词：砂岩 ; sandstone ; 沉积地球化学 ; sedimentary geochemistry ; 大地构造 ; tectonics ; 四川 ; Sichuan Province
- 页码：p.88-98
- 图表：illus., 5 tables, 28 refs.
- 分类号：0803
- issnNo：ISSN1009-6248
- isbnNo：CN61-1149/P
摘要
Eighteen clastic sedimentary rock samples from the Triassic typical section in the Yajiang Basin are analyzed.The SiO 2 content changes mainly from 70%to 90%and the Al2O3content 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 / SiO 2 , K 2 O / N 2 O , and Fe 2 O 3 + 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.