Geochemical Features of Siliceous Sediments of the Shuicheng-Ziyun-Nandan Rift Basin in the Late Paleozoic and Their Tectonic Implication
详细信息
- 责任者：Huang Hu (State Key Laboratory of Biogeology and Environmental Geology ; China University of Geosciences ; Wuhan 430074 ; China) ; Du Yuansheng
- 刊名：Acta Geologica Sinica
- 出版年：2012
- 卷期：86(12)
- 关键词：硅质岩 ; silicolite ; 广西 ; Guangxi Province
- 页码：p.1994-2010
- 图表：3 illus., 3 tables, 66 refs.
- 分类号：0803
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
///The Shuicheng-Ziyun-Nandan rift basin (SZNRB) is located in the northern margin of the Youjiang Basin. Geochemical analysis for siliceous sediments indicates that siliceous deposits from the bottom of the Upper Devonian Liujiang Formation in the Nandan area and the Lower-Middle Permian Sidazhai Formation in the Hechi area were genetically associated with basaltic volcanic eruption and hydrothermal activity, and showed lower Al/(Al+Fe+Mn) and Al2O3/TiO2 values.The siliceous sediments of the Lower-Middle Permian Sidazhai Formation in the Ziyun area have a Al/(Al+Fe+Mn) value of 0.62±0.16 and Al2O3/TiO2 value of 11.70±4.30, suggesting a pyroclast-bearing nonhydrothemal origin, while the other siliceous sediments were precipitated in normal marineenvironments. With rifting and expanding of the basin and, siliceous sediments was interbedded with dark thick limestone to the Early-Middle Permian. The siliceous sediments are characterized by large negative Ce-anomalies(0.06～0.61) and a similar Y/Ho values(40～92) as that in open-ocean seawater, and a high ∑REE+Y value twice higher than PAAS-like composition after deducing the effect of SiO2 dilution.