地质学报2012，Vol.86Issue(12)：1994-2010,17.
水城-紫云-南丹裂陷盆地晚古生代硅质沉积物地球化学特征及其地质意义
Geochemical Features of Siliceous Sediments of the Shuicheng-Ziyun-Nandan Rift Basin in the Late Paleozoic and Their Tectonic Implication
摘要
Abstract
The Shuicheng-Ziyun-Nandan rift basin (SZNRB) is located in the northern margin of the YoujiangBasin. During late Paleozoic, the basin was dominated by carbonate platform-basin faices deposition including siliceous rock. Sedimentary assemblage and geochemical features of the siliceous rock are different from that of siliceous rocks in the continental shelf and accretionary complexes. 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/CAl+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. During the Late Devonian-Early Carboniferous, siliceous sediments were intercalated with mudstone and limestone, and show moderately negative Ce-anomalies (0. 6～0. 85mostly) and higher Y/Ho values (30～45 mostly), and low 2REE + Y values three times lower than PAAS-like composition after deducing the effect of SiO2 dilution. With rifting and expanding of the basin and, siliceous sediments was interbedded with dark thick limestoneto 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 2REE+Y value twice higher than PAAS-like composition after deducing the effect of SiO2 dilution.关键词
晚古生代/硅质沉积物/台盆相/地球化学/沉积环境Key words
late Paleozoic/ siliceous sediments/ interplatform basin/ geochemistry/ depositional environment引用本文复制引用
黄虎,杜远生,杨江海,陶平,黄宏伟,黄志强,谢春霞,胡丽沙..水城-紫云-南丹裂陷盆地晚古生代硅质沉积物地球化学特征及其地质意义[J].地质学报,2012,86(12):1994-2010,17.基金项目
本文为国家自然科学基金项目(编号40972078、40921062)、"111"项目(编号B08030)和贵州省地矿局2009年度重大科研项目《水城-紫云-南丹晚古生代裂陷作用及其与主要矿产的关系》共同资助的成果. （编号40972078、40921062）
