西北地质Issue(2)：31-42,12.
上扬子地块北缘灯影组硅质岩系地球化学特征及其成因
Geochemical Characteristics and Genesis of Cherts of Dengying Formation on the North Rim of Yangzi Block
摘要
Abstract
Field survey indicates that a large scale of cherts occur in Dengying formation of Sinian Systemin the tectonic belt of Dabashan and Micangshan,together with carbonatite.The results of trace and rare earth elements analysis indicate that the cherts have the characteristics of hydro-thermal origin.Among the trace elements,Ba is enriched and most of the Ba/Sr ratio is greater than 1.Th/U ratio is less than 1 and the values from all samples fall into the hydrothermal sedi-ment area in the Th-U diagram.Zr is also enriched and its content in all samples are neighboring the hydrothermal sediment trend line in the Zr-Cr diagram.The ∑REE of cherts is very low.Ce is negative anomaly in general while Eu is obviously positive.HREE is enriched in the radiolariancherts,but not distinctly enriched in the siliceous dolostone.The Ce/Ce∗,LaN/CeN ,V/Y rati-os indicate that the cherts are formed in the transition zone from oceanic basin to continental mar-gin.The Th/Sc,Th/U,V/Cr,V/ (V+Ni)ratios indicate that the cherts are mostly formed in the reducing environment,with a small number formed in the oxidation environment.Consider-ing the trace and rare earth elements characteristics and regional evolution of tectonics during Sin-ian period,it is inferred that the cherts are formed in shallow-sea shelf oxygen-enriched environ-ment and anoxic intracontinental taphrogenic trough environmentin the complex continental margin.关键词
大巴山构造带/灯影组/硅质岩系/热水成因Key words
tectonic belts of Daba Mountain/Dengying formation/cherts/hydrothermal origin分类
天文与地球科学引用本文复制引用
赵长缨,段立志,马中豪..上扬子地块北缘灯影组硅质岩系地球化学特征及其成因[J].西北地质,2015,(2):31-42,12.基金项目
国家自然科学基金(41173055),中国地质调查局“环扬子地质流体与低温热液成矿作用研究”(1212011121117)项目资助 （41173055）
