【摘要】 安徽巢湖地区孤峰组地层为一套层状硅质岩与泥质岩交互沉积岩系,对其成因一直存在不同的认识。本文通过详细的野外地质调查和岩相学研究,以及常量元素和稀土元素等地球化学研究表明,该区硅质岩在Al-Fe-Mn三角图和SiO2-Al2O3,SiO2-MgO双变量图解中都落到生物成因的硅质岩范围内。δCe具有正异常,轻稀土富集,这些特征表明本区硅质岩属海水生物沉积成因。硅质岩的ΣREE值在22.62~209.03μg/g之间,平均值为88.58μg/g;Ceanom值的范围在0.20~2.78,平均值为1.70;(La/Yb)N值在0.39~2.80之间,平均值为1.01,这些地球化学指标揭示了本区硅质岩形成于深水缺氧环境。更多还原

【Abstract】 Gufeng Formation is a set of sedimentary rocks composed of bedded siliceous rocks and argillaceous rocks in Chaohu region,Anhui Province.The origin for the siliceous rocks has been debated for a long time.In this paper,we report the details of field and petrographic research,data of major elements,rare earth elements compositions of these rocks.Our results suggest that in the Al-Fe-Mn ternary,and the SiO2-Al2O3,SiO2-MgO binary discriminant diagrams,these rocks fall in the biochemicallydeposited area.These siliceous rocks show positive Ce anomaly,and a comparatively enrichment of LREE,which indicate a biochemically-deposited origin for these rocks.The siliceous rocks have the total REE contents of 22.62~209.03μg/g,with an average of 88.58μg/g;the Ceanomvalues are 0.20~2.78,with an average of 1.70;the(La/Yb)Nvalues are 0.39~2.80,with an average of 1.01.All these geochemical characteristics suggest that these siliceous rocks were deposited in a deep-water and anoxic condition.更多还原