浙江江山丁家山组层状硅质岩阴极发光特征及成因探讨

浙江江山中二叠世丁家山组，主要由黑色薄层状硅质岩、硅质粉砂岩、粉砂岩夹微晶灰岩组成。黑色薄层状硅质岩以高SiO2、富Al2O3、富Fe2O3、低TiO2和低MnO为特征，REE含量低，具弱Ce亏损、Tm正异常。硅质岩的阴极发光特征和岩石学特征表明，岩石属于交代成因，原岩可能为含生物碎屑灰岩，岩石硅化前曾发生过白云化作用。地球化学研究表明，硅质来源于正常地下水及陆源硅胶，无热水或火山硅质来源的迹象。

Origin of Bedded Chert from Dingjiashan Formation in Jiangshan Region, Zhejiang Province:evidence from cathodeluminescence

The Dingjiashan Formation of the Middle Permian in Jiangshan,Zhejiang Province is composed of the black lamellar and bedded cherts,siliceous siltstone,and siltstone intercalated with micrite.The black bedded cherts are characterized by high SiO2,rich in Al2O3 and Fe2O3,low TiO2 and MnO,low REE values,Ce deficiency and positive anomaly Tm value.The characteristics of cathodeluminescence and lithology have proved that these siliceous rocks were originated by replacement of sedimentary carbonates,such as bioclastic limestone,dolomitization were took place before silification.The chemical analysis data demonstrate that siliceous matter came from the normal underwater and continental silica gel,not from hydrothermal or volcanic silicon.