淮南寒武系土坝组硅质层赋存规律及成因

Occurrence Regularity and Their Origin of Siliceous Layer in Huainan Cambrian Tuba Formation

通过野外地质调查,查明硅质层平面和垂向分布,分析了岩样及显微结构特征,总结了地区硅质来源及其成因。结果表明:受长期构造地质运动改造与风化剥蚀,沉积间断,硅质层与上覆贾汪组泥页岩假整合接触,硅质突出,蜂窝状构造较发育;层面硅质条带是早期成岩过程中深源硅质热水裂隙发育形成,沿走向伸展较远,近南北硅质条带由后期陆源黏土矿物转化的溶解硅充填裂隙形成,在垂向上延伸有一定局限性;薄片中大量悬浮交代菱形白云石颗粒,是热液相关的硅化作用的结果,石英颗粒保留有原有白云石颗粒形态,局部残余白云石晶体,具典型热水交代成因特征。

Through field geological survey,the plane and vertical distribution of siliceous layers were identified;rock samples and microstructure characteristics were analyzed,and the source and genesis of siliceous in this area were summarized.The results show that the siliceous layer is disintegrated with the overlying mud shale of Jiawang Formation due to the long-term tectonic and geological movement,weathering and denudation.The siliceous layer is prominent and the honeycomb structure is relatively developed.The stratified siliceous bands were formed by deep siliceous hydrothermal fissure in early diagenetic process and extended far along strike.The siliceous bands near north and south were formed by the dissolved siliceous fissure filled by late terrigenous clay mineral conversion,and had some limitations in vertical extension.A large number of suspended metasomatic prismatic dolomite particles are the result of hydrothermal silicification.The quartz particles retain the original dolomite particle morphology and local residual dolomite crystals,with typical characteristics of hydrothermal metasomatic origin.