新疆翠岭地区雅满苏组含铁硅质岩岩石学特征及成因

针对雅满苏组含铁硅质岩的成岩物质来源和岩石成因,开展了含铁硅质岩的岩石学特征分析和研究。翠岭地区含铁硅质岩赋存于下部细碧岩与上部千枚岩的沉积间断界面,形成时间晚于细碧岩,早于千枚岩,与下部细碧岩具贯入、熔蚀、穿插等接触现象。含铁硅质岩矿物主要由石英、磁铁矿、赤铁矿、针铁矿组成,四者含量占95%以上,含少量绢云母、黑云母、绿帘石及碳酸盐。含铁硅质岩具有高的SiO _2、TFe_2O_3,低的TiO _2、MnO、Al_2O_3含量特征,FeO+TFe_2O_3、SiO _2+TFe_2O_3、K_2O+NaO含量变化和SiO _2/Al_2O_3、SiO _2/(K_2O+Na_2O)比值特征与火山作用和海底热泉有关的硅质岩较类似,Fe/Ti、(Fe+Mn)/Ti和Al/(Al+Fe+Mn)比值具有热水沉积作用形成的含铁硅质岩特征。在Al_2O_3-SiO _2判别图解、Fe-Mn-Al三角图解和Fe-Mn-(Cu+Co+Ni)×10三角图解中,含铁硅质岩均落在热水沉积区域。大多数含铁硅质岩ω(MnO)/ω(TiO _2)比值较高,Al_2O_3含量较低,极少数含铁硅质岩ω(MnO)/ω(TiO _2)比值较低,含量较高,表明物质来源主要为来自大洋底部火山作用的热液局部有陆源碎屑沉积成分的混入。综合翠岭地区的地质和空间分布特征,推测含铁硅质岩的成岩物质来源主要为细碧岩,含有极少量的陆源碎屑物质,属于与火山作用有关的非生物成因类型。

Lithological characteristics and petrogenesis of iron bearing siliceous rocks of Yamansu group in Cuiling area, Xinjiang

In the Emerald Green Ridge area, iron bearing siliceous rocks distributed in the sedimentary discontinuity contact between the lower spilite and the upper phyllite, which were formed later than the spilite and earlier than phyllite, contacting lower spilite with penetration, corrosion, interspersed phenomena.Minerals in iron bearing siliceous rock mainly consist of quartz, magnetite, hematite and goethite, four content more than 95%, and contain a few of sericite, black mica, epidote and carbonate. Iron bearing siliceous rocks have high SiO₂, TFe₂O₃, TiO₂, MnO, Al₂O₃ content features. Fe/Ti, (Fe+Mn)/Ti and Al/(Al, Fe and Mn) ratio has the characteristics of iron bearing siliceous rocks formed by hydrothermal sedimentation. The Al₂O₃-SiO₂ discrimination diagrams, Fe-Mn-Al triangle illustration and Fe-Mn-(Cu, Co and Ni) × 10 triangular diagram, all iron bearing siliceous rocks are in hot water deposition area. In most iron bearing siliceous rocks, (MnO)/omega omega (TiO₂) ratio is higher, and Al₂O₃ content is low, while (MnO)/omega omega (TiO₂) ratio is low, and content is higher in a handful of iron bearing siliceous rocks, which show that the material source mainly originated from the hydrotherm associated with volcanism in the bottom of the ocean and locally mixed with the composition of terrigenous clastic sedimentary. Based on above the geological and spatial distribution characteristics in Cuiling area, it is speculated that diagenetic material source of iron bearing siliceous rock mainly originated from spilite and few of terrigenous detrital material.The genetic type of iron bearing siliceous rock belongs to the abiotic origin associated with volcanism.