新疆柯柯亚一带晚石炭世硅质岩成因分析

Origin of Silicalites of Upper Carboniferous in the Neighborhood of Kekeya, Xinjiang Uygurautonomous Region

新疆柯柯亚一带晚石炭世硅质岩分布极为广泛,通过野外地质填图及矿产调查过程中的详细观察和硅质岩岩石学特征分析,并根据硅质岩具有低SiO2、K2O、P2O5及HREE;高Al2O3、FeO、MgO、K2O+Na2O、TiO、∑REE;SiO2/Al2O3、SiO2/(Na2O+K2O)值分别为11～25和37～74;Fe/Ti值小于20、(Fe+Mn)/Ti值小于15、Si/(Si+Al+Fe)值小于0.9等特征,认为这些硅质岩为火山成因。而且Th/Sc、Th/U和δCe等值及稀土配分曲线和TiO2-Al2O3图解也明确指示了硅质岩属火山成因类型。

The siliceous rocks Upper Carboniferous in the neighborhood of Kekeya, Xinjiang distributes widely. The field geological mapping, commodity survey as well as the analyses on petrology of the siliceous rocks ,and they have geochemical characteristics of low SiO2, K2O, P2O5 and HREE content, high Al2O3, FeO, MgO, K2O＋Na2O, TiO2 and 52 REE content, SiO2/Al2O3, SiO2/（Na2O＋K2O） difference is 11- 25 and 37- 74, Fe/Ti ratio less than 20, （Fe＋Mn）/Ti ratio less than 15, Si/（Si＋Al＋ Fe） ratio less than 0.9,and Th/Sc, Th/U ratio and 8 Ce as well as chondritenormalized REE curve and TiO2--Al2O3 diagram all indicates that the genesis of these siliceous rocks is volcano.