内蒙古丰镇市油篓山一带侏罗纪岩体的岩石学及地球化学特征

Petrological and geochemical characteristics of Jurassic rocks in the Youloushan area of Fengzhen city,Inner Mongolia

在1:5万内蒙古察哈尔右翼前旗、隆盛庄、西官村及永善庄4幅区域矿产地质调查的基础上,对以油篓山为代表的侏罗纪岩体从岩石学、岩石化学、稀土及微量元素等特征方面进行了初步研究。采用富集系数来讨论元素富集成矿问题,侏罗纪岩体富集—强富集的元素有Ag、Pb、Zn、As、Sn、Sb、Hg、W、Bi和Mo,说明侏罗纪岩浆活动为成矿提供了含矿热液。岩石化学及地球化学特征研究表明,测区侏罗纪岩体属钙碱性系列的铝饱和—过饱和类型,显示为碰撞阶段岩浆作用产物;似斑状花岗岩岩体稀土元素配分曲线向右陡倾,倾角较陡,说明轻、重稀土分离明显;石英斑岩岩体稀土元素配分曲线右倾,倾角平缓,表明轻、重稀土未有明显分馏。

On the basis of the 1＊ 50 000 regional geological survey of Chahar Right Front Banner, Longsheng vil-lage ,Xiguan village and Yongshan village, the authors preliminarily studied the characteristics of petrology, litho- chemistry of rare earth and trace elements for Jurassic rocks in the Youloushan area. Enrichment factors are used to study mineralization. The enrichment and strong enrichment elements of Jurassic rocks are Ag, P b, Zn, As, Sn, Sb, Hg, W, Bi and Mo, which shows that Jurassic magmatic activity provides the metallogenic hydrotherm. The characteristics of lithochemistry and geochemistry show that Jurassic rocks belong to aluminium saturation of super-saturation type of calc-alkaline series, and are the products in the encounter stage of magmatism. The rare earth elements distribution curve of porphyritic granite rocks exhibits a rightward steep dip, which shows the obvi-ous separation between light and heavy rare earth elements. The rare earth elements distribution curve of quartz porphyry rocks exhibits a rightward gentle heeling, which shows an unobvious fractionation between light and heavy rare earth elements.