河北沽源—多伦地区中生代含铀火山岩地球化学

沽源和多伦地区是燕辽多金属成矿带的重要组成部分，中生界主要发育上侏罗统白旗组、张家口组，下白垩统大北沟组和花吉营组。张家口组火山岩分布广、厚度大，是铀（钼）矿床的主要含矿主岩。中生代火山岩属于钙碱性系列，化学成分富硅、偏碱，δ值1.17-7.60。稀土元素特征反映火山岩有壳幔混合和壳源改造两种成因。火山岩形成于弱造山环境，其年龄与库拉—太平洋板块向亚洲板块俯冲的时间吻合。张家口组酸性火山岩具有我国相山产铀火山杂岩富硅、富钾，铕极亏损的地球化学特征。

Geochemistry of Mesozoic uranium-bearing volcanic rocks in Guyuan-Duolun area, Hebei Province

Guyuan-Duolun Area is an important part of Yanliao polymetallic metallogenic belt. Mesozoic volcanic strata are mainly composed of Baiqi Formation and Zhangjiakou Formation of upper Jurassic series, Dabeigou and Huajiying Formation of lower Cretaceous series. The volcanic rocks of Zhangjiakou Formation are developed widely in this area and are the main uranium-bearing host rocks. Mesozoic volcanic rocks in this area belong to the calc-alkaline series rich in silicon and alkaline, 8 values range from 1.17 to 7.60. The REE features indicate that the volcanic rocks can be divided into two genetic types, i.e. crust -mantle mixture type and crust reformation type. The volcanic rocks formed in a weak orogenic environment,and their age corresponds to the time when Kula-Pacific plate subducted to Asia plate. The acid volcanic rocks of Zhangjiakou Formation show the geochemical characteristics of Xiangshan uranium-occurring igneous complex which is rich in silicon and alkaline, and depleted in Eu.