新疆白杨河铀铍钼矿床中基性岩脉形成时代及其对铀成矿的制约  

GEOCHRONOLOGICAL STUDY OF MEDIUM-MAFIC DYKES AND ITS CONSTRAINT ON URANIUM MINERALIZATION OF THE BAIYANGHE URANIUM-BERYLLIUM-MOLYBDENUM DEPOSIT IN XINJIANG

作　　者：张浩浩 王果[1] 杨文龙[1] 鲁克改[1] 张雷[1] Zhang Haohao;Wang Guo;Yang Wenlong;Lu Kegai;Zhang Lei(The No.216 Geologic Party,CNNC,Urumqi,Xinjiang 830011,China)

机构地区：[1]核工业二一六大队

出　　处：《矿物岩石》2019年第4期18-25,共8页Mineralogy and Petrology

基　　金：国家自然科学基金项目(41272100);新疆和布克赛尔县白杨河矿床外围铀-多金属矿调查评价(201818-1)

摘　　要：新疆白杨河铀铍钼矿床独特的元素组合世界罕见。铀铍钼矿体主要产于杨庄花岗斑岩体与塔尔巴哈台组(D3t)火山岩接触带上,成矿与中基性岩脉有密切的关系。本次研究了与铀成矿关系密切的中基性岩脉的岩石学、岩石化学、微量元素地球化学、稀土元素地球化学特征,同位素定年等,探讨了中基性岩脉的形成时代、成因类型及形成环境。对区内与铀矿相伴产出的4条较大的中基性脉岩,本次获得215 Ma,216 Ma,217 Ma和203 Ma 4个年龄数据,属印支晚期到燕山早期形成;中基性脉岩具有不相容元素(K,Rb,Ba,Sa,LEE)富集,高场强元素(Nb,Ta,Ti,Zr,Hf)亏损的特点,暗示岩浆源自与俯冲作用有关的交代地幔,属中亚造山带后碰撞阶段造山期后伸展环境下形成的。中基性脉岩在空间上与铀矿体分布密切相关,时间上与铀成矿年龄(197.8±2.8 Ma^237.8±3.3 Ma)相当,认为铀成矿作用与中基性岩脉侵位而引发的热液活动有关。The uranium beryllium molybdenum ore bodies mainly occur in the contact zone between Yangzhuang granite porphyry and Tarbahatai Formation(D3 t) volcanic rocks in the Baiyanghe area of Xinjiang,and closely related to the medium-mafic dykes.Petrological and petrochemical study,zircon U-Pb dating,major-and trace-element composition analyses of the medium-mafic dykes in the deposit are carried out in order to provide constrain for the diagenetic age, petrogenesis and diagenetic environment of the deposit. LA-ICP-MS zircon U-Pb dating for the medium-mafic dykes yields the ages of 215 Ma,216 Ma,217 Ma and 203 Ma respectively,which lasts from late Indosinian to early Yanshanian period.Geochemical analyses show that the medium-mafic dykes are rich in incompatible elements(K,Rb,Ba,Sa,LEE) and poor in high-field strength elements(Nb,Ta,Ti,Zr,Hf),suggesting that magma was originated from metasomatism mantle related to subduction,i.e.in the post-collision and post-extension environment of the central Asian orogenic belt.The emplacement time of the medium-mafic dykes is in accordance with the uranium mineralization age(197.8±2.8 Ma-237.8±3.3 Ma), therefore, the formation of diabase dykes plays an important role in uranium mineralization through the incidental hydrothermal activity.

关 键 词：铀-铁-钼矿床 中基性脉岩 成矿作用 新疆白杨河 

分 类 号：P597.3[天文地球—地球化学]