内蒙古多伦县核桃坝地区火山岩型铀成矿特征及找矿标志

Characteristics of Volcanic-Type Uranium-Ore Forming and Sign for Uranium Searching at Hetaoba Area,Duolun County,Inner Mongolia

核桃坝位于内蒙古多伦县与正蓝旗接壤部位,位于内蒙古海西褶皱带和华北陆块北缘接触部位,新发现的铀矿产于晚侏罗世-早白垩世榛子山火山机构南部弧形火山隆起带酸性火山岩中,为与中生代火山岩有关的热液型铀矿化。近年来,该区铀矿找矿勘查和成矿研究取得了一定突破,核桃坝铀矿点扩大为小型铀矿床,初步认为受流纹斑岩次火山岩体、SN-NE向构造控制的隐伏铀矿化。综合调查发现,中生代火山机构隆起与洼陷过渡带中火山构造与控盆、控岩(次火山岩)断裂构造交汇处为铀矿化有利区;高岭土化、钾化、硅化、褐铁矿化构造蚀变带,土壤瞬时氡气异常晕(带),物探测量反演的高阻和磁化率陡变部位等多指标组合构成了铀矿化找矿标志。

Hetaoba area is located in the connecting part between Duolun and Zhenglanqi of Xilinguole of Inner Mongolia,and tectonically sits in the connecting part of Inner Mongolia Hercynian tectonic-magmatic belt and the north of the North China craton.A new found uranium deposit exists atthe acidic volcanic rocks that are located at the arc belt of the south of Mesozoic Zhenzishan Mountain likely as a kind of hydrothermal-type uranium deposit relating to the Mesozoic volcanic rocks.This uranium deposit is formed in the node of subvolcanic rocks and controlled by the SN-NE trenched fault structure.Through the preliminary studies we found that the transitive belt of Mesozoic volcanic uplift and sag as well as the intersection of multi faults,which controlling the volcanic basin and subvolcanic rocks,are favorable for uranium mineralization.Other signs such as kaolinization,potassium alteration,silicification,and limonitization tectonic belt,and abnormal ring of earth instant Rn anomaly,high electronic resistance,and strong variety of magnetic ratio constitute uranium ore-forming indicator for further uranium survey.