摘要
准噶尔盆地东北缘卡拉麦里地区发育大量花岗质岩体,岩性主要为碱长花岗岩,以及少量石英二长岩和二长花岗岩。以上述3种岩体为研究对象,进行了锆石U-Pb年代学、Hf同位素和岩石地球化学研究。花岗质岩体LA-ICP-MS锆石U-Pb年龄为325~308 Ma,形成时代为晚石炭世。岩石地球化学特征显示其属于准铝质—弱过铝质高钾钙碱性系列,具有高Si、富碱、富K、富Al等特点。碱长花岗岩具有A型花岗岩特征,而石英二长岩和二长花岗岩具有I型花岗岩特征。卡拉麦里晚石炭世花岗质岩体所处构造背景应为由挤压碰撞到拉张的转换时期。物源分析表明:铀矿的铀源来自卡拉麦里花岗质岩体,U含量平均值超过3×10^(-6),Th/U平均值为7.18,具备富铀地质体特征,U迁移量可高达8.26×10^(-6),U平均原始含量为5.46×10^(-6);K 2O/Na 2O值为0.75~1.46,平均值为1.11,FeO/MgO值为1.18~20.73,平均值为5.28,显示其具有较高的陆壳成熟度,表明该地区具有较高的铀成矿潜力。
Large-scale granitoid bodies including alkali-feldspathic granites,and few quartz diorite and diorite granites,are distributed in Kalamaili area,the northeastern margin of Junggar Basin.Zircon U-Pb chronology,Hf isotope and petrological geochemistry were carried out on these granitic bodies.Isotope data and geochemical features indicate that the granites have Late Carboniferous emplacement age and belong to quasi-aluminous to peraluminous high-K calc-alkaline series with the characteristics of high Si,alkali-rich,K-rich,and Al-rich.The alkali-feldspathic granite is A-type,while the quartz diorite and diorite granite are I-type.The Late Carboniferous granite bodies in Kalamaili should be under the tectonic setting which transforms from compression to extension.Provenance analysis indicates that the uranium source of sandstone-type uranium deposit is derived from granodiorite bodies in Kalamaili area.The average U content of these granodiorite exceeds 3×10^(-6) with the mean Th/U value of 7.18,showing the characteristic of U-rich geological body.The transported uranium amount(△U)can be as high as 8.26×10^(-6) and the average paleo U content(U_(0))is 5.46×10^(-6).K_(2)O/Na_(2)O and FeO/MgO values show high continental crustal maturity,indicating that this region has a high potential for uranium mineralization.
作者
耿英英
刘章月
黄少华
何中波
GENG Ying-ying;LIU Zhang-yue;HUANG Shao-hua;HE Zhong-bo(Beijing Research Institute of Uranium Geology,Beijing 100029,China;State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,Beijing 100083,China)
出处
《地球科学与环境学报》
CAS
北大核心
2022年第1期20-41,共22页
Journal of Earth Sciences and Environment
基金
国家自然科学基金项目(41902084)。
