摘要
铀是中国的关键性能源金属和战略矿产资源之一.柴达木盆地与周缘虽然取得了一些铀矿找矿成果,但与之广袤的面积相比仍显不足.在简要介绍柴达木盆地区域铀矿地质背景的基础上,整理并分析了该区典型铀矿床(点)特征和主要中酸性岩浆岩的Th、U含量及锆石U-Pb年龄数据等资料.结果表明,柴达木盆地与周缘铀矿化类型多样、种类齐全,主要为碱性岩(脉)型、花岗伟晶岩型、花岗岩(内带、外带、碱交代)型、火山岩型、层间氧化砂岩型、层间氧化-油气还原砂岩型等.柴达木盆地与周缘"全位"铀成矿模式涵盖了该区可能存在的16种铀矿化类型.铀成矿时代从加里东晚期(436～401 Ma)直至现代.柴达木盆地北缘、南阿尔金和东昆仑构造带在区域地质演化和铀成矿作用的时间上具有一定的一致性,但是由于构造带的抬升剥蚀差异,柴北缘富铀岩浆岩和铀矿化保存最好,其次为南阿尔金,最差的是东昆仑构造带.结合盆缘成矿物质(源)、成矿流体场(运)、山前成矿空间(储)、盆内还原障(保)等成矿条件分析,指出柴达木盆地北部以侏罗系为目标层位的层间氧化砂岩型铀矿远景区有5个,南部和西部以新近系与更新统为目标层位的层间氧化-油气还原砂岩型铀矿远景区有6个.
Abstract
Although some uranium exploration achievements have been discovered in the Qaidam basin and its sur-rounding areas,compared to its vast area,this achievement appears insignificant.On the basis of a brief introduc-tion to the geological background of uranium mining in the Qaidam basin region,information on the characteristics of typical uranium deposits(occurrences)in the region and the Th and U contents of the main neutral-acidic mag-matic rocks and zircon U-Pb age data were collected and collated.The results indicate that the uranium minerali-zation types in and surrounding the Qaidam basin are diverse and complete,mainly including alkaline rock(vein)type,granite pegmatite type,granite(inner zone,outer zone,alkaline metasomatism)type,volcanic rock type,interlayer oxidation(oil and gas reduction)sandstone type,etc.There are 16 possible uranium types in the"all-positions"model of uranium mineralization in and surrounding the Qaidam basin.The currently preserved uranium mineralization period has developed from the late Caledonian(436～401 Ma)to Cenozioc.The northern margin of the Qaidam basin,the southern Altun,and the eastern Kunlun tectonic zones have a certain degree of consistency in regional geological evolution and uranium mineralization times.However,due to the differences in uplift and e-rosion,the uranium mineralization in the northern margin of the Qaidam basin is best preserved,followed by Al-tun,and the worst is the eastern Kunlun tectonic zone.Combining the analysis of the ore-forming materials(source),ore-forming fluid field(transport),ore-forming space(storage)in the front of the mountain,and the reduction barrier(preservation)conditions in the basin,it is pointed out that there are 5 interlayer oxidation sandstone type uranium deposits targeting the Jurassic in the northern part of the Qaidam basin,6 interlayer oxida-tion oil and gas reduction sandstone type uranium deposits targeting the Neogene and Pleistocene in the southern and western regions.
维普
万方数据