桃山-诸广铀成矿带成岩成矿年代学研究进展

桃山-诸广铀成矿带是中国重要的花岗岩型铀成矿带,产铀花岗岩体主要有桃山复式岩体、诸广山复式岩体(南部)、贵东复式岩体(东部)。对铀成矿带内近年来与铀成矿关系密切的花岗岩、基性岩和铀矿化作用的年代学数据进行收集,总结带内成岩成矿年代学研究进展,进而分析存在的主要问题。统计结果表明,近年来高精度的年代学数据一定程度上提高了年代学的精度,促进了对花岗岩、基性岩与铀成矿关系的认识。但是,带内年代学数据主要存在以下问题:(1)花岗岩锆石U-Pb测年结果存在数据偏少、平均标准权重偏差(mean squared weighted deviation, MSWD)高、高铀数据未剔除等问题,且不能为复式岩体的时序的厘定提供依据;(2)基性岩脉多采用Ar-Ar法(易受后期蚀变或热时间影响)和高精度U-Pb法(基性岩浆往往难以结晶出大量锆石);(3)铀成矿年龄测试方法易受检测限、标准样品、高铀效应的影响。综上所述,尽管近年来高精度年代学深化了对铀成作用的认识,但是年代学的测试方法、数据处理等方面仍需要解决。

Research progress of chronology in diagenesis and mineralization , Taoshan-Zhuguang uranium metallogenic belt

Taoshan-Zhuguang uranium metallogenic belt, an important granite-type uranium metallogenic belt in China, mainly conclude Taoshan, southern Zhuguangshan and Guidong complexes which produce uranium. In this paper, geochronological data of granite, mafic veins and uranium mineralization in recent years within this belt were collected. In addition, research progress about the geochronology of diagenesis and mineralization within this belt were summarized and main existing problems were analyzed. Statistical results show that the high-precision chronological data in recent years have improved the accuracy of chronology to a certain extent and promoted our understanding of the relationship between granite, mafic veins and uranium mineralization. However, geochronological data within this belt mainly have the problems in the following: (1) there are some problems about zircon U-Pb dating results in granite, such as lack of data, high NSWD and undeleted high uranium data, which cannot provide a basis for the determination of the time series of the complex massif. (2) Ar-Ar method (susceptible to late alteration or thermal time) and the high-precision U-Pb method (difficult to crystalize a large number of zircons from the mafic magma) are commonly used in the mafic veins. (3) Testing methods to uranium metallogenic ages are susceptible to the detecting limit, standard samples and high uranium effects. In summary, although high-precision geochronology in recent years has deepened our understanding of uranium formation in recent, the testing methods and data processing of geochronology still need to be solved.