Characteristics URANIUM Under Diagenetic Mineralization And Alteration Era

Xiazhuang uranium ore-field is located in the Guidong granite complex innorthern Guangdong province, which is one of the important granite uraniumore-fields in China. After collecting the geological data and the predecessor researchresults, we has used two isotope dating methods of U-Pb and40Ar-39Ar as theoreticalbasis, discussed on diagenetic age, alteration age and ore-forming age, then given aset of relatively complete isotope chronology research results. it includes thefollowing respects:(1) Guidong granite complex is consist of Maofeng rock, Xiazhuang rock, Luxirock, Guiweishan rock, Chendong rock and Yanzhuang rock, Zircon LA-ICP-MSU-Pb ages of results are235.6±0.62Ma,236.7±0.72Ma,237.3±0.93Ma,223.9±1.7Ma,151.48±0.43,161.3±0.57Ma, these results show that Guidong graniterock should be a complex rock formed in Indosinian epoch to Yanshan epoch. In thispaper, we have taken ziron LA-ICP-MS U-Pb dating for Guiweishan rock, Chendongrock and Yanzhuang rock in the first time.(2) There are other rocks distributed surrounding Guidong granite rock, whichinclude Gaoxi, Donggualing, Wuliting, Luokeng, Shangdong, Dazhuang, etc. ZirconLA-ICP-MS U-Pb ages of results are442.9±0.89Ma,417.9±1.1Ma,239.1±0.95Ma,213.7±1.8Ma,25.8±1.6Ma,420.0±1.6Ma. This shows the intrusive era of peripheryrocks surrounding Guidong granite rock is mainly Caledonian to Indosinian. So, wehave finished ziron LA-ICP-MS U-Pb dating for Guidong complex rock and allperiphery rocks, after all, the diagenetic ages are defined more accurately and moresymtematicly.(3) After collecting pitchblende and uranium minerals from Shituling,Zhushanxia, Xianshi and other characteristical deposits, we have taken U-Pb isotopedating, which the ages of results show that there are two stages of ore-forming age inXiazhuang uranium ore-field, the early age is131Ma, the era is Early CretaceousEpoch and the late is78～93Ma, the era is Late Cretaceous Epoch.(4) With40Ar-39Ar isotopic dating method as the theoretical basis, we have applied step heating technology to analyze the forming ages of theHuangpi-Zhuangguangying diabase and the Xiazhuang–Qixia diabase, the results are139.68±1.83Ma,108.7±2.54Ma, which shows the invasion of east-west diabaseoccurred in the early stage of Early Cretaceous and the late stage of Early Cretaceous.Combining previous research results, the intrusion of another diabase-porphyrite anddiorite porphyrite in NNE, NEE direction is occurred in88~93Ma.(5) For the study of alteration age, we have analyzed potash feldspars fromShituling deposit and Zhushanxia deposit, the results of40Ar-39Ar dating are144.09±0.82Ma and88.12±4.27Ma, which shows the alteration age in Xiazhuanguranium ore-field has two stages at least, and it has a corresponding relation with theinvasion age of diabases and ore-forming age.All in all, we have organicly studied diagenetic age, alteration age andore-forming age together in this paper, then basically determined a general timeevolution lattice, which can help us to deepen the understanding of the mineralization.