【摘要】 产于火山岩中的沥青铀矿床常伴生Mo、Cu、Pb、Zn、Au、Ag等元素,形成铀多金属矿床和矿田。文中在认识花岗岩型铀多金属矿田成因的基础上,对华北沽源盆地和华南仁差盆地的铀多金属矿田的主要矿床成矿特征进行对比研究。结果表明此类矿床是火山岩地层之后的热液矿床,其形成与岩浆喷发过程无关。热液成矿作用一般有早、晚两期:早期主要为亲硫元素,形成金属硫化物矿床;晚期为亲氧元素成矿,形成沥青铀矿床。盆地的沉降使得早期金属硫化物成矿壳层位置下降,从而缩短了与晚期重熔界面之间的距离,造成晚期氧化物(沥青铀矿)成矿壳层在空间上与其重叠或靠近,从而形成氧(沥青铀矿)硫(金属硫化物)复合矿床(矿田)。更多还原

【Abstract】 Chalcophiles as Mo,Cu,Pb,Zn,Au,Ag,etc.used to be found enriched in pitchblende uranium deposits in volcanic basins,forming so called‘volcanic-type’uranium-polymetal deposits and ore-field.On the basis of studies of granite origin and‘granite-type’uranium-polymetal ore-field,the authors of this paper try to investigate the formation mechanism of such type of ore-field by comparing the principal ore-deposits in both Guyuan and Rencha volcanic basins in the northern and southern China,respectively.The research result suggests that uranium-polymetal deposits were formed in the post-magma hydrothermal stage rather than the magma eruption period.The formation of a uranium-polymetal deposit commonly underwent two mineralization processes,i.e.,chalcophile-mineralization in the early stage,forming polymetallic sulphide deposit,and oxyphile-mineralization in the later stage,forming uranium deposit.With subsidence of basin after the former process,the polymetal mineralization layer was pressed downward thus to be closer to the latter stage magma layer that produced U-bearing hydrothermal fluid,giving rise to the possibility that the product of the late ore-forming stage,i.e.uranium mineralization layer overlapped that of the former to form a compound oxyphile-chalcophile ore deposit or ore-field.更多还原