广东长排铀矿床成矿流体特征

长排铀矿床位于广东长江铀矿田内，矿体主要赋存在北北西向硅化断裂带内及其两侧的蚀变花岗岩中。流体包裹体显微测温和激光拉曼光谱分析表明，成矿流体为中低温、中低盐度的含CO2、CH4和H2的流体。铀成矿期流体包裹体均一温度多集中于120~250 ℃，盐度为04%~102%。氢、氧同位素分析表明，成矿流体可能来源于深部，后期有大气降水的加入。成矿期方解石的δ13C值大多数集中于-91‰~-82‰，以深源碳为主。综合分析认为，长排铀矿床属于中低温热液脉型铀矿床。成矿流体经历了沸腾作用，使CO2等挥发分逃逸，这可能是长排铀矿床铀矿沉淀、富集的主要原因。

Characteristics of Ore forming Fluids of the Changpai Uranium Deposit in Guangdong Province

The Changpai uranium deposit is located in the Changjiang ore field in northern Guangdong Pro vince. The uranium orebodies are controlled by the NNW trending silicified fracture zones and hosted within both the fracture zones and adjacent altered granites. Microthermometric measurements and Laser Raman Spectrum analysis indicate that the ore forming fluids of the Changpai uranium deposit are of medium low temperature, medium low salinity and contain volatiles including CO2, CH4 and H2. The homogenization temperatures of the ore forming fluids range from 120 to 250 ℃ while the salinities range from 04% to 102%. Hydrogen and oxygen isotopic systems of quartz indicate that the ore forming fluids are mainly derived from magmatic water in the early stage but mixed with meteoric water in the late stage. The δ13C values of calcite from the mineralization stage are mostly from -91‰ to -82‰，signifying deep sourced carbon in this deposit. On the basis of the aforementioned analyses, it is suggested that the Changpai uranium deposit is a medium low temperature hydrothermal vein type uranium deposit. Fluid boiling of the ore forming fluids and consequent escape of the volatile (eg, CO2) components resulted in the precipitation of pitchblende and other uranium minerals.