相山铀矿田铀源的地球化学证据

相山矿田矿石、沥青铀矿及伴生的黄铁矿的铅同位素具有明显的异常铅特征，成矿物质源区年龄为140Ma，与该区碎斑熔岩的年龄一致，说明铀源系由火山岩提供。矿石中U、Th、Mo、P的分布特征显示成矿铀源来自围岩。水-岩反应的模拟实验结果表明，铀成矿热液可以由本区火山岩与地下水在成矿期地质地热背景条件下的相互作用产生。

URANIUM SOURCES OF THE XIANGSHAN URANIUM ORE-FIELD:GEOCHEMICAL EVIDENCE

The Xiangshan uranium ore-field, located in Jiangxi Province, SE China, is one of the largest volcanic rock-related uranium ore-fields in our country. In the ore-field, the lead isotopic compositions of ores, pitchblende and pyrite associated with uranium materialization, possess obvious anomalous lead characteristics, and the calculated two-stage model age for the source materials is 140 Ma, just in consistence with the age of pyroclastic lavas in the area studied. The lead isotopic evidence suggests that uranium in the orefield be derived from local volcanic rocks. The concentration distribution patterns of uranium, thorium, molybdenum, and phosphorus in ores imply that uranium originated from wall rocks. Simulation experiment on water-rock interaction showed that the uranium ore-forming fluid could be formed from interactions between the Xiangshan volcanic rocks and groundwater under anomalously high geothermal background conditions during the metallogenic period.