摘要
盆地内铀矿床中的矿石铅同位素组成表明,其铅同位素比值较正常铅低得多,且与基底岩石及火山岩的岩石铅同位素组成接近;邻区其他金属矿床中的矿石铅同位素组成亦具类似特点。研究结果表明,这种铅系来自基底岩石,是在低μ值(μ_1=5.60)环境中演化的结果;火山岩阶段的μ值(μ_2=11.87)则大大提高,说明了铀元素从基底岩石到火山岩、再到铀矿化,构成了一个逐步富集的演化体系。火山岩是盆地內铀成矿的直接供铀者,是该区域寻找铀矿的远景目标。
The isotopic composition of ore leal from uranium deposits in the Guyuan volcanic basin sho ws that their lead isotope ratios are lower than normal lead ratios, and close to the isotopic composition of rock lead from the basement and volccEic rocks. Their model ages (singlestage evolution) are very old and deviate from the actual uranium minerogenetic epoch. The isotopic composition of ore lead from other metallic ore deposits in the adjacent area also has similar characteristics. Research results show that this kind of lead was derived from the basement rocks and experienced evolution in a lower-μ(μ1 = 5.60) environment. Higher μ(μ,2 = 11.87) in the volcanic rock stage indicates such an evolution that uranium was exported from the basement rocks into volcanic rocks until uranium mineralization. The gain and loss of uranium in all kinds of rocks have been calculated on the basis of the evolutional principle of a uranium-lead isotope system. It is evident that the volcanic rocks are the direct contributor of uranium to mineralization in the basin, and thus are the prospective target in search of uranium deposits in this
出处
《地球化学》
CAS
CSCD
北大核心
1990年第4期286-295,共10页
Geochimica
