相山、下庄铀矿田稀土元素特征对比

CORRELATION OF REE FEATURES BETWEEN XIANGSHAN AND XIAZHUANG UANIUM ORE FIELDS

为了从大的区域上探讨铀矿的成矿作用,本文分别采集了相山、下庄两个铀矿田的围岩和矿石样品并用ICP-M S方法进行测定。结果发现两个铀矿田的围岩REE特征均为LREE富集型,具有明显的负铕异常。相山矿田的矿石富集REE特别是HREE,并且与铀含量呈正相关关系,矿石和围岩的负铕异常相同;下庄矿田的矿石亏损REE尤其是LREE,具有比围岩更强烈的负铕异常。认为两矿田的围岩都是由沉积岩为源岩的地壳物质部分熔融形成的,ΣCO2是两个铀矿田的主要矿化剂,也是铀和REE运移的主要载体,造成两矿石REE特征不同的主要原因是相山矿田围岩蚀变以酸性为主而下庄铀矿田围岩蚀变以碱性为主。

Sample of the host rock and ore in Xiangshan and Xiazhuang Uranium Ore-field are collected and analyzed by ICP-MS. The result shows that the REE features of host rocks in the two uranium ore-fields are rich in LREE with Eu negative abnormality. The Xiangshan ores is rich in REE,especially in HREE,and the content of REE and U is directly propotional and they have the same Eu negative abnormality as the host rocks. However Xiazhuang ores is depleted in REE,especially depleted in LREE, and has higher U negative abnormality than the host rocks. The host rocks of the two ore fields were all formed by the partial melting of crust materials of sedimentary rocks. ∑CO2 is the major mineralizer and carrier for the migration of U and REE. The main reason for the difference in the REE features of ore for the two uranium ore-fields is that the wall-rock alternations of Xiangshan uranium field is mainly acid, on the contrary, that of Xiazhuang uranium field is alkaline.