竹山下矿床中的早期高温铀成矿作用

The Early High-temperature Uranium Mineralization in Zhusanxia Deposit

在下庄矿田铀成矿作用研究过程中发现 ,竹山下矿床中存在一期早期气热高温铀成矿作用。通过竹山下矿床及外围基性岩岩墙的产状、矿物组合、化学成分等对比研究 ,推测这期成矿作用的气热高温热液来源于下庄矿田存在的花岗岩 ( 15 0～ 15 5Ma)岩浆气液 ,这种气液应是温度在 5 0 0℃以上、富含B ,W ,U ,K等元素的超临界流体。基性岩脉在经过这种超临界流体蚀变交代作用后 ,Na2 O含量大大降低 ,表现为Na2 O的含量明显低于K2 O的含量 ,并出现弱铕亏损。这期成矿作用以出现晶质铀矿、电气石 (多为镁电气石 )、白钨矿、磁铁矿等矿物组合为特征 ,成矿年龄为 14 6～ 165 .5Ma。

The early high-temperature uranium mineralzaton had been discovered from a series of studies about the uranium mineralizaton in Xiazhuang ore-field. Based on the studies of the geological occurrence and mineral compositions and chemical compositions of the green pneumato-hydrothermal altered diorites in Zhusanxia deposit and vicinity, this article has concluded that the pneumato-hydrothermal solution of the early high temperature uranium mineralzaton comes from the granite which age is about 150～155 Ma, and is SCF(Super Critical Flow) of 500 ℃ above and rich in K、B、W and U. After altered by the SCF, these diorites has low Na_2O , Na_2O<K_2O and Eu weak loss. The early high-temperature uranium of the area is characterized with .the minerals assemblage of uraninite, tourmaline, scheelite and magnetite, and with age of 146～165.5 Ma.