铀成矿机理的统一性探讨

Discuss on the unity of uranium metallogenic mechanism

关键词:  铀矿  地核  地幔柱  洋岛玄武岩  板内玄武岩  A型花岗岩  高分异花岗岩

Key words:  uranium ore  the earth's core  mantle plume  oceanic island basalt  intraplate basalt  A-type granite  highly differentiated granite

摘要:

为探讨不同类型铀矿床是否可能本质上都是地幔柱作用的产物，在“全球热液铀矿成因理论”和“热点铀成矿理论”等前人研究基础之上，结合岩浆岩锆石铀、钍含量研究初步揭示了：（1）铀、钍主要富集于外地核；（2）洋岛玄武岩、板内玄武岩、高分异花岗岩及伟晶岩型铀矿可能为地幔柱产物。对比国内多种类型铀矿床科研成果，总结发现有一定数量的铀矿床与洋岛玄武岩、板内玄武岩、A型花岗岩以及高分异花岗岩紧密伴生，成矿与成岩时空基本耦合。如四川攀枝花大田混合岩型铀矿和松辽盆地钱家店–白兴吐砂岩型铀矿伴生两类玄武岩；甘肃芨岭钠交代型铀矿和陕西商丹伟晶岩型铀矿区伴生两类花岗岩；粤北诸广–贵东花岗岩型铀矿区、赣南多类型铀矿区和江西相山、新疆白杨河火山岩型铀矿区伴生以上四类岩石类型。分析认为上述岩石类型可能是由地幔柱生成并起着导矿或导矿兼储矿的关键作用，据此提出铀矿“核源–地幔柱”成因认识，即：外地核是铀元素的主要发源地，地幔柱是铀运移的统一通道，铀成矿过程可能是外地核中的金属铀呈铀氢化物或铀合金氢化物等形式沿地幔柱上升迁移，直至在浅部地质体氧化聚集成固态铀矿物的过程。

Abstract:

To investigate whether the different type uranium deposit in essence is a product of mantle plume effect, on the basis of previous studies of "global hydrothermal uranium genesis theory" and "hot spot uranium mineralization theory", etc, and combined with the content of uranium and thorium in zircon magmatic rocks, it is suggested that uranium and thorium are mainly enriched in outer core and oceanic island basalt, intraplate basalt, highly differentiated granite and pegmatolite type uranium deposits, which may be the products of mantle plume. By comparing the research results of various types of uranium deposits in China, it is concluded that a certain number of uranium deposits are closely associated with oceanic island basalt, intraplate basalt, A-type granite and highly differentiated granite, and that mineralization and diagenesis are spatiotemporal coupling. The two types of basalts can be associated with the Datian mixed rock type uranium deposit in Panzhihua, Sichuan Province and the Qianjiadian-Baixingtou sandstone type uranium deposit in Songliao Basin, The two types of granites include the Jiling sodium metasomatic uranium deposit in Gansu Province and the Shangdan pegmatite uranium deposit in Shaanxi Province. And the four types of rock bodies can be associated with the Zhuguang-Guidong granite lithologic uranium deposit area in northern Guangdong, the multi-type uranium deposit area in south of Jiangxi Province, and volcanic rock type uranium deposits in Xiangshan, Jiangxi and Baiyanhe, Xinjiang. Based on the analysis, it is suggested that these plutons may be generated by the mantle plume and play the key role of ore guide or ore guide and deposit. Therefore, it is suggested that the origin of the uranium deposit is "core sources-mantle plume", that is, the outer core is the main origin of uranium element, and the mantle plume is the unified channel of uranium migration. The uranium mineralization process may be that the metallic uranium in the outer core ascends and migrates along the mantle plume in the form of uranium hydride or uranium alloy hydride, etc, until it oxidizes and aggregates into solid uranium minerals in the shallow geological body.