粤东金坑锡铜多金属矿区花岗岩锆石U-Pb年龄和辉钼矿Re-Os年龄及其地质意义

广东揭西县金坑铜锡多金属矿床位于粤东地区西北部莲花山断裂带南西段,是粤东锡铜多金属成矿带近年来发现的一处中—大型铜锡铅锌多金属矿床。采用LA-ICP-MS锆石U-Pb法和辉钼矿Re-Os法对矿区与成矿有关的细粒花岗岩及与锡石共生的辉钼矿进行定年,获得该矿床成岩年龄为(141.0±0.3)Ma,辉钼矿Re-Os同位素年龄为(141.3±1.0)Ma,两者年龄接近,表明成岩成矿关系最为密切。并结合细粒花岗岩主微量元素分析结果表明细粒花岗岩具有高硅富碱特点,属于高分异的I型花岗岩,这种岩浆演化末端产物细粒花岗岩有利于成矿金属元素富集,为本区成矿提供巨量的物源与热源。结合成岩成矿年龄研究与主微量分析,初步认为成矿地质体为早白垩世细粒花岗岩,并探讨该矿床的成因及其成矿动力学背景。

Zircon U-Pb and molybdenite Re-Os dating and its geological significance of the Jinkeng tin-copper polymetallic deposit, eastern Guangdong

The gold pit copper tin polymetallic deposit in Jiexi county, Guangdong Province is located in the south west section of Lianhuashan fault zone in the eastern part of Guangdong Province.It is a large copper-tin-lead-zinc polymetallic deposit found in the copper-polymetallic metallogenic belt in eastern Guangdong Province.The LA-ICP-MS U-Pb zircon dating shown that the fine-grained granite''s diagenetic age is 141.0±0.3 Ma, and the Re-Os isotopic measurement on molybdenite which are associated with cassiterite and arsenopyrite shown that the mineralization age is 141.0±1.0 Ma, and the diagenetic relationship is most closely related.The major and trace elements also shown that fine-granite with high silica and alkali characteristics and was a highly fractionated I-type granitoids and providing a huge amount of ore-forming substances and heat source.Based on the diagenetic age and the mineralization age and the major and trace elements analysis, the paper preliminary account that the mineralization geological body were most likely the early cretaceous fine-grained granite.