赣南雷公嶂钼矿床辉钼矿Re-Os年龄及其地质意义

雷公嶂钼矿床是赣南地区新发现的一座具中型钼矿找矿前景的独立钼矿床,成矿特征明显区别于赣南已发现的与钨多金属共(伴)生的钼矿床。为确定矿床成矿时代,文章利用高精度ICP-MS辉钼矿Re-Os同位素测年技术,首次获得了雷公嶂钼矿床的辉钼矿Re-Os同位素加权平均模式年龄,为(156.3±1.0)Ma,等时线年龄为(156.9±3.6)Ma,证实了矿床成岩与成矿作用同时发生,形成于南岭地区燕山早期中晚侏罗世(165～150 Ma)。矿床中辉钼矿的w(Re)为6.104×10^-6～13.974×10^-6,平均为8.507×10^-6,结合矿床地质特征和成矿岩体主量元素及Hf同位素等证据,文章认为成矿物质来自地壳,没有地幔物质加入。结合赣南地区成岩与成矿年代学资料,文章认为区内钨钼多金属矿床形成于华南中生代岩石圈大规模伸展-减薄的地球动力学背景。

Re-Os dating of molybdenites from Leigongzhang molybdenum deposit of southern Jiangxi Province and its geological significance

The Leigongzhang molybdenum deposit is a newly discovered independent molybdenum deposit in the southern part of Jiangxi Province, with a medium-sized molybdenum resources. Its metallogenic characteristics are clearly distinct from those of molybdenum deposits associated with tungsten that have been found in the region. In order to determine the metallogenic age of the deposit, the Re-Os isotope analysis of molybdenite in the ore-body was performed by inductively coupled plasma mass spectrometry (ICP-MS), and the Re-Os isotope weighted average model age was (156.3±1.0) Ma, and the isochron age was (156.9±3.6) Ma, confirming that the diagenesis and mineralization of the deposit occurred simultaneously during middle-late Jurassic of the early Yanshan period (165~150 Ma). The Re content of molybdenite in the deposit is 6.104×10^-6~13.974×10^-6, with an average of 8.507×10^-6. Combining the geological characteristics of the deposit and the evidence of the major elements and Hf isotope of the ore-forming granite, this paper concludes that the ore-forming material was come from the crust without the mantle material. Combining with the regional diagenetic and diagenetic data, this paper suggests that the regional tungsten-molybdenum deposits were formed in the geodynamic setting of lithospheric thinning and crustal extension in South China during the Mesozoic.