安徽庐枞矿集区沙溪斑岩型铜金矿床中硒、碲的赋存状态及富集规律研究

Occurrence states and enrichment regulation of selenium and tellurium in Shaxi porphyry copper-gold deposit in Luzong area,Anhui Province,China

硒和碲是重要的战略性关键金属,在现代工业和国防建设中有着广泛的应用。硒和碲通常很难形成独立矿床,目前全球大部分硒和碲来自斑岩型铜金矿床。长江中下游成矿带是我国东部重要的斑岩-矽卡岩型铜金矿床成矿带之一,前人虽然对成矿带内矽卡岩型矿床中伴生关键金属已开展了相关研究,但对成矿带内斑岩矿床中关键金属的赋存状态、分布和富集规律尚关注较少。本次工作以成矿带内沙溪斑岩型铜金矿床为研究对象,系统采集了矿床不同深度、不同类型的岩矿石样品,通过扫描电子显微镜、全岩化学分析、TIMA及矿物原位LA-ICP-MS微量成分测试等分析技术方法对矿床中硒和碲等关键金属开展了系统的研究。结果表明,沙溪矿床中硒和碲元素发生显著富集,与主成矿元素铜具有明显的正相关关系。估算矿床中伴生硒资源量约为1196t、碲资源量约为96.6t,其中硒达到大型规模,具有潜在利用价值。与成矿带内其他典型矽卡岩矿床(包括斑岩-矽卡岩矿床)相比,沙溪斑岩型矿床中硒和碲的含量明显偏低,这可能是深部成矿岩浆演化过程的差异导致的。矿床中有91.64%的硒、87.48%的碲是以独立矿物形式存在。沙溪矿床硒、碲与主成矿元素铜和金的富集规律一致,流体混合过程中氧逸度的变化可能是硒和碲的主要的沉淀机制。

Selenium and tellurium are important strategic key metals,which are widely used in modern industry and national defense construction.These two elements are usually difficult to form independent deposits,and currently most of selenium and tellurium in the world come from porphyry copper-gold deposits.The Middle-Lower Yangtze River Valley Metallogenic Belt is one of the important porphyry and skarn copper-gold deposit metallogenic belts in the eastern China.Previous studies have been carried out on the associated key metals in the skarn deposits in the metallogenic belt,but the occurrence,distribution and enrichment mechanism of the key metals in the porphyry deposits in the metallogenic belt have not been paid much attention.This work takes the Shaxi porphyry copper-gold deposit in the metallogenic belt as the research object to discuss these problems.By systematically collecting rock ore samples of different depths and types of the deposit,and through scanning electron microscopy,whole-rock geochemical analyses,TIMA,LA-ICP-MS trace composition test and other analytical techniques,systematic researches on its key metals including selenium and tellurium were carried out in this paper.The results show that a significant enrichment of selenium and tellurium have occurred in the deposit.There is an obvious positive correlation of these two elements with the main ore-forming element copper.The estimated reserves of associated selenium and tellurium metals in the deposit are about 1196 and 96.6 tons respectively,of which the selenium reserve reaches a large scale with some potential use.Compared with other typical porphyry-skarn deposits in the metallogenic belt,the contents of Se and Te in Shaxi porphyry deposits are significantly lower,which may be caused by the differences in the evolution process of deep metallogenic magmas.In this deposit,over 91.64%selenium and 87.48%tellurium exist as independent minerals.The enrichment rules of selenium and tellurium in copper-gold ore bodies in Shaxi deposit are consistent with the main ore-forming elements copper and gold.The change of oxygen fugacity during fluid mixing may be the main precipitation mechanism of the selenium and tellurium.