瑞典正科格鲁万铅锌矿床地质特征及成矿模式

Geological characteristics and metallogenic model of the Zinkgruvan lead-zinc deposit, Sweden

正科格鲁万铅锌矿位于瑞典中南部贝里斯拉根(Bergslagen)矿集区的最南端,该矿有超过150年的采矿历史,矿产储量巨大,达8.76Mt。北北东向断裂系将矿床分成两部分:1东侧的尼格尔矿段,Pb、Zn和Au品位分别为1.5%、10%和45g/t;2西侧的克纳拉(Knalla)矿段,Pb、Zn和Ag品位分别为5.5%、6%和100g/t。矿体呈层状产出,与围岩界线清晰,围岩普遍发生钾长石化,局部有硅化、电气石化、绢云母化等。根据锆石U-Pb和Sm-Nd同位素测年,其成矿年龄在1.9Ga左右,形成于古元古代。稳定同位素地球化学特征表明,成矿物质为壳幔混合来源。该矿的成矿构造环境可能为克拉通边缘坳陷盆地或弧后裂谷环境,而矿床成因存在多种认识,还有待进一步研究。正科格鲁万铅锌矿与中国青城子铅锌矿具有一定的相似性,该矿的研究对青城子地区向深部与外围找矿具有指导意义。正科格鲁万矿山采矿技术和设备先进,现代化程度高,值得中国矿山企业引进学习。贝里斯拉根地区具有很好的资源前景。

The Zinkgruvan lead-zinc deposit is located in the southernmost Bergslagen ore district, central and southern Sweden. Its mining history has lasted for over 150 years. The mineral reserves are rich, reaching 8.76 Mt. The deposit is divided into two parts by NNE-trending fault system： the eastern Nygruvan ore block and the western Knalla ore block. Lead, zinc and silver grades are 1.5%,10% and 45g/t in Nygruvan, and are 5.5%, 6% and 100g/t in Knalla. Orebodies are in layered form, and the boundary between the orebody and the country rock is distinct. Country rock has experienced K-feldspathization, with local silicification, tourmalinization,sericitization, and some other alterations. Zircon U-Pb and Sm-Nd isotopic dating yielded the mineralization age of around 1.9Ga,suggesting early Proterozoic. Stable isotope geochemical analysis shows that ore-forming metals were derived from crust-mantle mixing. The metallogentic tectonic environment might have been cratonic marginal depressional basin or back-arc rift. However, the ore genesis remains to be further studied. The deposit is similar to the Qingchengzi lead-zinc deposit in many aspects, such as the attitude of orebody, ore-controlling structure, magmatic activity, ore-forming material source, and metallogeny. In addition, Zinkgruvan can provide guiding significance for the Qingchengzi area＇s deep and peripheral prospecting. The Zinkgruvan mine has advanced and highly modernized mining technology and equipment, and these advantages deserve introduction and study in favor of China＇s national mining enterprises. The Bergslagen area has good prospects for resources.