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

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 8.76Mt. 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.