JultikaUniversity of Oulu repository

Pyhäsalmi mine is located in central Finland, at the eastern side of the Pyhäjärvi lake. The Pyhäsalmi deposit is polymetallic Zn-Cu VMS ore body with total reserve, mined and yet to be mined, of 58.3 Mt @ Cu 0.9 %, Zn 2.4 %, S 37.8 %, Au 0.4 g/t and Ag 14 g/t. At the end of 2013, 51 Mt of ore has been mined. The mine will be in operation until August of 2019. The Pyhäsalmi deposit is hosted in a felsic-dominated bimodal Proterozoic succession. Local hydrothermal alteration is composed of sericite-quartz alteration, and intensifies when it is in close proximity with the upper ore body. The deep ore body is thrusted into unaltered metamorphosed hangingwall volcanic rock, thus separated from the alteration zone. The Pyhäsalmi district and deposit has been subjected to four different tectonic phases (D1–D4) and intrusions accompanied by them. These tectonic processes have thrusted the deposit in upright position from the original position. Basic theory of VMS formation processes can be used for modeling Pyhäsalmi deposit formation process, which in turn can benefit massive sulfide exploration.