Velocity structure of the Earth’s crust and upper mantle in the Pechenga ore region and adjacent areas in the northwestern part of the Lapland-Kola orogen by the receiver function technique

Abstract

The article presents a study of the Earth’s crust and upper mantle in the Pechenga ore region, as well as areas adjacent to it in the northwestern part of the Kola region. Applying the receiver function technique to data acquired by three broadband seismic stations, we obtained one-dimensional seismic velocity distribution models to a depth of 300 km. The stations are located in the northern parts of Finland and Norway, as well as in the Pechenga region of the Russian Federation. Despite the stations being in relatively close proximity (within 100 km of each other), the velocity models turned out to be significantly different, which indicates structural discontinuity within the lithosphere. Thus, Finland station data set revealed a gradient crust-mantle transition, which is not present in the other two models. At depths of about 150 km, a low-velocity zone was discovered, associated with mid-lithospheric discontinuity, which was not found beneath the Pechenga ore region. Furthermore, the crustal structure of the Pechenga region has an anomalously high Vp/Vs ratio to a depth of about 20 km. Considering the fact that the Pechenga (Nikel) seismic station was installed in close proximity to major copper-nickel deposits, this anomaly can be interpreted as a relic of Proterozoic plume activity.

Keywords

• kola peninsula
• lapland-kola orogen
• lithosphere
• mantle
• receiver function
• ore deposits
• plume