A refraction profile in the Caledonian Front of the Tåsjön area, north central Sweden

Abstract

A seismic refraction profile about 34 km long was investigated in the Tåsjön area of north central Sweden. The profile was orientated nearly perpendicular to the Caledonian Front. Very clear first arrivals were recorded from the sedimentary layers, as well as from the underlying granitic basement. From some of the shot points, transverse waves were recorded, as well as surface waves. The interpretation has been made, using travel-time analysis of the first P-wave arrivals, as well as S-wave arrivals. Relatively high velocities, 4.4–5.4 km/s were recorded from the sedimentary cover. A normal upper-crust velocity, about 6.0 km/s, was recorded from the basement. The thickness of the sedimentary cover increases from about 0.34 km in the eastern part of the profile to about 1.3 km in the western part of the profile. The granitic basement rises from 0.94 km below sea level in the western part of the Caledonian Front to 0.09 km below sea level in the central part of the Front.