Crustal structure of central Norway and Sweden from integrated modelling of teleseismic receiver functions and the gravity anomaly

Abstract

SUMMARY Receiver functions have been calculated from teleseismic events recorded by an array of seismometers deployed on an E-W transect between the coasts of central Norway and Sweden. Forward and inverse modelling and migration of the receiver functions yields models for the subsurface velocity structure along the profile which have the crust thickening from c. 32 km at the Norwegian coast to c. 43 km beneath the central Scandinavian mountain range and then remaining constant beneath Sweden. There is some evidence for a low-velocity layer in the upper 10 km of the crust beneath parts of Norway and western Sweden and good evidence for a high-velocity lower crust underlying much of Sweden which thins to the west beneath Norway. Inverting the seismic velocities to density results in a very good correspondence between calculated and observed gravity anomalies. The results of this study do not support the presence of a significant crustal root providing buoyant support for the mountain range. Low topography and thick crust beneath Sweden are maintained by the high-velocity, high-density lower crustal layer. The upper crustal low-velocity layer is consistent with models based on existing refraction profiling and known geology and physical properties of the crust. There is no direct correlation between properties of the crust and topography suggesting that recent epeirogenic uplift has not resulted from modification of the crust.