Magnetotellurics in southwestern Sweden: Evidence for electrical anisotropy in the lower crust?

Magnetotelluric data from measurements conducted on the southwestern part of the Baltic Shield are analyzed with respect to crustal and upper mantle structures. The interpretations have been done using ordinary two‐dimensional and transverse anisotropic layered models in which distortions of the impedance tensors due to near‐surface electrical structures are included in the interpretation procedures. The anisotropic model is able to explain the gross features of the data, whereas the two‐dimensional model only displays features observed at long periods. The two main results from the study with anisotropic models are the interpretation of a possible transverse anisotropic lower crust and a depth to the uppermost conductive layer within the mantle of more than 200 km. The minimum depth to the conductive mantle layer is found from a most squares analysis.