Deformation of the Baltic continental crust during Caledonide intracontinental subduction: Views from seismic reflection data

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Deep seismic profiling in Norway and Sweden provides documentation of the amount and style of deformation of the Baltic crust in response to Caledonian intracontinental subduction. The seismic data demonstrate that the preserved Caledonide allochthon in central Scandinavia is 15 to 20 km thick, considerably greater than the 2 to 5 km predicted from surface geologic data. Much of the thickness of allochthonous rocks results from imbrication of the Baltic basement within a thin-skinned-style thrust complex. Seismic data across the Skardora antiform, one of the basement windows in the central Caledonides, indicate that the window represents an antiformal stack of thrust sheets involving basement and cover rocks. These data suggest that many of the basement windows in the Scandinavian Caledonides may result from similar thrust culminations and that the basement windows do not expose autochthonous Baltic basement. Documentation of the response of the Baltic crust during intracontinental subduction provides new constraints on reconstructions of the Scandinavian Caledonides and insights into the style of deformation occurring in other collisional orogens.