Abstract

The Cantabria-Asturias arc of southwestern Europe is a highly curved Variscan belt that formed along the ancient plate boundary between Gondwana and Laurussia during the assembly of Pangea. New paleomagnetic data from 59 sites in the southern limb of the arc were combined with previously published data from 109 sites to determine the evolution of the arc. A previously unrecognized postrotation magnetization is found in the southern limb, refuting earlier models of arc formation that concluded secondary rotation of only 50% of present-day arc curvature. The new data show that the arc underwent true (100%) oroclinal bending of an originally linear belt in a two-stage tectonic history. This history represents two regional compression phases: (1) east-west in the late Carboniferous (Pennsylvanian) and (2) north-south in the Permian (both in present-day coordinates). The north-south compression phase coincides with the northward movement of Gondwana and its final collision with Laurussia. This tectonic scenario argues against an indentor scenario, and does not support a 3500 km dextral megashear proposed in earlier reconstructions.

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