Counterclockwise rotation of the western Alps since the Oligocene: New insights from paleomagnetic data
作者： M. Collombet , J. C. Thomas , A. Chauvin , P. Tricart , J. P. Bouillin
DOI: 10.1029/2001TC901016
关键词:
摘要: [1] A paleomagnetic study of Penninic units in the southern part Alpine arc has been carried out. More than 200 samples (23 sites) were collected Brianconnais Ammonitico rosso limestones high Ubaye valley and Ligurian Alps. A characteristic component magnetization reverse polarity was isolated on most sites. This does not pass fold test is interpreted as a Tertiary overprint related to metamorphism. Mean directions geographic coordinates are D = 121°, I −52°, α95 11°, 72°, −48°, 15° for Liguria localities, respectively, indicating large counterclockwise rotations about vertical axis 68° 117° relative stable Europe. These rotations, agreement with previous conducted Briancon area, together other data from western Alps, show that internal Alps suffered but nonhomogeneous rotation since Oligocene. The combination earlier separately proposed processes: Adriatic plate accounts 25° rotation, remaining southward gradient would be left-lateral shear accommodating displacement between Adria Europe at border Furthermore, extrusion south Simplon fault zone may account up 10° rotation. Rotations appear therefore major process deformation
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