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A paleomagnetic study of Permian and Triassic rocks from the Toulon‐Cuers Basin, SE France: Evidence for intra‐Pangea block rotations in the Permian
Author(s) -
Aubele K.,
Bachtadse V.,
Muttoni G.,
Ronchi A.,
Durand M.
Publication year - 2012
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2011tc003026
Subject(s) - geology , permian , paleomagnetism , apparent polar wander , paleontology , gondwana , paleozoic , red beds , polar wander , magnetic mineralogy , laurasia , terrane , early triassic , structural basin , magnetization , remanence , tectonics , physics , quantum mechanics , magnetic field
The identification of a massive shear zone separating Gondwana from Laurasia during late Palaeozoic times is one of the prerequisites for the controversial Pangea B to A transition. Here we present new paleomagnetic data from Permian and Triassic sediments and volcanic rocks from the Toulon‐Cuers basin, SE France, likely to be situated within this intra‐Pangea shear zone. A total of 150 samples from 14 sites were collected in the field; 108 samples yielded reliable paleomagnetic component directions based on stepwise thermal demagnetization up to maximum temperatures of 690°C. After removal of an initial viscous magnetic component from room temperature up to 200°C, a second component of reverse polarity, oriented to the south‐and‐up, was identified in almost all samples of Permian age. The Triassic samples behave similarly, with the notable difference that here, two polarities of magnetization are present. Positive field tests suggest the primary character of this characteristic magnetization. The latitudes of the resulting Early to Mid Permian paleopoles agree well with the corresponding segment of the apparent polar wander path (APWP) for Europe, whereas the longitudes are strung out along a small circle segment, indicating relative rotations between the sampled regions and stable Europe. The Triassic poles, instead, plot close to the Triassic segment of the European APWP and provide an upper time limit for the observed rotations. These results suggest a wrench faulting event associated with intra‐Pangea crustal instability and transformation during the Permian.