ANDEAN OBLIQUE MEGASHEAR ZONES: PALEOMAGNETISM CONTRIBUTION

Paleomagnetic analysis carried out during the past two decades have delineated the partition of the andean chain into two sectors, North and South of the Arica code (18°S), based on the presence of counterclockwise and clockwise rotations, respectively.

Tectonic fabric analysis focused on the 22°S to 33°S argentine segment of the Andes of South America (Central Andes) show a recurrent pattern of lineaments which indicate lateral motions. Based on both paleomagnetic data and strain fabric analysis two sets of conjugate megashear zones could be defined: NNE (dextral transpression) and NNW (sinistral transpression) ones, indicating that counterclockwise rotations are also linked to Central Andean history.

Deformation within these megashear zones is not homogeneous as a whole as could be seen in the Vinchina area (28°44'S, 68°W), where rotation is constrained to localized bands.