DEXTRAL TRANSCURRENT MOVEMENTS ALONG THE NORTHERN BOUNDARY OF PATAGONIA, SUGGESTED BY PALEOMAGNETIC DATA.

The paleomagnetic pole position of the Late Permian Choiyoi Formation, exposed at the Cerro Chachil (39.1°8,70.5°W), in the Southern Andes, Argentina, is not concordant with the position of the coeval paleomagnetic poles from Cratonic South America. This suggests an "in situ" clockwise rotation of the sampling area of about 80° around a vertical axis. It is proposed that this crustal block rotation is related to the dextral transpressive movements that generated the Neuquen Dorsal, during the Jurassic and/or Cretaceous. It is also suggested that the block rotation, the Neuquen Dorsal and its eastward extension, the Rio Negro Fault, could have been generated by a dextral displacement of Patagonia respect to South America in the Jurassic and/or Cretaceous.