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Department for General and Applied Geology, University of Munich, Luisenstrasse 37 80333 München, Germany
The transitional position of the South Patagonian (Deseado) Massif between the subduction-related compressional Andean stress field and the rift-related extensional Atlantic stress field since the Early Jurassic is documented by several deformation events. Analysis of enhanced ERS-1-SAR-images and Landsat-Thematic Mapper images compared with field data led to the establishment of several deformation events. Brittle shear tectonics dominated in the Late Jurassic and Early Cretaceous with a maximum principal stress changing from 15° counterclockwise through 350° to 310°. The interaction of strike-slip faults with the changing direction of maximum principle stress produced transtensive and transpressive structures. Extensional deformation at the Hauterivian-Barremian boundary can be inferred from the opening of the South Atlantic when shearing ended. Compressional deformation from the Albian on must be related to the first stages of the Andean Orogeny. The uplift of the massif reactivated pre-existing structures and produced tension faults which controlled the extrusion of the first intracontinental basalts.
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