Kinematics of the Andean sinistral wrenching along the Fagnano - Magallanes Fault Zone (Argentina-Chile Fueguian Foothills).

ROSSELLO, E.A

Barcelona, España

Simposio; 6th International Symposium on Andean Geodynamics; 2005

6th International Symposium on Andean Geodynamics

In the Fueguian Cordillera, as wells as in its oriental continuation, the Burdwood Bank, the strike faulting prevails relative to the Patagonian segment of the Andean Cordillera where the crustal thickening dominates over wrenching (Fig. 1).  The Fagnano-Magallanes Fault Zone (FFM) trends E-W along the northern foothills of the Fueguian Cordillera, in the main island of Tierra del Fuego, Southern Patagonia (Latitude 54° 32´ S). The FFM is the western trace of the main left-lateral transcurrent deformation between the continental Southamerican plate and the oceanic Scotia plate. The kinematics reflects a thrusting combination and wrenching and is consistent with the information provided by the mayor scale structures. The absence of subduction on the southern wrenching margin (between the Scotia and South American plates) determines the lack of a related magmatic activity and it allows considering it as a passive margin. This way, the passage from the continental South America to the oceanic Scotia Plates, during the Cretaceous, was preferentially transitional (passive Atlantic type) being its different mechanical competence one of the substantial causes of wrenching control and the deformation toward the continental compartment that took place later.