CHANGES IN SUBDUCTION DIRECTION AND RIDGE COLLISION AGAINST A CURVED OROGEN: THE CASE OF THE SOUTHERNMOST ANDES

GHIGLIONE, M.C.; RAMOS, V.A.

Mendoza

Congreso; Backbone of the Americas, GSA Mendoza; 2006

A recently updated chronology of deformation in the southernmost Andes is combined with plate tectonic reconstructions to reveal the connection between deformational events and ridge collision in combination with changes in subduction speed and direction. Late Cretaceous-Tertiary evolution of the southern tip of the Andes and its present structural conformation are explained as due to a convergent subduction system on a curved plate boundary. This configuration implies that an eastwardoriented convergence vector for the Farallon – Aluk plates resulted in an oblique subduction against the Fuegian Andes and an orthogonal subduction against the Patagonian Andes, whereas a northward convergence vector produced the inverse effect.