El vulcanismo del Terciario Inferior y Medio en los Andes Norpatagónicos (40- 42 30'S). Origen de los magmas y su relación con variaciones en la oblicuidad de la zona de subducción

KAY, S.M.; RAPELA, C.W.

Tucuman

Simposio; International Symposium on Andean Volcanism; 1987

Asociación Geológica Argentina

The evolution of Paleocene to Oligocene volcanic rocks in the Patagonian Andes (40-42º30’S) can be related through their major and trace element chemistry to changes in plate interactions. Geochemically, these rocks form a group distinct from both the modern Patagonian arc and the plateau basaltic series. The relatively ocean-like character of the Eocene volcanic rocks correlates in time with oblique convergence of the Farallon Plate. The even-more oceanic character of the Oligocene lavas approximately correlates with the transition from oblique to normal convergence and the peak of alkaline volcanic activity in the back-arc region.