Adakite-like signatures of Middle-Late Miocene intrusions at the Altar porphyry Cu-(Mo-Au) deposit (31º 29' S, 70º 28´ W) in the Andean Main Cordillera of San Juan, Argentina.

MAYDAGÁN LAURA; FRANCHINI, MARTA; CHIARADIA, MASSIMO; MAS, GRACIELA; IMPICCINI, AGNES

Keystone

Congreso; SEG 2010 Conference. The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration and New Discoveries; 2010

Society of Economic Geologists

Adakite-like signatures have been recognized in the Middle-Late Miocene porphyritic intrusions of the Altar porphyry Cu-(Au-Mo) prospect (31º 29´ S, 70º 28´ W) located within the southern portion of the Andean flat-slab segment (28 33ºS), Argentina. We suggest that these features are derived from magmas that equilibrated under high pressure conditions, in a MASH-like zone, with an amphibole- to garnet-bearing residual mineralogy. The ~10 Ma age of these rocks coincides with the early stages of shallowing of the slab beneath the central Flat Slab segment and with the arrival of the Juan Fernández Ridge to this region, which are both processes held responsible for promoting crustal thickening and compression on the overriding plate. This increased compression in the continental crust might be related to the increase in depth of magma evolution of the Middle-Late Miocene Altar rocks.