Abstract

D´ANNUNZIO, María C  and  RUBINSTEIN, Nora. Caracterización geoquímica de las rocas pertenecientes al Complejo Igneo Gualcamayo, Precordillera de San Juan. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.3, pp.369-377. ISSN 0004-4822.

The Gualcamayo Igneous Complex is formed by intrusives and dykes of riodacitic to andesitic composition, located in Gualcamayo Mining District, Central Precordillera of San Juan province, in the flat-slab segment of the Central Andes (28- 33 ºS). Field data, petrographic studies and geochemical analyses together with preexisting radiometric ages indicate that they are the product of a Late Miocene (~9 Ma) magmatic stage occurred in an arc tectonic setting with a normal to intermediate thickness crust (~45 km). Linked to this magmatic stage there is an important hydrothermal activity that produced mainly potassic (potassium feldspar-quartz-biotite-magnetite) and subordinate propylitic alteration probably produced by a porphyry copper system. The oxidizing character of this magmatism suggests mineralizing potential for generating porphyry copper type deposits. Moreover andesitic sills formed in a tectonic setting with a normal crust (~30 km). Field data and petrographic studies allow correlating these andesites with the andesitic facies of the Lower Miocene (17-18 Ma) del Aspero Group.

Keywords : Petrography; Hydrothermal alteration; Geochemistry; Miocene magmatism; Central Precordillera.

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