GONDWANAN MAGMATISM WITH ADAKITE-LIKE SIGNATURE LINKED TO CU (MO)-PORPHYRY DEPOSITS FROM THE SAN RAFAEL MASSIF, MENDOZA PROVINCE, ARGENTINA

GÓMEZ ANABEL L.R.; RUBINSTEIN NORA A.; VALENCIA VICTOR A.

CHEMIE DER ERDE

ELSEVIER GMBH, URBAN & FISCHER VERLAG

Lugar: ALEMANIA; Año: 2015 vol. 75 p. 89 - 104

0009-2819

tThe gondwanan magmatism in the San Rafael Massif, known as Choiyoi Magmatic Cycle, was emplacedduring the inception of a magmatic arc setting during the early Permian. Two different sections can bedifferentiated in this volcanic sequence. The lower section (∼281 up to ∼265 Ma) consisting of andesitesand dacitic to low-silica rhyolitic ignimbrites has geochemical characteristics that indicate a subductionzone setting. The upper section (∼265 up to ∼252 Ma) composed of rhyolitic ignimbrites and lava flows,dacitic to rhyolitic subvolcanics and alkalic basaltic andesites has geochemical characteristics transitionalbetween subduction and continental intraplate settings. Several Cu?(Mo) porphyry deposits are geneti-cally linked to the lower section (Infiernillo, San Pedro and La Chilca-Zanjón del Buitre). In this paper, wediscussed the petrogenesis of the magmatism linked to the porphyry deposits from the San Rafael Massif.The petrogenetic analysis suggests that the lower section was produced in a thickened crust resultingin an adakite-like signature magmatism. The U/Pb LA-ICP-MS age of magmatic zircons from an intru-sive associated to the San Pedro porphyry (263.1 ± 4.2 Ma) allowed confirming that the emplacementof Cu?Mo porphyry deposits in the San Rafael Massif occurred during the change in the geodynamicalconditions from a transpressive to a transtensive tectonic regime.