TERTIARY VOLCANISM FROM IGLESIA VALLEY BASIN, SAN JUAN PROVINCE, ARGENTINA

POMA, STELLA; RAMOS, ADRIANA; LITVAK, VANESA D.; QUENARDELLE, SONIA; MAISONNAVE, BEATRIZ

Córdoba

Congreso; 19° Congreso Geológico Argentino; 2014

Universidad Nacional de Córdoba

The Iglesia Valley Basin is part of the Iglesia-Calingasta-Uspallata depression, a NS regional intermountain structure that stretches from 29º30? LS to 32º30? LS, along 350 kilometers. At these latitudes and simultaneously with the Miocene volcanic activity at the orogenic front, an eruptive sequence was accumulated at the eastern extreme of the arc, so this magmatism can be considered as in a backarc position. They are dacitic to andesitic well preserved sequence of pyroclastic flows with surge and fallout deposits, associated with lava flows and small subvolcanic centers hosted in Paleozoic rocks, whose exposure is favored by recent fluvial erosion. Petrologic and geochemical studies of these volcanics along with the new 40Ar/39Ar and K/Ar data ages contribute to elucidate peculiarities of the magmatic signature in arc and back-arc rocks, as well as its eastward projection in the present Iglesia Valley Basin.