CARACTERIZACIÓN PETROGRÁFICA Y GEOQUÍMICA DEL VOLCÁN CUEROS DE PURULLA, PUNA AUSTRAL

ARNOSIO M.; BARDELLI L.; BAEZ W.; BERTEA, E.; SOMMER C.

Congreso; XIII Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogénesis; 2019

The Southern Puna is characterized by the presence of Miocene to Holocenesilicic volcanism. One of the representatives of this activity is the Cueros de Purulla Volcano(CDPV), located 20 km NW of the Cerro Blanco Volcanic Complex (CBVC) on the easternflank of the Sierra de Calalaste. The CDPV was poorly studied in the past, reason why wehere present a petrographic and geochemical characterization of the volcano and acomparison with other rhyolitic volcanic deposits of the Andean back-arc area. The CDPVproducts are slightly peraluminous crystal-poor rhyolitic rocks (lava domes, fall deposits)with cryptocrystalline-vitreous matrix which belong to the high-K calc-alkaline series. Thesedeposits display geochemical affinities with most of the Miocene to Pleistocene rhyolitesoutcropping in the Southern Puna (e.g. high Rb and Ba contents) and some differences withthe Cerro Blanco deposits and other rhyolitic centers from the northern Puna. We infer thatthe CDPV rhyolites may represent the periodical extraction of differentiated melts from afairly homogeneous crystal-mush zone beneath the Southern Puna. This hypothesis is alsosupported by geophysical evidence (teleseismic tomography).