Two million years of evolution of the southern central andes retroarc, Payenia Volcanic Province, Argentina, from the study of the Cerro Nevado Volcanic Complex

PALLARES, CARLOS; SARDA, PHILIPPE; QUIDELLEUR, XAVIER; ANTOINE, CLÉMENTINE; TCHILINGUIRIAN, PABLO; WINOCUR, DIEGO; FOLGUERA, ANDRÉS; MAURY, RENÉ C.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2023 vol. 123

0895-9811

New K–Ar ages, major and trace element analyses, and Sr and Nd isotopic data for the Cerro Nevado VolcanicComplex (CNVC) coupled with those previously published allow us to better document the hot thermal anomalywhich affected the upper mantle beneath the Andean back-arc Payenia Volcanic Province and generated alkalinemagmatism. These data, along with previously published ones from this and neighbor volcanic centers, suggestthat this anomaly stagnated there, during at least the last 2 million years. Geochemical features from the CNVCbasaltic magmas indicate that they were sourced within an OIB-type mantle with an EMI signature, similar tothat underlying the neighboring Auca Mahuida Shield Volcano to the south, and attributed to the rise of a mantlethermal anomaly. We identify at least five events of partial melting and seven eruptive phases from 1.88 to 0.75Ma. Continental crust contamination in the San Rafael Block crustal basement occurred coupled with fractionalcrystallization processes, probably in magma chambers and across several cycles, producing the trachybasaltic,trachyandesitic and trachytic magmas of the Cerro Nevado volcanic cone (1.34–1.22 Ma).