Geochemistry of the Cenozoic plateau lavas from the Pali Aike are (52˚S), southern Patagonia, South America

Abstract

Geochemical and Sr-Nd-Pb isotopic analyses of late Miocene to Quaternary plateau lavas from the Pali Aike Volcanic Field (PAVF) and Morro Chico Volcano (MCV) (52°S) were undertaken to constrain the melting processes and mantle sources that contributed to magma generation and the geodynamic evolution of southernmost Patagonia, South America.The PAVF and MCV lavas from the southernmost part of Patagonia have lower 87Sr/86Sr and higher 143Nd/144Nd and 206Pb/204Pb ratios, relative to most of the southern Patagonian lavas erupted north of 49.5°S, pointing to a HIMU-like signature. An isotopically depleted and HIMU-like asthenospheric domain may have been the main source of magmas in the southernmost part of Patagonia, suggesting the presence of a major discontinuity in the isotopic composition of the asthenosphere in southern Patagonia.that contributed to magma generation and the geodynamic evolution of southernmost Patagonia, South America.The PAVF and MCV lavas from the southernmost part of Patagonia have lower 87Sr/86Sr and higher 143Nd/144Nd and 206Pb/204Pb ratios, relative to most of the southern Patagonian lavas erupted north of 49.5°S, pointing to a HIMU-like signature. An isotopically depleted and HIMU-like asthenospheric domain may have been the main source of magmas in the southernmost part of Patagonia, suggesting the presence of a major discontinuity in the isotopic composition of the asthenosphere in southern Patagonia.