Foundering-driven lithospheric melting: The source of central Andean mafi c lavas on the Puna Plateau (22°S–27°S)

Abstract

Investigations of lithospheric foundering and related magmatism have long focused on the central Andes, where there are postulated links between the eruption of mantle-derived lavas and periodic loss of the lower lithosphere. Whole-rock ele-mental and Nd-Sr-Pb isotopic results from a suite of late Miocene–Quaternary mafi c lavas erupted onto the Puna Plateau clarify the relationship between this hypothe-sized process and lava composition. Zinc and Fe provide a critical perspective because they are partitioned differently during the melting of asthenospheric and lithospheric mantle. All Puna lavas have Zn/FeT (×104) values>13, which requires clinopyroxene and perhaps garnet to be the dominant phase(s) in the melt source; this precludes a melt source of typical mantle asthenosphere. This result is contrary to classic models of delamination magmatism that suggest asthenospheric peridotite melts to gener-ate these lavas. Pyroxenite (±garnet)–bearing lithospheric materials in the central Andes are likely common and heterogeneous in age, volatile content, and mineralogi-cal composition, and if they are the melt source, this can explain the diversity in th

Similar works

Full text

thumbnail-image
oai:CiteSeerX.psu:10.1.1.908.5662Last time updated on 11/1/2017

This paper was published in CiteSeerX.

Having an issue?

Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will take corresponding actions after reviewing your request.