Central Andean magmatism can be constrained by three ubiquitous end-members

Year:

2016

Type of Publication:

Article

Authors:

Blum-Oeste, Magdalena; Wörner, Gerhard

Journal:

Terra Nova

Volume:

28

Number:

6

Pages:

434-440

ISSN:

1365-3121

BibTex:

@article{TER:TER12237, author = "Magdalena Blum-Oeste and Gerhard W{\"o}rner", abstract = "The geochemical character of primary magmas and the nature of crustal melts remain poorly constrained at the active continental margin of the Central Andes, where the crustal thickness is {\&}gt;70 km. We identify three end-members and constrain their full major and trace element compositions by polytopic vector analysis (PVA). The end-members include two mafic parent magmas: (1) a slightly evolved calcalkaline basaltic andesite derived from the fluid-fluxed mantle wedge that is typical of the Andes in general and (2) a strongly LREE-enriched basalt akin in its trace element pattern to back-arc shoshonites. (3) The third end-member is a variably HREE-depleted rhyodacite representing partial melts of lower to middle crustal lithologies. We propose that these end-members are ubiquitous and typical of such thick-crust settings, and can explain – in highly variable mixing proportions – the entire compositional range of Central Andean magmatism.", doi = "10.1111/ter.12237", issn = "1365-3121", journal = "Terra Nova", number = "6", pages = "434--440", title = "{C}entral {A}ndean magmatism can be constrained by three ubiquitous end-members", url = "http://dx.doi.org/10.1111/ter.12237", volume = "28", year = "2016", }

Abstract:

The geochemical character of primary magmas and the nature of crustal melts remain poorly constrained at the active continental margin of the Central Andes, where the crustal thickness is >70 km. We identify three end-members and constrain their full major and trace element compositions by polytopic vector analysis (PVA). The end-members include two mafic parent magmas: (1) a slightly evolved calcalkaline basaltic andesite derived from the fluid-fluxed mantle wedge that is typical of the Andes in general and (2) a strongly LREE-enriched basalt akin in its trace element pattern to back-arc shoshonites. (3) The third end-member is a variably HREE-depleted rhyodacite representing partial melts of lower to middle crustal lithologies. We propose that these end-members are ubiquitous and typical of such thick-crust settings, and can explain – in highly variable mixing proportions – the entire compositional range of Central Andean magmatism.