http://www.cnr.it/ontology/cnr/individuo/prodotto/ID29121

Growth of early continental crust controlled by melting of amphibolite in subduction zones. (Articolo in rivista)

Type

Label

Growth of early continental crust controlled by melting of amphibolite in subduction zones. (Articolo in rivista) (literal)

Anno

Alternative label

FOLEY S., TIEPOLO M., VANNUCCI R. (2002)
Growth of early continental crust controlled by melting of amphibolite in subduction zones.
in Nature (Lond.)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Pagina inizio

Pagina fine

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#altreInformazioni

This work, published in one of the scientific journals with the highest impact factor and with the highest diffusion, represent an important contribution in understanding the evolution of our planet. It focuses on the mechanism of formation of the continental crust in the Archean time and demonstrate that it formed as a consequence of the partial melting of the subducted oceanic lithosphere in the amphibolite facies and not in eclogite facies as commonly supposed. It also exclude the partial melting of the lower crust as an alternative model. These conclusions has been possible thanks to the application of new results on trace element partitioning between amphibole and melt to natural amphiboles. It has been demonstrated that only Fe-rich amphibole, from the subducted slab represent a suitable residual phase to achieve Nb/Ta ratios lower than chondrites as shown by the early continental crust. (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

Rivista

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#note

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto

It is generally accepted that the first continental crust formed by melting of either eclogite or amphibolite, either at subduction zones or on the underside of thick oceanic crust. The compositions of early crustal gneisses and experimental studies support these interpretations, but our understanding of trace element partitioning could not distinguish between them up to now. Here, we show a clear contrast in trace element ratios of melts derived from amphibolites and those from eclogites. Partial melting of low-Mg# (<70) amphibolite can explain low Nb/Ta and high Zr/Sm in melts, as required for the early continental crust, whereas melting of eclogite cannot. This indicates formation of the earliest continental crust by melting of amphibolites in subduction zones and not by melting of eclogite nor Mg-rich amphibolites (Mg#>80) in the lower part of thick ocean crust. The low Nb/Ta seen in subduction zone igneous rocks of all ages is compelling geochemical evidence that melting of rutile-eclogite has never been a volumetrically important process. (literal)

Note

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

S. Foley a), M. Tiepolo b), R. Vannucci b,c). a) Institut für Geowissenschaften, Universität Mainz, 55099 Mainz, Germany, b) C.N.R.-IGG-Sezione di Pavia, via Ferrata 1, I-27100 Pavia, c) Dipartimento di Scienze della Terra, Università di Pavia, via Ferrata 1, I-27100 Pavia. (literal)

Titolo

Growth of early continental crust controlled by melting of amphibolite in subduction zones. (literal)

Abstract

It is generally accepted that the first continental crust formed by melting of either eclogite or amphibolite, either at subduction zones or on the underside of thick oceanic crust. The compositions of early crustal gneisses and experimental studies support these interpretations, but our understanding of trace element partitioning could not distinguish between them up to now. Here, we show a clear contrast in trace element ratios of melts derived from amphibolites and those from eclogites. Partial melting of low-Mg# (<70) amphibolite can explain low Nb/Ta and high Zr/Sm in melts, as required for the early continental crust, whereas melting of eclogite cannot. This indicates formation of the earliest continental crust by melting of amphibolites in subduction zones and not by melting of eclogite nor Mg-rich amphibolites (Mg#>80) in the lower part of thick ocean crust. The low Nb/Ta seen in subduction zone igneous rocks of all ages is compelling geochemical evidence that melting of rutile-eclogite has never been a volumetrically important process. (literal)

Prodotto di