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Experimental study on a basanite from the McMurdo Volcanic Group, Antarctica: inference on its mantle source

Published online by Cambridge University Press:  06 May 2004

Andrea Orlando
Affiliation:
C.N.R., Centro di Studio per la Minerogenesi e la Geochimica Applicata, Via G. La Pira, 4, I-50121 Firenze, Italy
Sandro Conticelli
Affiliation:
C.N.R., Centro di Studio per la Minerogenesi e la Geochimica Applicata, Via G. La Pira, 4, I-50121 Firenze, Italy Università degli Studi della Basilicata, Via N. Sauro, 85, I-85100, Potenza, Italy
Pietro Armienti
Affiliation:
Dipartimento di Scienze della Terra, Università degli Studi di Pisa, Via S. Maria 53, I-56100 Pisa, Italy
Daniele Borrini
Affiliation:
C.N.R., Centro di Studio per la Minerogenesi e la Geochimica Applicata, Via G. La Pira, 4, I-50121 Firenze, Italy Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira, 4, I-50121 Firenze, Italy

Abstract

Experiments to reconstruct the liquidus curve and establish the phase relationships of a basanite (Mg# = 72) from the McMurdo Volcanic Group, (thought to represent a nearly primary magma) used 1.0– 3.0 GPa and 1175–1550°C. The results suggest that this basanite could be generated by partial melting either of a spinel Iherzolite (at P = 1.5–2.0 GPa and T = 1390–1490°C) or of a garnet pyroxenite (at P > 3.0 GPa and T > 1550°C) source. Several lines of petrological and geochemical evidence support the latter hypothesis. Moreover, experimental results indicate the presence of mica in the source if it is assumed that the magma lost some water during its ascent to the surface. This is supported by the presence of mica and amphibole-bearing mantle xenoliths hosted in the most primitive volcanic rocks of the McMurdo Volcanic Group. These results and observations suggest that the source of magmas underwent metasomatism prior to partial melting.

Type
Papers—Earth Sciences and Glaciology
Copyright
© Antarctic Science Ltd 2000

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