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GEOREF RECORD

First field-scale occurrence of Si-Al-Na-rich low-degree partial melts from the upper mantle

C. Pin, J. L. Paquette, P. Monchoux and T. Hammouda
First field-scale occurrence of Si-Al-Na-rich low-degree partial melts from the upper mantle
Geology (Boulder) (May 2001) 29 (5): 451-454

Abstract

Felsic dikes intruding an orogenic lherzolite body from the North Pyrenean zone (France) show great compositional similarities to some of the Si-Al-Na(K)-rich glasses found as microscopic inclusions in peridotite xenoliths. As shown by Sr-Nd isotopes, these silicic magmas originated from a mantle reservoir that was moderately depleted on a time- integrated basis. Their Si-Al-Na-rich bulk compositions match closely those predicted by experimental studies relevant to near-solidus melting of mantle peridotite. Specifically, the dikes are closely similar to low-degree melts from sodic harzburgite. On this basis, an olivine-orthopyroxene source that had been metasomatized by addition of sodic-carbonatite melts is inferred, as also suggested by peculiar trace element features (extreme fractionation of the light rare earth elements, high Nb contents). This new occurrence lends support to the existence of high-silica liquids in the mantle and provides evidence for their efficient extraction to form relatively large batches.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 29
Serial Issue: 5
Title: First field-scale occurrence of Si-Al-Na-rich low-degree partial melts from the upper mantle
Affiliation: Universite Blaise Pascal, Departement de Geologie, Clermont-Ferrand, France
Pages: 451-454
Published: 200105
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 26
Accession Number: 2001-038575
Categories: Isotope geochemistryIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Secondary Affiliation: Universite Paul Sabatier, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200112
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