The Lherz spinel lherzolite: refertilized rather than pristine mantle

Le Roux, V., Bodinier, J.-L., Tommasi, A., Alard, O., Dautria, J.-M., Vauchez, A. and Riches, A.J.V. (2007) The Lherz spinel lherzolite: refertilized rather than pristine mantle. Earth and Planetary Science Letters, 259(3-4), pp. 599-612. (doi: 10.1016/j.epsl.2007.05.026)

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Abstract

Differentiation of the Earth's mantle and formation of continental and oceanic crust occur principally through partial melting and extraction of basaltic melt. Among the mantle rocks occurring at the Earth's surface, as tectonically-emplaced massifs, abyssal peridotites or xenoliths, the harzburgites (< 5% clinopyroxene) are widely considered as refractory mantle residues left after extraction of a basaltic component. In contrast, the most fertile lherzolites (15% clinopyroxene) are generally regarded as pristine mantle, only weakly affected by partial melting. In this paper we present new convergent structural and geochemical data from the Lherz massif, the type-locality of lherzolite, indicating that the lherzolites from Lherz do not represent pristine mantle. Detailed structural mapping clearly shows that the lherzolites are secondary rocks formed at the expense of the harzburgites. Variations of major, minor and trace elements through the harzburgite–lherzolite contacts indicate that the lherzolites were formed through a refertilization process involving interaction of refractory, lithospheric mantle with upwelling asthenospheric partial melts. Combined with previously published indications of refertilization in orogenic peridotites, our new observations in Lherz suggest that most lherzolite massifs represent secondary (refertilized) rather than pristine mantle. Together with geochemical data on mantle xenoliths, this indicates that melt transport and melt-rock reaction play a key role on the rejuvenation and erosion of the lithospheric mantle.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Riches, Dr Amy
Authors: Le Roux, V., Bodinier, J.-L., Tommasi, A., Alard, O., Dautria, J.-M., Vauchez, A., and Riches, A.J.V.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
Journal Name:Earth and Planetary Science Letters
Publisher:Elsevier
ISSN:0012-821X
ISSN (Online):1385-013X
Published Online:24 May 2007

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