Skip Navigation


Journal of Petrology Advance Access originally published online on September 9, 2004
Journal of Petrology 2004 45(12):2573-2612; doi:10.1093/petrology/egh063
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
45/12/2573    most recent
egh063v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (5)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by NEUMANN, E.-R.
Right arrow Articles by O'REILLY, S. Y.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Journal of Petrology 45(12) © Oxford University Press 2004; all rights reserved

The Evolution of the Upper Mantle beneath the Canary Islands: Information from Trace Elements and Sr isotope Ratios in Minerals in Mantle Xenoliths

ELSE-RAGNHILD NEUMANN1,*, WILLIAM LINDSEY GRIFFIN2,3, NORMAN J. PEARSON2 and SUZANNE YVONNE O'REILLY2

1 PHYSICS OF GEOLOGICAL PROCESSES, UNIVERSITY OF OSLO, PO BOX 104, BLINDERN, NO-0316 OSLO, NORWAY
2 GEMOC ARC NATIONAL KEY CENTER, DEPARTMENT OF EARTH AND PLANETARY SCIENCES, MACQUARIE UNIVERSITY, SYDNEY, N.S.W. 2109, AUSTRALIA
3 CSIRO EXPLORATION AND MINING, NORTH RYDE, N.S.W. 2113, AUSTRALIA

Laser ablation microprobe data are presented for olivine, orthopyroxene and clinopyroxene in spinel harzburgite and lherzolite xenoliths from La Palma, Hierro, and Lanzarote, and new whole-rock trace-element data for xenoliths from Hierro and Lanzarote. The xenoliths show evidence of strong major, trace element and Sr isotope depletion (87Sr/86Sr ≤ 0·7027 in clinopyroxene in the most refractory harzburgites) overprinted by metasomatism. The low Sr isotope ratios are not compatible with the former suggestion of a mantle plume in the area during opening of the Atlantic Ocean. Estimates suggest that the composition of the original oceanic lithospheric mantle beneath the Canary Islands corresponds to the residues after 25–30% fractional melting of primordial mantle material; it is thus significantly more refractory than ‘normal’ mid-ocean ridge basalt (MORB) mantle. The trace element compositions and Sr isotopic ratios of the minerals least affected by metasomatization indicate that the upper mantle beneath the Canary Islands originally formed as highly refractory oceanic lithosphere during the opening of the Atlantic Ocean in the area. During the Canarian intraplate event the upper mantle was metasomatized; the metasomatic processes include cryptic metasomatism, resetting of the Sr–Nd isotopic ratios to values within the range of Canary Islands basalts, formation of minor amounts of phlogopite, and melt–wall-rock reactions. The upper mantle beneath Tenerife and La Palma is strongly metasomatized by carbonatitic or carbonaceous melts highly enriched in light rare earth elements (REE) relative to heavy REE, and depleted in Zr–Hf and Ti relative to REE. In the lithospheric mantle beneath Hierro and Lanzarote, metasomatism has been relatively weak, and appears to be caused by high-Si melts producing concave-upwards trace element patterns in clinopyroxene with weak negative Zr and Ti anomalies. Ti–Al–Fe-rich harzburgites/lherzolites, dunites, wehrlites and clinopyroxenites formed from mildly alkaline basaltic melts (similar to those that dominate the exposed parts of the islands), and appear to be mainly restricted to magma conduits; the alkali basalt melts have caused only local metasomatism in the mantle wall-rocks of such conduits. The various metasomatic fluids formed as the results of immiscible separations, melt–wall-rock reactions and chromatographic fractionation either from a CO2-rich basaltic primary melt, or, alternatively, from a basaltic and a siliceous carbonatite or carbonaceous silicate melt.

KEY WORDS: mantle xenoliths; mantle minerals; trace elements; depletion; carbonatite metasomatism

* Corresponding author. E-mail: e.r.neumann{at}geologi.uio.no


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 J PetrologyHome page
N. S. C. Simon, E.-R. Neumann, C. Bonadiman, M. Coltorti, G. Delpech, M. Gregoire, and E. Widom
Ultra-refractory Domains in the Oceanic Mantle Lithosphere Sampled as Mantle Xenoliths at Ocean Islands
J. Petrology, June 1, 2008; 49(6): 1223 - 1251.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
C. Bonadiman, M. Coltorti, S. Duggen, L. Paludetti, F. Siena, M. F. Thirlwall, and B. G. J. Upton
Palaeozoic subduction-related and kimberlite or carbonatite metasomatism in the Scottish lithospheric mantle
Geological Society, London, Special Publications, January 1, 2008; 293(1): 303 - 333.
[Abstract] [Full Text] [PDF]

Home page
 J PetrologyHome page
J.-H. YU, S. Y. O'REILLY, M. ZHANG, W. L. GRIFFIN, and X. XU
Roles of Melting and Metasomatism in the Formation of the Lithospheric Mantle beneath the Leizhou Peninsula, South China
J. Petrology, February 1, 2006; 47(2): 355 - 383.
[Abstract] [Full Text] [PDF]


Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.