Skip Navigation



Journal of Petrology Advance Access published online on April 7, 2006
Journal of Petrology, doi:10.1093/petrology/egl019
This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
47/8/1531    most recent
egl019v1
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 Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by BERLY, T. J.
Right arrow Articles by LAPIERRE, H.
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?

© The Author 2006. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oxfordjournals.org
Received April 23, 2006
Accepted March 10, 2006

Article

Supra-subduction Zone Pyroxenites from San Jorge and Santa Isabel (Solomon Islands)

THOMAS J. BERLY 1, JÖRG HERMANN 2, RICHARD J. ARCULUS 3 *, and HENRIETTE LAPIERRE 4 {dagger}

1 DEPARTMENT OF EARTH AND MARINE SCIENCES, AUSTRALIAN NATIONAL UNIVERSITY, CANBERRA, A.C.T. 0200, AUSTRALIA; LABORATOIRE DE GEODYNAMIQUE DES CHAINES ALPINES, UNIVERSITE JOSEPH FOURIER, 38400, ST. MARTIN D'HERES, FRANCE
2 RESEARCH SCHOOL OF EARTH SCIENCES, AUSTRALIAN NATIONAL UNIVERSITY, CANBERRA, A.C.T. 0200, AUSTRALIA
3 DEPARTMENT OF EARTH AND MARINE SCIENCES, AUSTRALIAN NATIONAL UNIVERSITY, CANBERRA, A.C.T. 0200, AUSTRALIA
4 LABORATOIRE DE GEODYNAMIQUE DES CHAINES ALPINES, UNIVERSITE JOSEPH FOURIER, 38400, ST. MARTIN D'HERES, FRANCE

* To whom correspondence should be addressed.
RICHARD J. ARCULUS, E-mail: Richard.Arculus{at}anu.edu.au


  Abstract

Peridotites associated with pyroxenites (with rare olivine and spinel) are exposed on the islands of San Jorge and Santa Isabel in the Solomon Islands. Orthopyroxenite occurs in large outcrops (≤100 m2) whereas websterite and clinopyroxenite occur as layers and veins/dykes in peridotites. The bulk compositions of the pyroxenites are characterized by high Mg2+/(Mg2+ + Fe2+) (0·78-0·91) and low Al2O3 (<2·7 wt %). Low rare earth element abundances are coupled with large ion lithophile element enrichments and positive Sr and Pb anomalies (primitive mantle-normalized) relative to adjacent rare earths. Temperatures of equilibration for the pyroxenites are between 950 and 1050°C. These relatively low temperatures, combined with the occurrence of primary fluid inclusions, suggest that the pyroxenites formed by interaction of peridotite protoliths with an aqueous fluid. Bulk-rock and mineral compositions of the orthopyroxenites are similar to those of mantle-derived pyroxenites, whereas the websterites have closer chemical affinity with crustal arc cumulates. Nevertheless, field relationships plus petrological, textural and geochemical evidence are consistent with formation of all pyroxenite types in supra-subduction zone mantle, resulting from metasomatism of peridotite by subducted Pacific Plate-derived fluid. Such a setting for pyroxenite has not previously been reported in detail. We propose that these processes produce mantle pyroxenite with compositions similar to crustal pyroxenite.

Keywords: mantle metasomatism; pyroxenite; supra-subduction zone.
{dagger}Deceased.
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
I. Baziotis, E. Mposkos, and P. D. Asimow
Petrogenesis of Ultramafic Rocks from the Ultrahigh-pressure Metamorphic Kimi Complex in Eastern Rhodope (NE Greece)
J. Petrology, May 1, 2008; 49(5): 885 - 909.
[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.