Skip Navigation


Journal of Petrology Advance Access first published online on May 20, 2005
This version published online on May 27, 2005
Journal of Petrology, doi:10.1093/petrology/egi047
This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
46/10/2059    most recent
egi047v2
egi047v1
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 VILJOEN, K. S.
Right arrow Articles by QUADLING, A. G.
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 2005. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oupjournals.org
Received March 15, 2004
Accepted April 4, 2005

Article

Contrasting Group I and Group II Eclogite Xenolith Petrogenesis: Petrological, Trace Element and Isotopic Evidence from Eclogite, Garnet-Websterite and Alkremite Xenoliths in the Kaalvallei Kimberlite, South Africa

K. S. VILJOEN 1*, D. J. SCHULZE 2, and A. G. QUADLING 3

1 GEOSCIENCE CENTRE, DE BEERS CONSOLIDATED MINES LTD, P.O. BOX 82232, SOUTHDALE, 2135, SOUTH AFRICA; BERNARD PRICE INSTITUTE OF GEOPHYSICAL RESEARCH, HUGH ALLSOPP LABORATORY, UNIVERSITY OF THE WITWATERSRAND, PRIVATE BAG 3, WITS, JOHANNESBURG, 2050, SOUTH AFRICA
2 DEPARTMENT OF GEOLOGY, UNIVERSITY OF TORONTO, ERINDALE COLLEGE, MISSISSAUGA, ONTARIO, CANADA L5L 1C6
3 GEOSCIENCE CENTRE, DE BEERS CONSOLIDATED MINES LTD, P.O. BOX 82232, SOUTHDALE, 2135, SOUTH AFRICA

* To whom correspondence should be addressed.
K. S. VILJOEN, E-mail: fanus.viljoen{at}debeersgroup.com


  Abstract

Eclogite xenolith varieties at Kaalvallei include accessory-free bimineralic xenoliths, diamond-bearing eclogite, corundum-bearing eclogite, garnet-websterite, alkremite and spinel-bearing eclogite. The xenoliths can be accurately classified into previously defined Group I and Group II varieties on both petrographic and geochemical principles. Kaalvallei Group I eclogites (including diamond-bearing eclogite) are considered to derive from a heterogeneous protolith. Eclogite genesis might have been by residue formation associated with the dehydration and partial melting of a protolith consisting of variably mixed, subducted ocean floor basalt and sediment. Kaalvallei Group II eclogite xenoliths are likely to have formed through crystallization of small-volume melts within conduits in old, enriched subcontinental lithosphere. Kaalvallei websterite xenoliths might be petrogenetically related to Group II xenoliths. Isotopic data for Kaalvallei corundum-bearing eclogite and alkremite xenoliths do not provide constraints on petrogenesis. Spinel-bearing eclogite xenoliths are ultradepleted in virtually all trace elements, with very low light rare earth element contents, relatively high heavy rare earth element concentrations, extreme 87Sr/86Sr (~0·915) and extreme 143Nd/144Nd (0·517) isotopic compositions. These xenoliths are considered to be the residues of a partial melting event.

Keywords: eclogite xenoliths; trace elements; REE; isotopic composition; diamonds.
Tables 2 and 7 have been updated in this version
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
 South African Journal of GeologyHome page
A.E. Moore
Type II diamonds: Flamboyant Megacrysts?
South African Journal of Geology, March 1, 2009; 112(1): 23 - 38.
[Abstract] [Full Text] [PDF]

Home page
 South African Journal of GeologyHome page
S. Dludla, A. P. le Roex, and J. J. Gurney
Eclogite xenoliths from the Premier kimberlite, South Africa: geochemical evidence for a subduction origin
South African Journal of Geology, September 1, 2006; 109(3): 353 - 368.
[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.