Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Geology Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Geology; July 2005; v. 33; no. 7; p. 565-568; DOI: 10.1130/G21637.1
© 2005 Geological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
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 Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (17)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Tappert, R.
Right arrow Articles by Brey, G. P.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Subducting oceanic crust: The source of deep diamonds

Ralf Tappert1, Thomas Stachel1, Jeff W. Harris2, Karlis Muehlenbachs3, Thomas Ludwig4 and Gerhard P. Brey5

1 Department of Earth and Atmospheric Sciences, 1-26 Earth Science Building, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
2 Division of Earth Sciences, Gregory Building, Lilybank Gardens, University of Glasgow, Glasgow G12 8QQ, UK
3 Department of Earth and Atmospheric Sciences, 1-26 Earth Science Building, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
4 Institut für Mineralogie, Ruprecht Karls Universität, Im Neuenheimer Feld 236, 69120 Heidelberg, Germany
5 Institut für Mineralogie, J.W. Goethe Universität, Senckenberganlage 28, 60054 Frankfurt, Germany

Inclusions of majoritic garnet in diamonds from the Jagersfontein kimberlite formed at unusually great depths of ~250 to >500 km in the asthenosphere and transition zone. The original host rocks were derived from a much shallower, basaltic (eclogitic) source. The presence of negative Eu anomalies in all majoritic garnets requires a crustal origin, thereby linking these very deep diamond sources to subducting oceanic crust. The carbon isotope values ({delta}13C) of the host diamonds fall within a narrow range at ~–20{per thousand}, which is fundamentally different from the broad range (–24{per thousand} to –2{per thousand}) and bimodal distribution of carbon isotopes of Jagersfontein diamonds that formed in the shallower lithosphere. This indicates that majoritic garnet-bearing diamonds at Jagersfontein inherited their light carbon isotopic composition directly from organic matter contained in a subducting slab. These diamonds were likely formed by direct conversion from graphite, well within the diamond stability field.

Key Words: majorite • diamonds • inclusions • mantle • Eu anomalies • organic carbon




This article has been cited by other articles:


Home page
 GeologyHome page
R. Tappert, J. Foden, T. Stachel, K. Muehlenbachs, M. Tappert, and K. Wills
Deep mantle diamonds from South Australia: A record of Pacific subduction at the Gondwanan margin
Geology, January 1, 2009; 37(1): 43 - 46.
[Abstract] [Full Text] [PDF]

Home page
 South African Journal of GeologyHome page
M. de Wit
The Kalahari Epeirogeny and climate change: differentiating cause and effect from core to space
South African Journal of Geology, September 1, 2007; 110(2-3): 367 - 392.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Geological Society of America