Meyer, N. A., Stachel, T., Pearson, D. G., Stern, R. A., Harris, J. W. and Walter, M. J. (2023) Diamonds reveal subducted slab harzburgite in the lower mantle. Geology, 51(3), pp. 238-241. (doi: 10.1130/g50675.1)
Text
290618.pdf - Published Version Available under License Creative Commons Attribution. 668kB |
Abstract
Characterizing compositional heterogeneity in Earth’s lower mantle is critical to understanding its dynamics. Three low-nitrogen diamonds from Koffiefontein (South Africa), containing inclusion assemblages of ferropericlase ± orthopyroxene ± magnesite, constrain diamond formation in an Mg-rich lower-mantle environment. Ferropericlase inclusions have Mg# 82.7–88.5 and orthopyroxene inclusions (retrogressed bridgmanite) have Mg# 95.0–95.1 and mantle-like δ18O of +5.6‰ ± 0.2‰. Magnesite included in one diamond implicates carbonated fluids in diamond formation. High Mg# and low Ca, Al, and Na of the assemblage indicate a melt-depleted meta-harzburgitic environment, in contrast to more fertile compositions expected for primitive lower mantle. Extremely low Ca in orthopyroxene inclusions may reflect a combination of melt depletion and low equilibration temperatures at the time of trapping. Inclusion compositions implicate subducted oceanic slab meta-harzburgite as the host for diamond growth. Mantle-like δ18O of the orthopyroxene inclusions indicates unaltered oceanic lithosphere. Similar melt-depleted characteristics in lower-mantle inclusion assemblages worldwide support that meta-harzburgite is the dominant host of lower-mantle diamonds.
Item Type: | Articles |
---|---|
Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Harris, Dr Jeff |
Authors: | Meyer, N. A., Stachel, T., Pearson, D. G., Stern, R. A., Harris, J. W., and Walter, M. J. |
College/School: | College of Science and Engineering > School of Geographical and Earth Sciences |
Journal Name: | Geology |
Publisher: | Geological Society of America |
ISSN: | 0091-7613 |
ISSN (Online): | 1943-2682 |
Published Online: | 20 January 2023 |
Copyright Holders: | Copyright © 2023 The Authors |
First Published: | First published in Geology 51(3): 238-241 |
Publisher Policy: | Reproduced under a Creative Commons license |
University Staff: Request a correction | Enlighten Editors: Update this record