Journal article
Evidence for subduction-related signatures in the southern African lithosphere from the N-O isotopic composition of metasomatic mantle minerals
A Fitzpayne, A Giuliani, C Harris, E Thomassot, C Cheng, J Hergt
Geochimica Et Cosmochimica Acta | PERGAMON-ELSEVIER SCIENCE LTD | Published : 2019
Abstract
Current understanding of the fate of subducted material (and related fluids) in the deep Earth can be improved by combining major and trace element geochemistry with stable isotopic compositions of mantle rocks or minerals. Limited isotopic fractionation during high temperature processes means that significant deviations from mantle-like isotope ratios in mantle rocks probably result from recycling of surficial material. To determine the effects and origins of mantle metasomatic fluids/melts, new δ15N and δ18O data have been collected for thirteen mantle xenoliths – harzburgites, wehrlites, lherzolites, and MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) rocks – from the Bultfontein kimberli..
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Awarded by Centre of Excellence for Core to Crust Fluid Systems, Australian Research Council
Funding Acknowledgements
We thank Graham Hutchinson and Alan Greig for their help during EPMA and LA-ICP-MS sessions, respectively. We also thank the De Beers Group, the University of Cape Town "John J. Gurney Upper Mantle Research Collection", Phil Janney, and Simon Shee, for providing unrivalled access to the studied samples, as well as Jock Robey for his help during fieldwork in the Kimberley area. Sherissa Roopnarain helped with the O isotope analyses at UCT. E. Thomassot thanks the IPGP and the Stable Isotope Geochemistry group for welcoming her as a CNRS fellow. Ashton Soltys and Hayden Dalton provided constructive and stimulating discussion as well as informal reviews of parts of this manuscript. We also thank James Day for editorial handling, as well as Ralf Halama and Sonja Aulbach for their highly constructive suggestions, which greatly improved the contents of this article. AF's PhD research is supported by the Gilbert Rigg scholarship from the University of Melbourne. AG acknowledges funding from the Australian Research Council through a Discovery Early Career Researcher Award (DECRA; award no. DE-150100009). This is publication 42 from the Kimberlites and Diamonds (KiDs) research group at the University ofMelbourne (https://kimberlitesdiamonds.org), also listed as contribution 1325 from the ARC Centre of Excellence for Core to Crust Fluid Systems (https://www.ccfs.mq.edu.au), 1302 in the GEMOC Key Centre (https://www.gemoc.mq.edu.au), and 2691 in the CRPG (https://www.crpg.cnrs-nancy.fr/).