Journal article

New constraints on the source, composition, and post-emplacement modification of kimberlites from in situ C-O-Sr-isotope analyses of carbonates from the Benfontein sills (South Africa)

Montgarri Castillo-Oliver, Andrea Giuliani, William L Griffin, Suzanne Y O'Reilly, Russell N Drysdale, Adam Abersteiner, Emilie Thomassot, Xian-Hua Li



Primary carbonates in kimberlites are the main CO2 carriers in kimberlites and thus can be used to constrain the original carbon and oxygen-isotope composition of kimberlite melts and their deep mantle sources. However, the contribution of syn- and post-emplacement processes to the modification of the C–O-isotope composition of kimberlites is yet to be fully constrained. This study aims to shed new light on this topic through a detailed textural, compositional (major and trace elements), and in situ C–O–Sr isotopic characterisation of carbonates in the Benfontein kimberlite sills (Kimberley, South Africa). Our multi-technique approach not only reveals the petrographic and geochemical complex..

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Awarded by Australian Research Council

Awarded by Swiss National Science Foundation

Awarded by European Science Foundation-Europlanet 2020 Consortium

Awarded by ARC Centre of Excellence for Core to Crust Fluid Systems

Funding Acknowledgements

We would like to thank Jock Robey for invaluable support during field work in the Kimberley area, the De Beers group for providing access to the Benfontein Farm, and Ashton Soltys and Manal Bebbington for their help with sample selection and preparation. The authors also wish to acknowledge Juan Diego Martin, Xavier Llovet, and Eva Prats for their assistance with the CL system, EMPA, and SEM analysis at the Serveis Cientifico-Tecnics (UB); as well as Yoann Greau, Sarah Gain, Rosanna Murphy, Yi-Jen Lai, and Hadrien Henry for their help with the SEM, LA-ICP-MS, and LA-MC-ICP-MS analysis at Macquarie University GeoAnalytical (MQGA, formerly GAU). We would also like to thank Etienne Deloule, Johan Villeneuve, and David Madre for their help with the SIMS analysis at Centre de Recherches Petrographiques et Geochimiques (CRPG) in Nancy (France); as well as Hongxia Ma, Xiaoxiao Ling, Jiao Li, Yu Liu, and Guoqiang Tang at the Institute of Geology and Geophysics, Chinese Academy of Sciences in Beijing (China). This research was supported by the Australian Research Council (Discovery Early Career Researcher Award to AG; Grant no. DE-150100009); the Swiss National Science Foundation (Ambizione fellowship to AG; Grant no. PZ00P2_180126/1); the European Science Foundation-Europlanet 2020 Consortium (Project no. 16-EPN2-017); as well as funds from the ARC Centre of Excellence for Core to Crust Fluid Systems (CE110001017). This study used instrumentation funded by ARC Linkage Infrastructure, Equipment and Facilities (LIEF) and Department of Education, Science and Training (DEST) Systemic Infrastructure Grants, Macquarie University, National Collaborative Research Infrastructure Scheme (NCRIS) AuScope and Industry. This is contribution 1421 from the ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and 1364 in the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC). Careful editorial handling by Daniela Rubato, and comments by Sebastian Tappe and an anonymous reviewer greatly improved the contents of this manuscript.