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Djerfisherite in kimberlites and their xenoliths: implications for kimberlite melt evolution

Citation

Abersteiner, A and Kamenetsky, VS and Goemann, K and Golovin, AV and Sharygin, IS and Giuliani, A and Rodemann, T and Spetsius, ZV and Kamenetsky, M, Djerfisherite in kimberlites and their xenoliths: implications for kimberlite melt evolution, Contributions to Mineralogy and Petrology, 174 Article 8. ISSN 0010-7999 (2019) [Refereed Article]

Copyright Statement

Copyright 2019 Springer-Verlag GmbH Germany, part of Springer Nature

DOI: doi:10.1007/s00410-018-1540-8

Abstract

Djerfisherite (K6(Fe,Ni,Cu)25S26Cl) occurs as an accessory phase in the groundmass of many kimberlites, kimberlite-hosted mantle xenoliths, and as a daughter inclusion phase in diamonds and kimberlitic minerals. Djerfisherite typically occurs as replacement of pre-existing FeNiCu sulphides (i.e. pyrrhotite, pentlandite and chalcopyrite), but can also occur as individual grains, or as poikilitic phase in the groundmass of kimberlites. In this study, we present new constraints on the origin and genesis of djerfisherite in kimberlites and their entrained xenoliths. Djerfisherite has extremely heterogeneous compositions in terms of Fe, Ni and Cu ratios. However, there appears to be no distinct compositional range of djerfisherite indicative of a particular setting (i.e. kimberlites, xenoliths or diamonds), rather this compositional diversity reflects the composition of the host kimberlite melt and/or interacting metasomatic medium. In addition, djerfisherite may contain K and Cl contents less than the ideal formula unit. Raman spectroscopy and electron backscatter diffraction (EBSD) revealed that these KCl poor sulphides still maintain the same djerfisherite crystal structure. Two potential mechanisms for djerfisherite formation are considered: (1) replacement of pre-existing FeNiCu sulphides by djerfisherite, which is attributed to precursor sulphides reacting with metasomatic KCl bearing melts/fluids in the mantle or the transporting kimberlite melt; (2) direct crystallisation of djerfisherite from the kimberlite melt in groundmass or due to kimberlite melt infiltration into xenoliths. The occurrence of djerfisherite in kimberlites and its mantle cargo from localities worldwide provides strong evidence that the metasomatising/infiltrating kimberlite melt/fluid was enriched in K and Cl. We suggest that kimberlites originated from melts that were more enriched in alkalis and halogens relative to their whole-rock compositions.

Item Details

Item Type:Refereed Article
Keywords:djerfisherite, kimberlite, sulphides, metasomatism, potassium, chlorine, diamond
Research Division:Earth Sciences
Research Group:Geology
Research Field:Mineralogy and Crystallography
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
UTAS Author:Abersteiner, A (Mr Adam Abersteiner)
UTAS Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
UTAS Author:Goemann, K (Dr Karsten Goemann)
UTAS Author:Rodemann, T (Dr Thomas Rodemann)
UTAS Author:Kamenetsky, M (Dr Maya Kamenetsky)
ID Code:129983
Year Published:2019
Funding Support:Australian Research Council (DP130100257)
Web of Science® Times Cited:4
Deposited By:CODES ARC
Deposited On:2019-01-03
Last Modified:2019-12-11
Downloads:0

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