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Mantle melting versus mantle metasomatism - “The chicken or the egg” dilemma

Citation

Kiseeva, ES and Kamenetsky, VS and Yaxley, GM and Shee, SR, Mantle melting versus mantle metasomatism - 'The chicken or the egg' dilemma, Chemical Geology: An International Journal, 455 pp. 120-130. ISSN 0009-2541 (2017) [Refereed Article]


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Copyright Statement

© 2016 The Authors. Published by Elsevier B.V. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1016/j.chemgeo.2016.10.026

Abstract

Most eclogitic mantle xenoliths brought to the surface exhibit a certain degree of enrichment with incompatible elements, usually attributed to the effect of mantle metasomatism by a putative metasomatic fluid. The metasomatic overprint is represented mainly by enrichments in Na, K, Ba, Ti and LREE and the original source of this fluid remains unknown. In this paper, we present a detailed petrological study of a typical eclogitic mantle xenolith from the Roberts Victor kimberlite mine in South Africa. We find that its textural and mineralogical features present strong evidence for incipient melting. The melting assemblage we observe did not necessarily require introduction of additional components, that is: in-situ melting alone could produce highly incompatible element enriched melt without involvement of a hypothetical and speculative "metasomatic event". Due to the higher abundance in incompatible elements and lower solidus temperature than peridotites, mantle eclogites, some of which represent previously subducted oceanic crust, are much more plausible sources of mantle metasomatism, but on the other hand, they can be considered as highly metasomatised themselves. This brings us to the "chicken or egg" dilemma – was the secondary mineral assemblage in mantle lithologies a result or a source of mantle metasomatism?

Item Details

Item Type:Refereed Article
Keywords:kimberlite-borne xenolith, Roberts Victor, carbonated eclogite, incipient melting, cratonic mantle, secondary mineral assemblage
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and Metamorphic Petrology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:118132
Year Published:2017
Deposited By:CODES ARC
Deposited On:2017-07-05
Last Modified:2017-11-13
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