Alkali-carbonate melts in the cratonic mantle evidenced by a wehrlite xenolith from the Majuagaa kimberlite, West Greenland

Kiseeva, Ekaterina S.; Kamenetsky, Vadim S.; Chayka, Ivan F.; Maas, Roland; Nielsen, Troels F. D.

Alkali-carbonate melts in the cratonic mantle evidenced by a wehrlite xenolith from the Majuagaa kimberlite, West Greenland

dc.contributor.author	Kiseeva, Ekaterina S.	en
dc.contributor.author	Kamenetsky, Vadim S.	en
dc.contributor.author	Chayka, Ivan F.	en
dc.contributor.author	Maas, Roland	en
dc.contributor.author	Nielsen, Troels F. D.	en
dc.contributor.funder	Natural Environment Research Council	en
dc.contributor.funder	Irish Research Council	en
dc.date.accessioned	2024-10-15T08:13:21Z
dc.date.available	2024-10-15T08:13:21Z
dc.date.issued	2024-10-09	en
dc.description.abstract	Carbonate melts are critically important for the deep carbon cycle, mantle melting, redox reactions, and transport of highly incompatible elements. The presence of carbonate melts in the cratonic mantle has been inferred from experimental studies, metasomatic transformations, and melt/fluid inclusions in xenoliths, kimberlites, and diamonds. However, the exact composition of such melts is difficult to determine due to their ephemeral nature and highly reactive properties. Once formed, they migrate away from the source and react with silicate mantle minerals, especially orthopyroxene, causing mantle metasomatism. Wehrlite is one of the products of interaction between the carbonate melt and peridotitic mantle and hence is an excellent candidate for locating in situ carbonate melts. Here, we report petrological, geochemical, and melt inclusion data for a garnet wehrlite xenolith in the Majuagaa kimberlite dike, West Greenland. The xenolith, which last equilibrated with the mantle at 4.5 GPa and 1000 °C, contains abundant melt pools composed of dolomite, calcite, serpentine, spinel, apatite, and phlogopite. Although the original magmatic mineralogy was largely destroyed by low-temperature alteration, remnants of the crystallized carbonatitic melt are preserved as primary melt inclusions in the liquidus Ti-Mg-Fe spinel. These melt inclusions, composed of carbonates, alkali carbonates, periclase/brucite, and minor halides, K-sulfide, apatite, and phlogopite, are the first direct evidence for in situ alkali-carbonate melt in the deep cratonic mantle. Compositionally, they are very similar to primary Na-dolomite melt found in experiments and in fluid inclusions within diamonds.	en
dc.description.sponsorship	Natural Environment Research Council (grant NE/L010828/1) and Irish Research Council (grant IRCLA/2022/2638)	en
dc.description.status	Peer reviewed	en
dc.description.version	Published Version	en
dc.format.mimetype	application/pdf	en
dc.identifier.citation	Kiseeva, E. S., Kamenetsky, V. S., Chayka, I. F., Maas, R. and Nielsen, T. F. D. (2024) 'Alkali-carbonate melts in the cratonic mantle evidenced by a wehrlite xenolith from the Majuagaa kimberlite, West Greenland', Geology. doi: https://doi.org/10.1130/G52274.1	en
dc.identifier.doi	https://doi.org/10.1130/g52274.1	en
dc.identifier.eissn	1943-2682	en
dc.identifier.issn	0091-7613	en
dc.identifier.journaltitle	Geology	en
dc.identifier.uri	https://hdl.handle.net/10468/16571
dc.language.iso	en	en
dc.publisher	Geological Society of America	en
dc.rights	© 2024, the Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.	en
dc.rights.uri	https://creativecommons.org/licenses/by/4.0/	en
dc.subject	Carbonate melts	en
dc.subject	Wehrlite	en
dc.subject	Majuagaa kimberlite dike	en
dc.subject	West Greenland	en
dc.title	Alkali-carbonate melts in the cratonic mantle evidenced by a wehrlite xenolith from the Majuagaa kimberlite, West Greenland	en
dc.type	Article (peer-reviewed)	en