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Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada
journal contribution
posted on 2023-05-17, 21:06 authored by Chen, W, Vadim Kamenetsky, Simonetti, AThe Earth's sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na- and K-bearing magmatic carbonates of nyerereite [Na 2 Ca(CO 3) 2 ] and gregoryite [(Na 2,K 2,Ca)CO 3 ]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic carbonates. Consequently, this leads to the conundrum as to the composition of primary, mantle-derived carbonatite liquids. Here we report a detailed chemical investigation of melt inclusions associated with intrusive (plutonic) calcite-rich carbonatites from the ∼120 Ma carbonatite complex of Oka (Canada). Melt inclusions are hosted by magnetite (Fe 3 O 4), which crystallizes through a significant period of carbonatite melt solidification. Our results indicate mineral assemblages within the melt inclusions that are consistent with those documented in natrocarbonatite lavas. We propose therefore that derivation of alkali-enriched parental carbonatite melts has been more prevalent than that preserved in the geological record.
Funding
Australian Research Council
History
Publication title
Nature CommunicationsVolume
4Article number
2687Number
2687Pagination
1-6ISSN
2041-1723Department/School
School of Natural SciencesPublisher
Nature Publishing GroupPlace of publication
London, UKRights statement
Copyright 2013 Macmillan PublishersRepository Status
- Restricted