Transient high temperatures in mantle plume heads inferred from magnesian olivines in Phanerozoic picrites

R. N. Thompson () and S. A. Gibson
Additional contact information
R. N. Thompson: Department of Geological Sciences University of Durham
S. A. Gibson: University of Cambridge

Nature, 2000, vol. 407, issue 6803, 502-506

Abstract: Abstract Both scaled laboratory experiments and numerical models of terrestrial mantle plumes produce ‘balloon-on-a-string’ structures, with a bulbous head followed by a stem-like tail. Discussions have focused on whether their initial upwelling heads are hotter than the tails or cooler, as a result of entrainment of ambient mantle during ascent1,2,3, and also on whether initial plume upwelling is a newtonian or non-newtonian process4,5. The temperature of the mantle delivered to the base of the lithosphere is a critical parameter in such debates. Dry continental magmas can normally contribute little to this topic because their hottest (ultramafic) examples can be expected to be trapped, owing to their density, beneath the Moho. Here we report a rare case in which olivine (with 93.3% forsterite; Mg2SiO4) phenocrysts, precipitated from an unerupted komatiitic melt (∼24% MgO) of the Tristan mantle plume head 132 Myr ago, were carried to upper-crust levels in northwest Namibia by less Mg-rich (9.6–18.5% MgO) magmas. We infer that the hidden melt, generated when the plume impinged on the base of the lithosphere, originated in the mantle with a potential temperature of ∼1,700 °C. This is ∼400 °C above ambient and much hotter than the temperatures previously calculated for steady-state Phanerozoic mantle plumes3,6,7,8. Published data show that the same conclusion can be reached for the initial Iceland and Galapagos plumes.

Date: 2000
References: Add references at CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
https://www.nature.com/articles/35035058 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:407:y:2000:i:6803:d:10.1038_35035058

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/35035058

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().