Helium isotope evidence for a deep-seated mantle plume involved in South Atlantic breakup

TitleHelium isotope evidence for a deep-seated mantle plume involved in South Atlantic breakup
Publication TypeJournal Article
Year of Publication2017
AuthorsStroncik N.A, Trumbull R.B, Krienitz M.S, Niedermann S., Romer R.L, Harris C., Day JMD
JournalGeology
Volume45
Pagination827-830
Date Published2017/09
Type of ArticleArticle
ISBN Number0091-7613
Accession NumberWOS:000408588700017
Keywordsconstraints; crustal contamination; geochemical evidence; high he-3/he-4 ratios; hotspot; messum igneous complex; namibia; phenocrysts; tristan plume; volcanism
Abstract

Earth history has been punctuated by episodes of short-lived (<10 m.y.), high-volume (>10(6) km(3)) magmatism. The origin of these events and their manifestations as large igneous provinces (LIPs) with associated continental flood basalts do not fit in the current plate-tectonic paradigm. Upper-mantle processes have been invoked for some LIPs, whereas the origin of others appears to be related to plumes rising from the deep mantle. The Parana-Etendeka LIP has remained enigmatic and highly contested in terms of plume versus upper-mantle models. Here, we provide evidence for a plume origin based on new isotopic (He, O, Sr, Nd, Pb) and trace-element data from olivine-rich dikes from Namibia. The composition of the dikes can be explained by mixing at shallow depths between a plume source with high He-3/He-4 (>26 R-A) and ambient asthenospheric mantle, before ascent through the thinning lithosphere.

DOI10.1130/g39151.1
Short TitleGeology
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