Constraining the isotopic endmembers contributing to 1.1 Ga Keweenawan large igneous province magmatism

Tyrone O. Rooney, Jasper G. Konter, Valerie A. Finlayson, Andrew LaVigne, Eric L. Brown, Carol A. Stein, Seth Stein, Robert Moucha

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Continental flood basalt lavas often contain deeply-sourced, thermo-chemically anomalous material that can provide a potential probe of inaccessible reservoirs. However, continental flood basalts interact with geochemically diverse domains within the continental lithosphere, which may complicate interpretations of deep mantle signatures. We examine the role of continental lithospheric mantle in continental flood basalts erupted as part of the 1.1 Ga Keweenawan large igneous province, centered on the Lake Superior region of North America. We show that flood basalts at Mamainse Point exhibit a range of εHf 1100 from −14.1 to +6, plotting along the global εHf—εNd mantle array. Lithospheric mantle melts represented by alkaline rocks from the Coldwell and Seabrook Lake Complexes yield positive εNd 1100 (+0.7 to +4.3) and εHf 1100 from −6.9 to +2.4, placing them below the mantle array. Mamainse Point lavas are interpreted to be variably crustally contaminated melts of the Keweenawan plume and ambient upper mantle; there is no clear evidence for contributions from an enriched lithospheric mantle.

Original languageEnglish (US)
Article number49
JournalContributions to Mineralogy and Petrology
Volume177
Issue number4
DOIs
StatePublished - Apr 2022

Keywords

  • Continental lithospheric mantle
  • Hf isotopes
  • Intra-plate processes
  • Keweenawan large igneous province
  • Mantle processes
  • Mid-continent rift

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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