High-K alkali basalts of the Western Snake River Plain (Idaho): Abrupt transition from tholeiitic to mildly alkaline plume-derived basalts

John W. Shervais, Scott K. Vetter

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Basaltic volcanism in the western Snake River Plain underwent an abrupt change circa ~ 700 ka to 900 ka, from low-K tholeiitic basalt and ferrobasalt to high-K transitional alkali basalt. The low-K tholeiitic basalts share major element, trace element, and isotopic characteristics with olivine tholeiites of the eastern Snake River Plain, and must have been derived by similar processes from similar sources. In contrast, the younger high-K alkali basalts share major element, trace element, and isotopic characteristics with plume-derived alkali basalts of ocean islands suites like Hawaii. We conclude that this abrupt transition reflects either or both the erosion of pre-existing mantle lithosphere in the wake of the Yellowstone-Snake River plume, or the depletion of this lithosphere in fusible components so that it no longer contributed to the overall mass flux of magma. The abruptness of the transition implies that it may have a catastrophic origin, such as lithospheric delamination caused by a Rayleigh-Taylor instability beneath the Idaho batholith.

Original languageEnglish (US)
Pages (from-to)141-152
Number of pages12
JournalJournal of Volcanology and Geothermal Research
Volume188
Issue number1-3
DOIs
StatePublished - Nov 20 2009

Bibliographical note

Funding Information:
Our work was supported by NSF grants EAR-9526594, EAR-9526722, and EAR-9526723, and by EDAMP grants in 1998, 1999, and 2004.

Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.

Keywords

  • high-K basalts
  • hotspots
  • Snake River Plain
  • SRP
  • Yellowstone plume

Continental Scientific Drilling Facility tags

  • HOTSPOT

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