The sub-lithospheric source of North Atlantic basalts: Evidence for, and significance of, a common end-member

Ellam, R.M. and Stuart, F.M. (2000) The sub-lithospheric source of North Atlantic basalts: Evidence for, and significance of, a common end-member. Journal of Petrology, 41(7), pp. 919-932. (doi: 10.1093/petrology/41.7.919)

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Palaeogene basalts from the margins of the North Atlantic often show geochemical variations that are consistent with their parental magmas having interacted with the lithosphere en route to the Earth's surface. These geochemical trends vary depending on the nature of the local lithospheric contaminants. Using examples from the British Tertiary Igneous Province and SE Greenland, we construct coherent contamination trends, which converge on a restricted Pb isotope composition, apparently indicating a common uncontaminated asthenospheric mantle component. Significantly, this composition is also suitable as one end-member of the Pb isotope arrays recorded in Recent Icelandic basalts. We conclude that this composition has been a persistent component of the Iceland plume over 60 my, dominating the mantle contribution to the Palaeocene phase of flood basalt magmatism but constituting only one end-member on Iceland. The Pb isotope composition of this 'North Atlantic end-member' is consistent with, but not necessarily demanding of, a primordial source. Recent evidence suggesting a lower- mantle origin for mantle plumes encourages investigation of whether the geochemical evidence supports that hypothesis. Helium isotope data from Palaeogene North Atlantic basalts support a lower-mantle contribution. However, mixing models suggest that it is untimely that the lower-mantle contribution is large enough to dominate the Sr-Nd-Pb isotope compositions and lithophile trace element signatures of any plume-derived basalts.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Ellam, Professor Rob and Stuart, Professor Fin
Authors: Ellam, R.M., and Stuart, F.M.
Subjects:Q Science > QE Geology
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Journal of Petrology

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