Abstract

Assessing primary volatile heterogeneity of the mantle beneath Icelandic is an essential requirement before the role of secondary modifications following the release and transport of volatiles from the mantle-crust system, can be evaluated. Recently published stable isotope data (δD, δ15N and δ37C) suggest that the Icelandic mantle samples at least two distinct mantle volatile reservoirs that (i) preserve the geochemical signatures of Earth’s heterogeneous accretion and (ii) show strong evidence for recycled crustal material trapped by the Iceland plume source. Our ongoing work, involving a suite of subglacially erupted basalts along with melt inclusions and sulfide minerals present in mafic minerals from primitive Icelandic basalts, on the stable isotopic composition of H2O (δD), O (δ18O) and S (δ33S, δ34S and δ36S), aims at evaluating volatile heterogeneity present in the Icelandic mantle. By combining our results with trace element ratios (H2O/Ce, Cl/Nb and S/Dy) and radiogenic isotopes (Sr, Nd, Hf and Pb), we can test for modification of mantle-derived stable isotope values and constrain better the degree of volatile heterogeneity in Iceland mantle and, in particular the mantle plume source.

Sæmundur A. Halldórsson, Jaime D. Barnes, Andri Stefánsson, David R. Hilton, Erik H. Hauri, Edward W. Marshall, 2016. Subducted lithosphere controls halogen enrichments in the Iceland mantle plume source. Geology 44, 679-682, doi:10.1130/G37924.1.

Sæmundur A. Halldórsson, David R. Hilton, Peter H. Barry, Evelyn Füri and Karl Grönvold, 2016. Recycling of crustal material by the Iceland mantle plume: new evidence from nitrogen elemental and isotope systematics of subglacial basalts. Geochemica Cosmochimica Acta, Volume 176, Pages 206-226. doi:10.1016/j.gca.2015.12.021.

*Lydia J. Hallis, Gary R. Huss, Kazuhide Nagashima, G. Jeffrey Taylor, Sæmundur Ari Halldórsson, David R. Hilton, Mike J. Mottl and Karen J. Meech 2015. Evidence for primordial water in Earth’s deep mantle. Science. Volume 350, 6262, 795-797, doi: 10.1126/science.aac4834.