Icelandic Volcanic Rocks Isotopic Database (IVID)

We compile a new geochemical database (Icelandic Volcanic rocks Isotopic
Database, IVID) which includes previously reported 87Sr/86Sr, 143Nd/144Nd,
176Hf/177Hf, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 187Os/188Os and
3He/4He data and major and trace element concentrations measured in
Icelandic volcanic rocks. Isotopic compositions were evaluated, and
filtered to identify the highest quality data and data most likely to
represent mantle-derived compositions. The carefully filtered,
comprehensive geochemical database is an important contribution to the
geochemical community and can be used to put further constraints on the
generation of geochemical heterogeneity in Iceland. We use the compiled
database to examine the spatial distribution of geochemical components in
the Icelandic mantle, and test whether melting processes control how
source heterogeneity from the deep mantle is extracted on the surface. The
PRIMELT software (which combines an inverse model for crystallization in
the crust with a forward model of mantle melting to estimate the primary
mantle-derived magma composition) is used to estimate mantle potential
temperatures and melt fractions in Iceland. The results of these
calculations and forward melting models demonstrate that mantle potential
temperatures have a largely insignificant role and that lithospheric
thickness plays a key role in generating geochemical heterogeneity in
Icelandic volcanic rocks. Volcanic rocks from the off-rift volcanic zones
are generally produced by lower melt fractions, consistent with
preferential sampling of geochemically enriched and fertile “blobs” at
lower degrees of melting, where the lithosphere is thicker; more
geochemically depleted volcanic rocks from the axial rift zones, where the
lithosphere is thinner, show higher degrees of melting, consistent with
dilution of enriched blob melts by melts of more depleted and refractory
mantle.