Abstract

Iceland’s 500 km of active neovolcanic zones provides a high-resolution and spatially continuous transect across a mantle plume. Basalts erupted near the plume centre carry geochemical signatures such as high 3He/4He that suggest melting of a primitive mantle component. Yet trace elements and lithophile isotope signatures also point to the presence of enriched, recycled oceanic lithosphere in the Icelandic mantle source. Boron is an excellent tracer of recycled material, because it re-introduced to the mantle through subduction of serpentinized oceanic lithosphere.

In this talk I will present new boron isotope measurements from suite of crystal-hosted melt inclusions from North Iceland. Do Icelandic magmas carry any distinctive boron isotopic signatures indicative of recycled crustal material? How are mantle-derived boron isotopic signatures modified by crustal assimilation? To what extent can boron isotopic heterogeneity be resolved on the lengthscale of a mantle plume?