INVESTIGATING THE PROVENANCE OF BLACK SAND IN ICELAND: LOCAL VS. DISTAL SOURCES
Tholeiitic basaltic glass from Vik Beach has a composition that most closely resembles that of basalts from the Bárðarbunga-Veidivötn volcanic system. Transitional-alkaline basaltic glass is also present and resembles basalts from the Katla-Eldgjá volcanic system. Plagioclase and clinopyroxene from Vik Beach are also compositionally similar to crystals from these systems, but there is some evidence for minor input of clinopyroxene crystals from the Eyjafjallajökull central volcano. All of these sources are in the SFVZ. Most of the siliceous glass has a compositional range similar to rhyolites produced from the Katla central volcano in the SFVZ; however, some of the siliceous glass grains appear to be sourced from volcanoes outside the SFVZ.
The results suggest surficial mixing of the sand at Vik Beach is moderate at best since only nearby (≤ 60 km) Bárðarbunga-Veidivötn and Katla-Eldgjá volcanic systems appear to be the main sources, despite the presence of several other potential volcanic sources in the SFVZ. This is probably related mainly to the large volumes of material that have been produced by these two systems. However, it appears that some of the siliceous glass from Vik Beach was sourced from other, more distal volcanic sources. This could indicate that siliceous volcanic detritus is transported over greater distances compared to the other grain types as a result of relative durability.