A volcanic eruption in Iceland opened a rare window for scientists

The eruption at Fagradalsfjäll began in March and ended in September 2021 and was the volcano’s first eruption in a populated part of Iceland in nearly 800 years.

An international research team took the opportunity to collect samples of lava several times a week. This is to create a chronological record of the samples and to follow the geochemical evolution of the eruption in detail.

The outbreak can be monitored in real time

When volcanologists investigate ancient eruptions, they usually work with a limited picture of material from the eruption, for example, old lava flows can be buried in whole or in part by new currents. However, at Fagradalsfjäll, the eruption was well monitored and samples were taken often so that researchers can document the development of the eruption in near real time.

The researchers were interested in oxygen isotopes. Igneous rocks consist of about 50 percent oxygen, and with the help of the ratios between oxygen isotopes, the origin of materials can be traced from the mantle and crust.

Using isotopes of oxygen, scientists can thus determine whether the magma originates from the mantle or whether it has interacted with the Earth’s crust on its way to the surface.

Several surprises

When it comes to many of the remaining elements that make up igneous rocks, in addition to oxygen, the results revealed several surprises. For example, researchers note that the contents of this volcanic eruption covered about half of the mantle magma diversity previously documented in all of Iceland.

In summary, geochemical results show that magma from the last eruption in Iceland originates from several different locations in the Earth’s mantle with its own distinct elemental properties.

Better understanding of the abaya

To the researchers’ surprise, all regions had identical oxygen isotope ratios. The result was remarkable and had not previously been observed in an active eruption.

The new study provides compelling new evidence that distinct mantle magmas have uniform oxygen isotope ratios, which could help scientists better understand mantle dynamics and improve Iceland’s mantle models.

The study is a collaboration between the University of Oregon, Uppsala University, the University of Iceland and Deutsches GeoForschungsZentrum (GFZ)

Scientific study

Diverse mantle components with stable oxygen isotopes in the 2021 Vajradals eruptionIcelandNature Communications.

Contact

Francis Deegan, Researcher in the Department of Geosciences, Uppsala University, [email protected]

Valentin Troll, Professor in the Department of Geosciences, Uppsala University, [email protected]