Ancient Massive Lava Flows Had Two Sources When Africa and Antarctica Split

Lava layers of the Karoo magma province are found at the Victoria Falls, Africa.

Credit: Arto Luttinen

“This kind of eruptions are culmination events of planetary evolution and have caused mass extinctions of life. Yet their origin remains an outstanding question of Earth history” Luttinen explainsThe scientists disagree, for example, whether an enormous ascending plume of hot aterial cused the generation of magmas from the core-mantle boundary.

“Previous geophysical research has indicated features suggestive of mantle plumes, whereas geochemical studies have concluded based on lava compositions that there was no plume and that the magmas formed when the temperature of the upper mantle gradually got higher under Pangea. The supercontinent acted like a kettle lid” Luttinen summarises.

The previous studies of magma sources have mainly focused on a certain part of the widespread lava formation, however. The study published on March 27 in the international journal Scientific Reports scrutinised compositions of lava samples across the whole region of ancient magma eruptions. Their chemical signatures indicate that lavas in different areas had a different origin.

“The magmas had in fact two contrasting sources. One of them was the upper mantle, as suggested in previous research, whereas the other was most probably a deep mantle plume. Involvement of two different magma sources explains previous contradictory results and presents an interesting new framework for future studies”, concludes Luttinen.

The research was funded by the Academy of Finland and is a part of the VALVE project (Volatiles and large volcanic eruptions).