Marine records reveal multiple phases of Toba’s last volcanic activity

Benoît Caron (1) , Giulia Del Manzo (1, 2) , Benoît Villemant (1) , Annachiara Bartolini (3) , Eva Moreno (4) , Anne Le Friant (2) , François Baudin (1) , Ana Alves (3)

1 iSTeP - Institut des Sciences de la Terre de Paris
2 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
3 CR2P - Centre de Recherche en Paléontologie - Paris
4 VOG - Variabilité de l'Océan et de la Glace de mer

The Indonesian Young Toba Tuff (YTT), classically dated around 74 ka BP, is considered as a shortlived explosive cataclysmic super-eruption. The huge amounts of ash and SO 2 emitted are likely to have triggered a volcanic winter which accelerated the transition to the last glaciation, and may have induced a human genetic bottleneck. However, the global climatic impact of the YTT or its duration are hotly debated. The present work offers a new interpretation of the Toba volcanic complex eruptive history. Analysing the BAR94-25 marine core proximal to the Toba volcanic center and combining it with high-resolution tephrostratigraphy and δ 18 O stratigraphy, we show that the Toba complex produced a volcanic succession that consists of at least 17 distinct layers of tephra and cryptotephra. Textural and geochemical analyses show that the tephra layers can be divided in 3 main successive volcanic activity phases (VAP1 to VAP3) over a period of ~ 50 kyr. The main volcanic activity phase, VAP2, including the YTT, is likely composed of 6 eruptive events in an interval whose total duration is ~ 10 ka. Thus, we suggest that the eruptive model of the Toba volcano must be revised as the duration of the Toba volcanic activity was much longer than suggested by previous studies. The implications of re-estimating the emission rate and the dispersion of ashes and SO 2 include global environmental reconstitutions, climate change modelling and possibly human migration and evolution.

Domaines: Planète et Univers [physics]

Benoît Caron, Giulia Del Manzo, Benoît Villemant, Annachiara Bartolini, Eva Moreno, et al.. Marine records reveal multiple phases of Toba’s last volcanic activity. Scientific Reports, 2023, 13 (1), pp.11575. ⟨10.1038/s41598-023-37999-w⟩. ⟨hal-04173473⟩