Youngest Toba Tuff in the Son Valley, India: a weak and discontinuous stratigraphic marker

E. Gatti (1) , A.J. Durand (2, 3, 4) , P.L. Gibbard (1) , Clive Oppenheimer (5, 6)

1 Department of Geography [Cambridge, UK]
2 Centre for Atmospheric Science [Cambridge, UK]
3 NILU - Norwegian Institute for Air Research
4 Department of Geological and Mining Engineering and Sciences
5 CAM - University of Cambridge [UK]
6 ISTO - Institut des Sciences de la Terre d'Orléans

Investigation of the climatic and environmental impacts of the Youngest Toba Tuff (YTT, ∼74 ka BP) eruption of Toba volcano, Sumatra, is crucial for understanding the consequences of the eruption for contemporaneous human populations. The Middle Son Valley, in India, was the first locality on the Indian subcontinent where the YTT was reported. The ash bed forms a discontinuous layer stretching for over 30 km along the river. Here we report on the stratigraphic contexts of YTT ash layers in alluvial deposits of the Middle Son Valley, in order to reconstruct the taphonomy of the ash deposits and the dynamic of their deposition. Although the distal ash has been studied since the 1980s, its stratigraphic integrity and the mechanisms and pathways involved in its transport and deposition have bit previously been assessed. We find that the YTT occurrences in the Middle Son Valley may not be reliable chronostratigraphical markers for millennial scale palaeoenvironmental reconstruction.

Mots clés: Toba; Son Valley; Tephra; Fluvial geomorphology

Domaines: Volcanologie; Milieux et Changements globaux

E. Gatti, A.J. Durand, P.L. Gibbard, Clive Oppenheimer. Youngest Toba Tuff in the Son Valley, India: a weak and discontinuous stratigraphic marker. Quaternary Science Reviews, 2011, 30 (27-28), pp.3925-3934. ⟨10.1016/j.quascirev.2011.10.008⟩. ⟨insu-00707153⟩