No short reversals of Brunhes Age recorded in the Toba Tuffs, north Sumatra, Indonesia

Abstract

Paleomagnetic and 40 Ar/ 39 Ar data indicate that two tuffs are present at Siguragura, North Sumatra, Indonesia: a reversely magnetized tuff (the earliest eruptive unit of the Toba caldera) of Matuyama age (0.84 Ma) and a normally magnetized tuff (the last eruptive unit of the Toba caldera) of late Brunhes age. No reversely magnetized tuffs of late Brunhes age are present at this location as suggested by previous investigators.