Palaeomagnetism and the relation between the Bredåkra delta and the Fjärås Stadial and the Gothenburg Magnetic Excursion

Abstract

The Gothenburg Magnetic Excursion ended with a fully reversed “Flip” in the Fjärås Stadial dated at 12,350–12,400 B.P. The Bredåkra delta in south-eastern Sweden was formed during a climatic deterioration lasting for about 85 years. Palaeomagnetic measurements of three varved clay sequences are reported. A sequence covering the time of the formation of the Bredåkra delta possesses negative polarity (for 199 varves), correlatable with the Gothenburg Magnetic Excursion/Flip. Varves just pre-dating the delta formation show normal polarity. An older varve sequence (156 varves), probably dating from the Vintapper Interstadial/Low Baltic Stadial transition, also possesses negative polarity.