High-resolution paleomagnetic dating of sediments deposited in the central Baltic Sea during the last 3000 years

Abstract

Abstract Sediment cores from the main sedimentary basin in the Baltic Sea, the Gotland Deep, provide a high-resolution record of changes in the Holocene paleo-environment and paleoclimate. Due to the inherent inaccuracy (reservoir effect, redeposited material) of the 14 C dating method in dating marine sediments, the known changes in the Earth's magnetic field recorded in three sediment cores from the Gotland Deep were used to produce a more detailed and accurate timescale. The variations in the inclination and declination were compared to the paleosecular variations over the last 3000 years recorded in annually laminated lake sediments from Finland. This correlation made it possible to construct, for the late Holocene Gotland Deep sediments, a high-resolution time-scale with an estimated absolute accuracy of better than ±50 years. This new timescale made it possible to determine the mean annual rates of sedimentation with an unprecedented accuracy. The sedimentation rates were found to have varied considerably both in time (from 0.2 up to 4.3 mm/year) and space, indicative of the patchy nature of accumulation in the Gotland Deep during the past 3000 years.