Palaeosecular variation of the Earth's magnetic field during the last 10000 years based on the annually laminated sediment of Lake Nautäjarvi, central Finland

Abstract

A palaeomagnetic study of the Lake Nautajärvi sediment sequence in central Finland demonstrates that varved lake sediments can provideregionally applicable secular variations curves for Holocene stratigraphic correlation and age control. Based on x-ray radiography and digital image analysis techniques we constructed an inherent and continuous varve chronology for the Lake Nautajärvi varve sequence, which covers nearly 10000 years with an estimated counting error of less than ±1% and a mean sedimentation rate of 0.66 mm yr-1. We reconstructed a record of the palaeomagnetic secular variation (PSV) of the Earth's magnetic field in this nearly 7 m long section of clastic-organic varves. Mineral magnetic measurements indicated that pseudosingle-domain magnetite is the major carrier of the remanence. PSV shows many of the familiar features of declination and inclination that have previously been recorded in northern Europe. In addition, the Lake Nautajärvi record contains a continuous record of relative palaeointensity.