A record of Holocene climate in the mineral magnetic record of Alpine lakes: Sagistalsee and Hinterburgsee

The effect of climate variations on the magnetic properties of sediments fr om two small Alpine lakes in the Bernese Alps, Switzerland was investigated . Although relatively similar in water volume and general environment, Sagi stalsee and Hinterburgsee have different catchment vegetation and lithology due to their different elevation and geographic locations. The climatic si gnal in the mineral magnetic parameters of the sediments was validated and interpreted with the aid of palynological and geochemical data. The sedimen t age was determined with several accelerated mass spectrometry C-14 dates. The results from the different lakes compare well on a common time scale a nd show that the influence of local conditions on the magnetic record is ra ther small. A climatic influence on the mineral magnetism has been recogniz ed at both studied sites. This is interpreted as a consequence of the produ ction of an authigenic mineral with particularly uniform magnetic propertie s during the warmer stages and the influx of heterogeneous detrital magneti c minerals during the colder stages. The dearest climate record is found in sediments with no organic matter whereas the anoxic conditions found in hi ghly organic sediment can completely obliterate the climate signal recorded in the sediment magnetic properties. (C) 2001 Elsevier Science B.V. All ri ghts reserved.