Abstract
As part of a multi-disciplinary study of maar lake sediments, magnetic properties of some 3000 samples from two long cores extracted from the bottom sediments of Lago Grande di Monticchio located in southern Italy have been measured and the results connected with lithological, palynological and geochemical data obtained from the same cores. A time-scale, based on microlaminations, radiocarbon and Ar Ar age determinations (see companion papers in this special issue of Quaternary Science Reviews) dates the base of the longer 51 m core at about 76 ka before the present. The strengths of anhysteretic remanence, saturation isothermal remanence and susceptibility are highly sensitive to the contrast between stadial and interstadial conditions, showing almost flip-flop transitions at Oxygen Isotope Stage 5a/4 and Stage 2/1 boundaries as previously observed for Lac du Bouchet, another maar lake site located in the Haute Loire Province of France. On the other hand, these laboratory installed magnetizations vary smoothly through sediment deposited during stadials. A prolonged period of heavy (modelled) precipitation starting at ∼25 ka BP coincides with a marked decrease in measured magnetic intensities possibly associated with the consequent increase in lake level and lake water chemistry. The natural remanent magnetization is dominated by climatic and environmental influences: nevertheless a weak signal attributed to variations in the palaeointensity of the geomagnetic field has been isolated, and it shows good broad-scale agreement with that previously reported for Lac du Bouchet.
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