Sedimentstratigrafiska och paleohydrologiska undersökningar av Fönesjön och Kalvs Mosse inom Vombslätten, centrala Skåne

Abstract

This study constitutes a preliminary survey within the project "Lake and groundwater paleohydrology of the Vomb plain, southern Sweden, for quantitative paleoclimatic calibration". The aim of the study is to describe the Holocene sediment stratigraphy of the former lakes Fönesjön and Kalvsjön (Kalvs mosse), and furthermore to describe and date stratgraphical indications of climatically caused lake-level changes in the Early Holocene. The Vomb plain is a flat area situated in the south-central part of the province of Scania, South Sweden. It consists of glacifluvial deposits, mainly sand, which compose an important groundwater supply. Within the plain a number of lakes are situated, and these are entirely dependent on the supply of groundwater. The lake levels are strictly defined by the position of the water table and the groundwater flow in the surrounding permeable deposits. The two investigated lakes are kettle-holes, today completely filled with Holocene organic sediments. The stratigraphy is built up mainly by gyttja and algae gyttja with an increasing amount of minerogenic matter towards the bottom. In some places distinct layers of silt and sand occur in the lower part of the organic sediments. The Holocene sediments are resting on sand, silt, clay and clay-gyttja, deposited during the Late Weichselian. The methods used were determination of loss on ignition, pollen analysis and measurement of magnetic susceptibility. By these methods it was possible to demonstrate that some of the stratigraphical records probably were caused by climatic changes. The study was also compared with a paleohydrological reconstruction from Lake Bysjön, a nearby site which earlier has been thoroughly investigated, resulting in a detailed Holocene water-level curve. The present results show that a distinct lowering of the water table occured in the area during the zones PB and BO 1 in the Early Holocene. The water level then rose substantially during the zone BO 2, and remained high throughout the rest of the Holocene, however possibly with some minor fluctuations. The two former lakes included in this study seem to be suitable for further investigatiotls within the project, as the conditions are favourable for paleohydrological reconstructions

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