Sedimentary cover in former South-East Lithuania glaciolacustrine basin and its influence for groundwater infiltration

Abstract

The emergence of periglacial lakes in the territory of Lithuanian was conditioned by recessions and oscillations of the Baltija stage of Nemunas glacial. The slow recession of the glacier edge affected the evolution and drainage of the basins. Establishment of the drainage levels and analysis of the sections of glaciolacustrine sediments allows revealing their relationships with the recession phases of degrading glacier. The last stage of East and South Lithuanian glaciolacustrine basins – full drainage – was very important in their evolution. The intensity of glaciolacustrine drainage could be slow or cataclysmic. At one time in Late Glacial (Weichselian) existed seven large glaciolacustrin bassins. The oldest (about 130 ka) occupied glaciodepresions between Neris Middlestream, Vilnia and Dainava icetongues. Small and shallow basins were in high level: the eastern basin which affluent by Neris Middlestream and Vilnia ice-tongues shoreline was fixed in 220 m (Ašmena, in Belarus) and western basin which affluent by Vilnia and Dainava ice-tongues – in 200 m about middle sea level (ASL). In next stage (17–19 ka) cascade of glaciolacustrin basin existed in East Lithuania. The highest level basins had in north part and lowest – in south: Žeimena glaciolacustrine basin was in 155–160 m ASL, the Labanoras – 150–155, the Vilnia – 140–145 m, the Merkys Middlestream – 135 m, the Dubiciai – 125, the Biebrza (in Poland) – 110 m ASL. In central parts of former glaciolacustrine basins accumulated clay and loam, in peripherial parts – gravel, sand and silt. The granulometric composition of sediment layers determined infiltration conditions of recent surface-water. The goal of this article – evaluate infiltration condition and amount of surface-water in central and peripheral parts of different former glaciolacustrine basins.