CONFERENCEChanges of the palaeo-geographical conditions in the Lake Usma depression during the end of the Late Glacial and the Holocene
Ivars Strautnieks
University of Latvia, Faculty of Geography and Earth Sciences
Elina Deksne
University of Latvia, Faculty of Geography and Earth Sciences
Laimdota Kalnina
University of Latvia, Faculty of Geography and Earth Sciences
Aija Cerina
University of Latvia, Faculty of Geography and Earth Sciences
Andra Stube
University of Latvia, Faculty of Geography and Earth Sciences
DOI: 10.22364/fg.17.2
Keywords: relief, Košķēni Bay, loss on ignition, Moricsala, Viskūži Island
Abstract
Lake Usma occupies the lowest part of the Late Glacial glacio-depression at the Kursa Lowland (NW Latvia), where the Venta-Usma ice-dammed lake and the Baltic Ice Lake sediments have been accumulated. Geological and geo-morphological investigations have been carried out on the largest Lake Usma islands - Moricsala and Viskūži Island as well as at Košķēni Bay. Changes in palaeo-geographic conditions in the Lake Usma depression during the Holocene are evidenced by organogenic sediments from cores in Moricsala and Viskūži Island and in the lake bottom of Košķēni Bay. The loss on ignition analysis of these sediments has been carried out with the aim to determine changes of organic, mineral and carbonate matter proportions and the relative percentage in their composition, which together with macro-remain analysis data allow to gain better understanding about the character of the palaeogeographic conditions during the lake's development.