Geological development of the Zebrus-Svēte depression during the Late Glacial and the Holocene

Ivars Strautnieks

University of Latvia

Laimdota Kalnina

University of Latvia

Aija Cerina

University of Latvia

Eliza Platpire

Environment State Bureau of the Republic of Latvia, Environmental Impact Assessment Division

Peteris Danilevics

Latvian Environment, Geology and Meteorology Centre

Arta Glazere

University of Latvia

Ineta Grine

University of Latvia

DOI: 10.22364/fg.20.2.2

Keywords: Eastern Kursa upland, marginal formations, lakes, gyttja, peat

Abstract

The research area, the Zebrus–Svēte depression, is located in the southern part of the Eastern Kursa Upland in western Latvia and is one of many glaciodepressions of similar size and shape characteristic of this upland. All the glaciodepressions are bounded by glacial marginal formations, with their characteristic glacigenic landforms and glaciotectonic structures, which are additionally complicated by the formation of glaciolacustrine sediments. To get an understanding of the geological development and developmental stages of this depression, this study also compiles and clarifies information on the positive landforms around the glaciodepression. Nowadays the largest part of the glaciodepression is occupied by two separate lakes: Lake Zebrus and Lake Svēte. Studies of the depression relief isolines, as well as Lidar data and sediment composition characteristics, it can be concluded that at the end of the Late Glacial, there was a large single lake of glacial origin in the depression, which gradually divided into two separate lakes due to a level decrease. On the elevated belt between the two lakes, sediments – gyttja, silt and carbonatic clay – were covered by the low decomposed peat, and Elku Mire developed.