{"title":"Glacial varves at the distal slope of Pandivere-Neva ice-recessional formations in western Estonia","authors":"P. Talviste, T. Hang, M. Kohv","doi":"10.17741/BGSF/84.1.001","DOIUrl":null,"url":null,"abstract":"The distribution and varve thickness data of Late Weichselian varved clay were analyzed to describe the proglacial sedimentary environment, ice recession and water-level changes in the Baltic Ice Lake at the distal position of Pandivere–Neva (13.5–13.1 ka BP) icerecessional formations in western Estonia. According to vertical changes in natural water content, fabric and varve thickness, four clay units were distinguished, reflecting a change in the sedimentary environment from ice-proximal to distal conditions. The varved clay complex is locally interrupted by a massive silty-clay unit, interpreted as an icedrift material during the stagnation of the glacier margin at the Pandivere–Neva line. Varve correlation gave a 294-year-long floating varve chronology. According to total varve thickness and the relation between thicknesses of seasonal layers, an about 130year period of ice-proximal conditions in the study area was followed by a rapid (within ca 20 years) change to more distal conditions. The presented varve chronology does not cover the entire period of proglacial conditions in the area, as all studied clay sections displayed an erosional discontinuity at the upper contact. In total, ca 4 m of selective post-sedimentary erosion of clay is attributed to wave erosion due to a water-level drop after the final drainage of the Baltic Ice Lake. It is concluded that the Yoldia Sea minimum level in the Pärnu area was 0 to –2 m a.s.l.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"10","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of the Geological Society of Finland","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.17741/BGSF/84.1.001","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 10
Abstract
The distribution and varve thickness data of Late Weichselian varved clay were analyzed to describe the proglacial sedimentary environment, ice recession and water-level changes in the Baltic Ice Lake at the distal position of Pandivere–Neva (13.5–13.1 ka BP) icerecessional formations in western Estonia. According to vertical changes in natural water content, fabric and varve thickness, four clay units were distinguished, reflecting a change in the sedimentary environment from ice-proximal to distal conditions. The varved clay complex is locally interrupted by a massive silty-clay unit, interpreted as an icedrift material during the stagnation of the glacier margin at the Pandivere–Neva line. Varve correlation gave a 294-year-long floating varve chronology. According to total varve thickness and the relation between thicknesses of seasonal layers, an about 130year period of ice-proximal conditions in the study area was followed by a rapid (within ca 20 years) change to more distal conditions. The presented varve chronology does not cover the entire period of proglacial conditions in the area, as all studied clay sections displayed an erosional discontinuity at the upper contact. In total, ca 4 m of selective post-sedimentary erosion of clay is attributed to wave erosion due to a water-level drop after the final drainage of the Baltic Ice Lake. It is concluded that the Yoldia Sea minimum level in the Pärnu area was 0 to –2 m a.s.l.
期刊介绍:
Bulletin of the Geological Society of Finland (BGSF) publishes research articles and short communications in all branches of geosciences. Contributions from outside Finland are welcome, provided that they contain material relevant to Finnish geology or are of general interest.