Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits
Determining the age of glacial and glaciofluvial deposits is necessary to better understand the deglaciation of northeastern Poland. Cosmogenic 36 Cl, accumulated in boulders and matrix, suggests that inheritance and erosion affect cosmogenic inventories and must be taken into account when calculati...
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ftjgq:oai:geojournals.pgi.gov.pl:article/7451 2024-09-15T18:06:08+00:00 Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits Dzierżek, Jan Zreda, Marek 2010-03-27 application/pdf https://gq.pgi.gov.pl/article/view/7451 eng eng Polish Geological Institute-National Research Institute https://gq.pgi.gov.pl/article/view/7451/6101 10.7306/gq.v51i2.7451.g6101 https://gq.pgi.gov.pl/article/view/7451 Geological Quarterly; Vol. 51 No. 2 (2007); 203-216 Geological Quarterly; Tom 51 Nr 2 (2007); 203-216 1641-7291 10.7306/gq.v51i2 Poland last glaciation cosmogenic 36 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2010 ftjgq https://doi.org/10.7306/gq.v51i2 2024-07-30T03:29:08Z Determining the age of glacial and glaciofluvial deposits is necessary to better understand the deglaciation of northeastern Poland. Cosmogenic 36 Cl, accumulated in boulders and matrix, suggests that inheritance and erosion affect cosmogenic inventories and must be taken into account when calculating exposure ages of landforms. A simple approach to detect and distinguish between the two effects, by comparing the inventories of 36 Cl in boulders and matrix, allows us to compute appropriate corrections to apparent (uncorrected) ages and to determine model (corrected) exposure ages of the deposits. Apparent cosmogenic 36 Cl ages fall in the range between 11 ky and 28 ky (1 ky = 1000 calibrated 36 Cl years), pointing, correctly, to the end of the last glaciation, and correlate with oxygen isotope stage 2 (OIS 2). Model ages of glacial and glaciofluvial deposits fall into one of three time intervals. The oldest erratics, 27-28 ky (Kruszki and Bachanowo 1), date the advance of the Weichselian ice sheet. They are older than the surrounding surfaces, which confirms the existence of nunataks during later phases of the last glaciation. The main belts of recessional moraines formed 19.7 ą 1.0 ky ago (Gremzdy Polskie) and 17.9 ą 1.3 ky ago (Łopuchowo 2 and Gulbieniszki), and the last ice melted 14.4 ą 1.0 ky ago (Łopuchowo 1). Erosional terraces in the Czarna Hańcza valley were formed 14.7 ą 0.9 ky ago (Bachanowo 2) and 14.4 ą 1.0 ky ago (Bachanowo 3), probably by the melt waters from the last ice in the area. Our results suggest that different parts of the southern margin of the Fennoscandian Ice Sheet advanced and retreated independently, supporting the idea that the deposits at the southern margin of the Scandinavian Ice Sheet are not synchronous. Article in Journal/Newspaper Fennoscandian Ice Sheet Geological Quarterly |
institution |
Open Polar |
collection |
Geological Quarterly |
op_collection_id |
ftjgq |
language |
English |
topic |
Poland last glaciation cosmogenic 36 |
spellingShingle |
Poland last glaciation cosmogenic 36 Dzierżek, Jan Zreda, Marek Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits |
topic_facet |
Poland last glaciation cosmogenic 36 |
description |
Determining the age of glacial and glaciofluvial deposits is necessary to better understand the deglaciation of northeastern Poland. Cosmogenic 36 Cl, accumulated in boulders and matrix, suggests that inheritance and erosion affect cosmogenic inventories and must be taken into account when calculating exposure ages of landforms. A simple approach to detect and distinguish between the two effects, by comparing the inventories of 36 Cl in boulders and matrix, allows us to compute appropriate corrections to apparent (uncorrected) ages and to determine model (corrected) exposure ages of the deposits. Apparent cosmogenic 36 Cl ages fall in the range between 11 ky and 28 ky (1 ky = 1000 calibrated 36 Cl years), pointing, correctly, to the end of the last glaciation, and correlate with oxygen isotope stage 2 (OIS 2). Model ages of glacial and glaciofluvial deposits fall into one of three time intervals. The oldest erratics, 27-28 ky (Kruszki and Bachanowo 1), date the advance of the Weichselian ice sheet. They are older than the surrounding surfaces, which confirms the existence of nunataks during later phases of the last glaciation. The main belts of recessional moraines formed 19.7 ą 1.0 ky ago (Gremzdy Polskie) and 17.9 ą 1.3 ky ago (Łopuchowo 2 and Gulbieniszki), and the last ice melted 14.4 ą 1.0 ky ago (Łopuchowo 1). Erosional terraces in the Czarna Hańcza valley were formed 14.7 ą 0.9 ky ago (Bachanowo 2) and 14.4 ą 1.0 ky ago (Bachanowo 3), probably by the melt waters from the last ice in the area. Our results suggest that different parts of the southern margin of the Fennoscandian Ice Sheet advanced and retreated independently, supporting the idea that the deposits at the southern margin of the Scandinavian Ice Sheet are not synchronous. |
format |
Article in Journal/Newspaper |
author |
Dzierżek, Jan Zreda, Marek |
author_facet |
Dzierżek, Jan Zreda, Marek |
author_sort |
Dzierżek, Jan |
title |
Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits |
title_short |
Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits |
title_full |
Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits |
title_fullStr |
Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits |
title_full_unstemmed |
Timing and style of deglaciation of northeastern Poland from cosmogenic 36 Cl dating of glacial and glaciofluvial deposits |
title_sort |
timing and style of deglaciation of northeastern poland from cosmogenic 36 cl dating of glacial and glaciofluvial deposits |
publisher |
Polish Geological Institute-National Research Institute |
publishDate |
2010 |
url |
https://gq.pgi.gov.pl/article/view/7451 |
genre |
Fennoscandian Ice Sheet |
genre_facet |
Fennoscandian Ice Sheet |
op_source |
Geological Quarterly; Vol. 51 No. 2 (2007); 203-216 Geological Quarterly; Tom 51 Nr 2 (2007); 203-216 1641-7291 10.7306/gq.v51i2 |
op_relation |
https://gq.pgi.gov.pl/article/view/7451/6101 10.7306/gq.v51i2.7451.g6101 https://gq.pgi.gov.pl/article/view/7451 |
op_doi |
https://doi.org/10.7306/gq.v51i2 |
_version_ |
1810443635481640960 |