The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution
Recent three-dimensional mapping investigations in southern Simcoe County, Ontario, allow refinement of the existing regional stratigraphic framework. Analysis of 25 continuously cored boreholes has revealed a complex but consistent sediment succession that provides a record of the last two glacial...
Published in: | Canadian Journal of Earth Sciences |
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crcansciencepubl:10.1139/cjes-2016-0160 2024-06-23T07:53:49+00:00 The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution Mulligan, Riley P.M. Bajc, Andy F. 2018 http://dx.doi.org/10.1139/cjes-2016-0160 http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2016-0160 http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2016-0160 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 55, issue 7, page 709-729 ISSN 0008-4077 1480-3313 journal-article 2018 crcansciencepubl https://doi.org/10.1139/cjes-2016-0160 2024-06-13T04:10:50Z Recent three-dimensional mapping investigations in southern Simcoe County, Ontario, allow refinement of the existing regional stratigraphic framework. Analysis of 25 continuously cored boreholes has revealed a complex but consistent sediment succession that provides a record of the last two glacial cycles (Marine Isotope Stages 1–6). Five stratigraphic units (SU1–SU5) comprise the pre-Late Wisconsin record. The stratigraphy is floored by a presumed Illinoian glacial complex consisting of a lower, coarse-grained till (SU1), locally overlain by stratified glaciolacustrine and glaciofluvial sediments (SU2), but more commonly capped by a stone-poor, fine-grained till (SU3) of the Georgian Bay lobe. A widespread subaerial unconformity developed on the upper surface of SU3 contains organic-bearing, nonglacial deposits (SU4) ranging between 54 800 ± 3000 years BP (considered beyond the limits of radiocarbon dating) and 37 450 ± 590 14 C years BP. SU4 is abruptly overlain by a thick succession of rhythmically laminated lacustrine muds graded upwards into glaciolacustrine silts and clays interrupted by regionally continuous sand bodies (SU5). The succession is capped (and locally truncated) by Late Wisconsin Newmarket Till. The sedimentary record of southern Simcoe County is correlated with other well-studied reference sections in southern Ontario and contains information that informs reconstructions of former ice extents in the lower Great Lakes region following the Illinoian glaciation. Several sediment units host aquifers, but limited thickness and spatial extent, as well as issues with naturally occurring dissolved gases and solids, restrict their use for groundwater supply. Article in Journal/Newspaper Ice Sheet Canadian Science Publishing Canadian Journal of Earth Sciences 55 7 709 729 |
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Canadian Science Publishing |
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crcansciencepubl |
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English |
description |
Recent three-dimensional mapping investigations in southern Simcoe County, Ontario, allow refinement of the existing regional stratigraphic framework. Analysis of 25 continuously cored boreholes has revealed a complex but consistent sediment succession that provides a record of the last two glacial cycles (Marine Isotope Stages 1–6). Five stratigraphic units (SU1–SU5) comprise the pre-Late Wisconsin record. The stratigraphy is floored by a presumed Illinoian glacial complex consisting of a lower, coarse-grained till (SU1), locally overlain by stratified glaciolacustrine and glaciofluvial sediments (SU2), but more commonly capped by a stone-poor, fine-grained till (SU3) of the Georgian Bay lobe. A widespread subaerial unconformity developed on the upper surface of SU3 contains organic-bearing, nonglacial deposits (SU4) ranging between 54 800 ± 3000 years BP (considered beyond the limits of radiocarbon dating) and 37 450 ± 590 14 C years BP. SU4 is abruptly overlain by a thick succession of rhythmically laminated lacustrine muds graded upwards into glaciolacustrine silts and clays interrupted by regionally continuous sand bodies (SU5). The succession is capped (and locally truncated) by Late Wisconsin Newmarket Till. The sedimentary record of southern Simcoe County is correlated with other well-studied reference sections in southern Ontario and contains information that informs reconstructions of former ice extents in the lower Great Lakes region following the Illinoian glaciation. Several sediment units host aquifers, but limited thickness and spatial extent, as well as issues with naturally occurring dissolved gases and solids, restrict their use for groundwater supply. |
format |
Article in Journal/Newspaper |
author |
Mulligan, Riley P.M. Bajc, Andy F. |
spellingShingle |
Mulligan, Riley P.M. Bajc, Andy F. The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution |
author_facet |
Mulligan, Riley P.M. Bajc, Andy F. |
author_sort |
Mulligan, Riley P.M. |
title |
The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution |
title_short |
The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution |
title_full |
The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution |
title_fullStr |
The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution |
title_full_unstemmed |
The pre-Late Wisconsin stratigraphy of southern Simcoe County, Ontario: implications for ice sheet buildup, decay, and Great Lakes drainage evolution |
title_sort |
pre-late wisconsin stratigraphy of southern simcoe county, ontario: implications for ice sheet buildup, decay, and great lakes drainage evolution |
publisher |
Canadian Science Publishing |
publishDate |
2018 |
url |
http://dx.doi.org/10.1139/cjes-2016-0160 http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2016-0160 http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2016-0160 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Canadian Journal of Earth Sciences volume 55, issue 7, page 709-729 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/cjes-2016-0160 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
55 |
container_issue |
7 |
container_start_page |
709 |
op_container_end_page |
729 |
_version_ |
1802645661896671232 |