GEOSCAN Search Results: Fastlink

GEOSCAN Menu


TitleGlobal ice volume during MIS 3: substantial or insignificant?
AuthorHelmans, K; Väliranta, M; McMartin, I; Campbell, J E; Eskola, T; Sarala, P
SourceXIX INQUA Congress, abstracts; 2014 p. 1
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20140386
PublisherInternational Union for Quaternary Research
MeetingXIX INQUA Congress; Nagoya; JP; July 27 - August 2, 2015
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatpdf
Subjectspaleontology; surficial geology/geomorphology; ice sheets; ice retreat; ice movement; climate; glaciation; MIS 3; LGM
ProgramRae Province Project Management, GEM2: Geo-mapping for Energy and Minerals
AbstractIn contrast to the classic concept of extensive glaciation in the northern Hemisphere during MIS 3, recent studies on sediments from the central areas of the Fennoscandian (N Europe) and Laurentide (N America) ice sheets suggest a significantly reduced MIS 3 ice-cover. The study of long sediment sequences, detailed OSL dating, as well as 14C dating on carefully selected plant macrofossils, record mild climate conditions (with present-day summer temperatures) accompanied by large-scale deglaciation of the Fennoscandian Ice Sheet in early MIS 3 at ca. 55-50 kyr BP. Ice-free conditions with birch-dominated vegetation (including tree birch) persisted over large parts of Fennoscandia, possibly interrupted by glaciation, to at least ca. 35 kyr BP. Furthermore, detailed 14C dating of marine molluscs present as glacial erratics in streamlined till indicates that the north-western portion of Hudson Bay in N America may have been ice-free during MIS 3 for a minimum of some 7.5 kyr (from ca. 39 to 31.5 kyr BP). These studies question the relative large global ice volume estimates for MIS 3 based on the marine record (foraminifera oxygen isotope and coral-based sea-level records) and indicate rapid build-up of continental ice to LGM limits (MIS 2). The apparent absence of sub-continental size glaciation over N Europe and reduced ice-cover over N America during (or parts of) MIS 3 have large implications for e.g. climate modeling and studies on flora/fauna/human migrations, as well as the understanding of driving and feedback mechanisms for the high-amplitude, millennial-scale climate variability of MIS 3.
Summary(Plain Language Summary, not published)
Previously unknown ancient sediments located in the centres of past ice sheets in Scandinavia and Canada and dated to a time prior to the last continental glaciations were recently discovered and documented in northern Finland and central mainland Nunavut. These discoveries have great implications for the paleo-history of past glaciers and paleo-climate change, and provide new geological evidence for possible warming trends 30,000 to 50,000 years ago in the northern hemisphere. This work was conducted under the Melville Peninsula Project at the Geological Survey of Canada, as part of Natural Resources Canada's Geo-mapping for Energy and Minerals (GEM-1) Program.
GEOSCAN ID295725