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TitleRefining the ice flow chronology and subglacial dynamics across the migrating Labrador Divide of the Laurentide Ice Sheet with age constraints on deglaciation
AuthorRice, J MORCID logo; Ross, MORCID logo; Paulen, R CORCID logo; Kelley, S E; Briner, J P; Neudorf, C M; Lian, O B
SourceJournal of Quaternary Science vol. 34, 2019 p. 1-17, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20180338
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
NTS13; 14C; 14D; 23A; 23B; 23C; 23F; 23G; 23H; 23I; 23J; 23K; 23N; 23O; 23P; 24A; 24B; 24C
AreaLac des Goélands; Caniapiscau Reservoir; Smallwood Reservoir; Rivière De Pas; George River
Lat/Long WENS -70.0000 -57.0000 57.0000 52.0000
Subjectssurficial geology/geomorphology; geochronology; geophysics; Science and Technology; Nature and Environment; glacial history; glaciation; Wisconsinian glacial stage; ice sheets; ice flow; ice margins; deglaciation; ice retreat; radiometric dating; isotopes; beryllium; glacial deposits; glacial features; glacial landforms; glacial striations; outwash; sands; erratics; eskers; tills; silts; meltwater channels; glacial lakes; beach ridges; remote sensing; photogrammetric techniques; airphoto interpretation; satellite imagery; radar methods; field work; bedrock geology; Laurentide Ice Sheet; Labrador Ice Divide; Ungava Bay Ice Stream; Last Glacial Maximum; Glacial Lake Naskaupi; De Pas Batholith; ice divides; ice streams; ice-flow directions; glaciolacustrine beach sediments; streamlined tills; till veneer; Phanerozoic; Cenozoic; Quaternary
Illustrationsgeoscientific sketch maps; location maps; tables; photographs; profiles; digital elevation models; plots
ProgramGEM2: Geo-mapping for Energy and Minerals Hudson/Ungava, Northeastern Quebec-Labrador, surficial geology
Released2019 09 03
AbstractThe Laurentide Ice Sheet was characterized by a dynamic polythermal base. However, important data and knowledge gaps have led to contrasting reconstructions in areas such as the Labrador Ice Divide. In this study, detailed fieldwork was conducted at the southeastern edge of a major landform boundary to resolve the relative ice flow chronology and constrain the evolution of the subglacial dynamics, including the migration and collapse of the Labrador Ice Divide. Surficial mapping and analysis of 94 outcrop-scale ice flow indicators were used to develop a relative ice flow chronology. 10Be exposure ages were used with optical ages to confine the timing of deglaciation within the study area. Four phases of ice flow were identified. Flow 1 was a northeasterly ice flow preserved under non-erosive subglacial conditions associated with the development of an ice divide. Flow 2 was a northwest ice flow, which we correlate to the Ungava Bay Ice Stream and led to a westward migration of the ice divide, preserving Flow 2 features and resulting in Flow 3's eastward-trending indicators. Flow 4 is limited to sparse fine striations within and around the regional uplands. The new optical ages and 10Be exposure ages add to the regional geochronology dataset, which further constrains the timing of ice margin retreat in the area to around 8.0 ka.
Summary(Plain Language Summary, not published)
This is a scientific journal paper on the ice flow chronology results from the GEM2 Core Zone Surficial Activity. This paper summarizes field observations with analytical results to resolve discrepancies in the scientific literature on the timing and chronology of ice flow and retreat from the dispersal centre of the Laurentide Ice Sheet. This research is in support of Jessey Rice's PhD thesis.

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