Premium
Development, evolution and drainage of glacial Lake Naskaupi during the deglaciation of north‐central Quebec and Labrador
Author(s) -
DUBÉLOUBERT HUGO,
ROY MARTIN
Publication year - 2017
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2997
Subject(s) - deglaciation , geology , glacial lake , meltwater , shelf ice , glacial period , landform , physical geography , ice sheet , stage (stratigraphy) , drainage basin , hydrology (agriculture) , geomorphology , oceanography , cryosphere , ice stream , sea ice , paleontology , geography , geotechnical engineering , cartography
Deglaciation of north‐central Quebec and Labrador led to the development of large ice‐dammed lakes in river valleys surrounding Ungava Bay. These lakes are poorly understood due to uncertainties in the regional pattern of ice retreat. Lake Naskaupi occupied the George River valley where systematic mapping of glacial landforms and extensive elevation measurements of shorelines reveal a complex history characterized by multiple lake levels. Our reconstruction documents three well‐defined lake levels marking extensive lake stages. Additional lake levels are poorly developed and relate to short‐lived, transient lake stages. During its main stage (N2′), Lake Naskaupi consisted of two separate basins that evolved independently for some time. This configuration resulted from the persistence of cold‐based ice conditions during the deglaciation that caused the retreating ice margin to remain in the middle section of the river valley. The presence of this ice dam is supported by large‐scale outburst flood deposits that record the abrupt drainage of the southern Naskaupi basin. The magnitude of the elevation changes between the remaining lower lake levels suggests the occurrence of at least one other major drawdown before the final lake drainage. Reconstruction of the N2′ lake stage provides a minimum meltwater volume estimate for the lake.