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TitreDistribution, thickness and origin of Heinrich layer 3 in the Labrador Sea
AuteurRashid, H; Hesse, R; Piper, D J W
SourceEarth and Planetary Science Letters 205, 2003 p. 281-293,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 2003236
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'est
SNRC13I; 13O; 13P; 14C; 14F; 14K; 14L; 14M; 14N; 15C; 15D; 15E; 15F; 15K; 15L
Lat/Long OENS -62.0000 -48.0000 63.0000 54.0000
Sujetsmarges continentales, atlantique; marges continentales; Pléistocène; dépôts glaciaires; carottages par piston; carottes de sédiment marin; géologie marine; géologie des dépôts meubles/géomorphologie; Cénozoïque
Illustrationssketch maps; tables; stratigraphic sections; graphs
Résumé(disponible en anglais seulement)
The presence of Heinrich layer 3 (HL-3) in the northwest Labrador Sea has been debated in the literature. Calypso giant piston core MD99-2233, five new standard piston cores, and re-interpretation of 34 cores from previous cruises confirm the presence of HL-3 in the Labrador Sea. It is identified by high total carbonate concentration (up to 45%), an increase in coarse fraction content, and lighter d18O values in polar species planktonic foraminifer Neogloboquadrina pachyderma (left-coiling) as low as 3.1 per thousand. The age of HL-3 of ~27 ka was bracketed in the various cores by about 50 14C-accelerator mass spectrometer dates. Where it is present in ice-proximal regions, it consists of nepheloid-flow deposits at the base and mud turbidites at the top. The thickness of HL-3 varies between 4.8 m (proximal to Hudson Strait) and 0.9 m (distal), decreasing rapidly seaward. On the upper continental slope, HL-3 was too deeply buried to be sampled. Elsewhere, HL-3 is absent in some cores, probably due to slumping or erosion associated with sandy turbidity currents or debris flows.