Provenance of sediment in the Labrador Current: a record of hinterland glaciation over the past 125 ka

Abstract

ABSTRACTThe Labrador Current flows southward along the continental margin off eastern Canada and is the principal source of sediment to the outer continental margin areas where ice sheets did not cross the continental shelf. We present multi‐proxy mineralogical and geochemical records based principally on X‐ray diffraction and X‐ray fluorescence for core 2011031‐059 from northern Flemish Cap to determine changes in supply and hence to reconstruct provenance evolution during the last glacial cycle. The calcite to dolomite ratios in Heinrich layers ranged from 2 to 4, suggesting carbonate layers derived from Hudson Strait as early as Marine Isotope Stage (MIS) 5a–d. Mineral abundance shows three time‐dependent predominant sediment sources other than in Heinrich layers: (i) Baffin Bay shelves and adjacent land in MIS 5 and 1, with high Ca, Sr, kaolinite and feldspars and low clay minerals and calcite/dolomite ratios; (ii) Labrador in MIS 3, with low clays and grey color; and (iii) north‐east Newfoundland Shelf in MIS 2 and 4, with higher concentrations of clay minerals, red sandstones and transition elements. These results allow a reconstruction of principal ice streams supplying the north‐west Atlantic over the last full glacial cycle.