The mineral and isotopic signatures of glacially eroded sediments exported from Hudson Strait to the Labrador Sea during Hudson Strait Heinrich events H0 to H4

Abstract

The sediment signature of glacial erosion products exported from Hudson Strait to the Labrador Sea during Hudson Strait Heinrich (HS-H) events is evaluated using four distinct proxies: paired δ¹⁸Ο and δ¹³C data on the carbonate fraction, εNd and U–Pb isotopes in the silicate fraction, the mineral composition of the <2 mm bulk sediment fraction, and the lithologic composition of the >2 mm granules. Most detrital carbonate was eroded from Ordovician limestones on the floor of Hudson Strait. Silicate components were derived largely from Paleoproterozoic metamorphic and igneous bedrock, mostly on southern Baffin Island. A five-component sediment unmixing model shows that HS-H sediments were predominantly from Hudson Strait, whereas intervening sediment in the SW Labrador Sea has a predominant signature from Labrador but includes some detrital carbonate. Carbonate derived from the Western Basin and red sandstone granules from Keewatin are most abundant in the early part of HS-H 1, 2, and 4. Sediment budgets imply 10–15 m deepening of Hudson Strait over the last glacial cycle. The magnitude and longevity of detrital carbonate transport by icebergs during HS-H events require the inmixing of debris throughout the entire ice stream as it crossed the Abloviak sill.