Abstract

A high-resolution rock magnetic study of a Late Pleistocene core from the Labrador Sea, north of the Eirik Ridge on the Greenland rise, reveals three main features in the downcore variation of the rock magnetic parameters. Two are at the glacial–interglacial transitions (i.e., isotope stages 6–5e and 2–1), showing magnetic grain-size coarsening and increased magnetic concentration and accumulation. The magnetic grain-size coarsening and increased magnetic concentration associated with 6–5e transition and continuing into substage 5e are related to climatic influences. The magnetic grain-size coarsening and increased magnetic concentration and accumulation at the 2–1 transition appear to be climate related, although increased tephra concentrations may perturbate the record during this interval. Previous studies in this region have connected the coarsening of magnetic grain size during transitions to current winnowing of the finer fraction during interglacial conditions. The interpretation of the present study is that the coarsening is primarily due to increased detrital deposition related to ice retreat and the associated melt-water flux from southern Greenland. The third magnetic feature corresponds to the initial part of stage 2 where there is a distinct interval of higher coercivity. This high coercivity interval has no obvious correlation to climate change, but appears to be related to the increased preservation of ultrafine single domain ferrimagnetic material due to a lack of reduction diagenesis within this interval. The preservation of oxic conditions within this interval is indicated by a color change within the sediments.

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