Late Quaternary lithofacies, provenance, and depositional environments (∼ 12-30 cal ka), north and south of the Denmark Strait

This paper describes the lithofacies and chronology of cores from north and south of the Denmark Strait for a period when ice sheets flanked both sides of the strait. A wide range of sediments have been recovered indicating a complex of depositional processes. JM96-1229GGC1 (1047 m water depth) is from the base of the NW Iceland slope at the southern edge of the Blosseville Basin, whereas JM96-1226GGC4 retrieved sediments south of the sill in 1519 m of water. Additional information is based on JM96-1220GGC2 and 1221GGC2 which were recovered from the upper W. Iceland slope at similar to500 m water depth below the Latra Moraine, of possible Last Glacial Maximum age, and upslope of JM96-1226. AMS C-14 dates indicate that JM96-1226 and -1229 span the last 10 to 27-32 ka BP whereas JM96-1220 and -1221 recovered sediments dated between ca. 8 and 18 ka BP. Closely-spaced radiocarbon dates on JM96-1229 indicate an erosional hiatus of similar to7 ky between 12 and 19 cal ka. Lithofacies descriptions are based on visual descriptions and X-radiographs. JM96-1229 consists of fine-grained sediments, sometimes graded, with scattered ice-rafted debris, whereas JM96-1226 consists largely of beds of matrix supported diamicton. Provenance indicators (mass magnetic susceptibility and geochemistry) for JM96-1229 support the delivery of sediments from NW Iceland, but there is a substantial difference in these properties between sediments from the W. Iceland upper slope and the sediments in JM96-1226 south of the Denmark Strait. This indicates that the diamictons on the floor of the strait did not derive entirely from the Iceland Ice Sheet and adjacent upper slope. The general absence of sediments < 12 cal ka on the slopes and floor of the Denmark Strait indicates that Denmark Strait Overflow Waters inhibited sediment accumulation during the Holocene. Between ca. 12 and 30 cal ka, however, a combination of more proximal sediment sources (ice sheets) and reduced thermohaline activity resulted in the accumulation of sediments on the slopes and basin floors. (C) 2003 Elsevier Science B.V. All rights reserved.