Late Quaternary history of the Kap Mackenzie area, northeast Greenland BERND WAGNER, OLE BENNIKE, HOLGER CREMER AND MARTIN KLUG BOREAS Wagner, B., Bennike, O., Cremer, H. & Klug, M. 2010 (July): Late Quaternary history of the Kap Mackenzie area, northeast Greenland. Boreas, Vol. 39, pp. 492–504. 10.1111/j.1502-3885.2010.00148.x. ISSN 0300-9483. The Kap Mackenzie area on the outer coast of northeast Greenland was glaciated during the last glacial stage, and pre-Holocene shell material was brought to the area. Dating of marine shells indicates that deglaciation occurred in the earliest Holocene, before 10 800 cal. a BP. The marine limit is around 53 m a.s.l. In the wake of the deglaciation, a glaciomarine fauna characterized the area, but after c. one millennium a more species-rich marine fauna took over. This fauna included Mytilus edulis and Mysella sovaliki, which do not live in the region at present; the latter is new to the Holocene fauna of northeast Greenland. The oldest M. edulis sample is dated to c. 9500 cal. a BP, which is the earliest date for the species from the region and indicates that the Holocene thermal maximum began earlier in the region than previously documented. This is supported by driftwood dated to c. 9650 cal. a BP, which is the earliest driftwood date so far from northeastern Greenland and implies that the coastal area was at least partly free of sea ice in summer. As indicated by former studies, the Storegga tsunami hit the Kap Mackenzie area at c. 8100 cal. a BP. Loon Lake, at 18 m a.s.l., was isolated from the sea at c. 6200 cal. a BP, which is distinctly later than expected from existing relative sea-level curves for the region. Bernd Wagner (e-mail: wagnerb@uni-koeln.de) and Martin Klug (e-mail: mklug@uni-koeln.de), Institute for Geology and Mineralogy, University of Cologne, Z ¨ ulpicher Strasse 49a, D-50674 Cologne, Germany; Ole Bennike (e-mail: obe@geus.dk), Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark; Holger Cremer (e-mail: holger.cremer@tno.nl), Netherlands Organization for Applied Scientific Research TNO – Geological Survey of the Netherlands, Princetonlaan 6, NL-3584 CB Utrecht, The Netherlands; received 20th November 2009, accepted 17th January 2010. The extent of glaciation in northeast Greenland during the Last Glacial Maximum (LGM) has been discussed for a long time. The find of pre-Holocene shell frag- ments in the Kap Mackenzie area (Funder & Hjort 1973) led to the erection of a glacial stade, the so-called Kap Mackenzie Stadial, during the Weichselian, when the Greenland Ice Sheet advanced. It has been sug- gested that large lowland areas remained ice-free during the Weichselian (Funder & Hjort 1973; Hjort 1981; Funder & Hansen 1996); however, this reconstruction was based mainly on geomorphological criteria. More recent data from the shelf offshore northeast Greenland suggest that the margin of the Greenland Ice Sheet ex- tended far out on the shelf, perhaps to the shelf edge during the LGM (Evans et al. 2008). Exposure age dating from Jameson Land implies that this lowland area was glaciated during the LGM (H˚akansson et al. 2009), indicating more extensive glaciation than for- merly suggested. Although there is a growing body of evidence con- cerning the Quaternary history of northeastern Green- land, and data on marine deposits, relative sea-level changes and the deglaciation chronology have been published (e.g. Jensen 1917; Noe-Nygaard 1932; Fun- der & Hjort 1973; Hjort 1973, 1979, 1981; Hjort & Funder 1974; Bj ¨orck et al. 1994a, b; Weidick et al. 1996; Wagner & Melles 2002; Bennike et al. 2008 and Cremer et al. 2008), only little information is available on the late Quaternary marine and littoral deposits of the Kap Mackenzie area. In addition to the description of pre- Holocene shell fragments (Funder & Hjort 1973), there exists a field report from an expedition to the Kap Mackenzie region in 2003 (Bennike et al. 2004). A sedi- ment core (Lz1116) recovered during this expedition from Loon Lake contains a distinct sand layer, which was interpreted as the first indication in Greenland of deposits from the Storegga tsunami at around 8100 cal. a BP (Wagner et al. 2007). Here we report on further laboratory work on the sediment core from Loon Lake and on work on samples from the raised marine depos- its in the vicinity of the lake. The data from the sedi- ment record and from the marine deposits provide new important information on the regional deglaciation history, the sea-level history and the climate history. Study area Kap Mackenzie is located on northeastern Geo- graphical Society Ø in northeastern Greenland. The region around Kap Mackenzie is bordered by Kejser Franz Joseph Fjord to the north and Cambridge Bugt to the southeast (Fig. 1). The topography in the vicinity of Kap Mackenzie is characterized by a slightly as- cending landscape to the central part of the island, where the highest mountains reach an elevation of 1700 m above sea level (a.s.l.). Several ridges with ele- vations of up to 100 m a.s.l. separate local depressions DOI 10.1111/j.1502-3885.2010.00148.x r 2010 The Authors, Journal compilation r 2010 The Boreas Collegium