Late Quaternary history around Nioghalvfjerdsfjorden and Jøkelbugten, North-East Greenland

Abstract

Nioghalvfjerdsfjorden in North-East Greenland is at present covered by a oating glacier. Raised marine deposits in the surrounding area contain shells of marine molluscs, bones of marine mammals and pieces of driftwood. A fairly systematic sampling of such material has been conducted, followed by extensive radiocarbon dating. We suggest that the Greenland ice sheet extended onto the shelf offshore North-East Greenland during isotope stage 2, perhaps even reaching the shelf break. During the subsequent recession of the ice sheet, the entrance of Nioghalvfjerdsfjorden had become ice-free by 9.7 cal. ka BP. The recession culminated between 7.7 and 4.5 cal. ka BP, during which time the fjord was glacier-free along its entire 80 km length. No dates younger than 4.5 cal. ka BP are available on marine material from the fjord, and it seems probable that the fjord has been continuously covered by the oating glacier since this time. The maximum glaciation was attained around AD 1900, after which thinning and recession took place. The marine limit increases from c. 40 m above sea level near the present margin of the Inland Ice to c. 65 m above sea level at the outer coast. These gures t into the regional pattern of the marine limit for areas both to the south and north. The marine fauna comprise two bivalves, Macoma calcarea and Serripes groenlandicus , that may represent a southern element present during the Holocene temperature optimum. Remains of three taxa of southern extralimital terrestrial and limnic plants were dated to 5.1 cal. ka BP, and remains of another extralimital plant were dated to 8.8 and 8.5 cal. ka BP. The known Holocene time ranges of the willow Salix arctica and the lemming Dicrostonyx torquatus have been extended back to 8.8 and 6.4 cal. ka BP, respectively, providing minimum dates for their immigration to Greenland.

Chronology of the last recession of the Greenland Ice Sheet

“…Thus in north east Greenland we feel inclined to place the Last Glacial Maximum off Nioghalvfjerdsfjorden at the continental shelf edge. In this context it may be mentioned that a small island was discovered recently on the shallow shelf off Nioghalvfjerdsfjorden (Bennike and Weidick, 2001). On this island, a small local ice cap occurs, and one can speculate that if local ice built up on the shelf, it might become confluent with the Greenland Ice Sheet.…”

“…1), whereas the inner part of the fjord was deglaciated prior to 7.7 cal. kyr BP, corresponding to a mean recession rate of 30-40 m yr −1 (Bennike and Weidick, 2001). The deglaciation of the outer part of the fjord is late compared with other outer coast sites of Greenland, which may result from the fact that the shelf is unusually broad.…”

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

“…Though earlier studies have suggested a deglaciation age of 11.7 to 10.1 ka (Bennike and Weidick, 2001;Bennike et al, 2008), the results of this investigation indicate that the Zackenberg lowlands may have been ice-free as early as 13 to 11 ka (Table 2;Figs. 7 and 8).…”

A 10 400-Year-Old Bowhead Whale (<i>Balaena mysticetus</i>) Skull from Ellef Ringnes Island, Nunavut: Implications for Sea-Ice Conditions in High Arctic Canada at the End of the Last Glaciation

“…Distribution of glacial ice is adapted from Dyke et al (2002) and England et al (2006). Arctic Ocean, although the oldest whale skeleton currently reported on northern Greenland is 1.2 ka younger than the bowhead whale described in this paper (Vibe, 1967;Bennike, 1987;Bennike and Weidick, 2001). Nevertheless, glaciological evidence from northern Greenland suggests that prior to the inception of a local ice cap at ~7.2 ka BP, the Hans tausen Plateau was ice-free during the early Holocene (Landvik et al, 2001; Fig.…”