Abstract
This paper presents the glacial stratigraphy and palaeoenvironmental evolution around Constable Bugt,
Johannes V. Jensen Land, located on the north coast of Greenland. This is a land of extreme climate: polar
desert conditions and a coast bound by a permanent sea ice cover. Our data covers the period from the
Last Glacial Maximum (LGM, 18e22 cal ka BP) into the Holocene. It records the history of a shelf-based
glaciation with ice flowing eastward along the coast as well as two local valley glacier advances from the
south during the Holocene. With ice on the coastal plain during the LGM, glaciolacustrine basins formed
in marginal positions and in ice-dammed valleys to the south into the mountainous area of Peary Land.
With the break-up of shelf-based ice there was a gradual marine inundation at which the marine limit
formed at w45 m a.s.l. This initial early Holocene ice advance from the south formed prominent valley
mouth moraines, especially in Sifs valley. Here, both glaciolacustrine and marine sediments were
remoulded and/or dislocated as thrust blocks into a moraine ridge spanning more than 1 km in width
and >60 m in height. Radiocarbon ages of sediments incorporated in this moraine, as well as from onlapping
sediments, suggest that the moraine formed between 9.6 and 6.3 cal ka BP. Based on 14C dating
results, the youngest ice advance phase can be narrowed down to 14C ages between w5.5e5.0 cal ka BP.
The recorded ice advances took place during the Holocene Thermal Maximum (HTM) for North
Greenland, the last one close to the beginning of the Neoglacial cooling. During the HTM we have
recorded a period of w2500 years during which the north coast of Greenland e as opposed to today e
experienced an absence to very restricted occurrence of land-fast or multi-year sea ice. This observation
can be explained by the altitudinal and temporal distribution of beach-ridge complexes that must have
formed by wave action and thus requiring at least partial open-water conditions. With a moisture source
at hand, we propose that this lead to enhanced precipitation in the near-coastal areas which, coupled to
documented HTM cold reversals, caused a lowered glaciation limit, and led to a positive mass balance
and subsequent ice advance.
Johannes V. Jensen Land, located on the north coast of Greenland. This is a land of extreme climate: polar
desert conditions and a coast bound by a permanent sea ice cover. Our data covers the period from the
Last Glacial Maximum (LGM, 18e22 cal ka BP) into the Holocene. It records the history of a shelf-based
glaciation with ice flowing eastward along the coast as well as two local valley glacier advances from the
south during the Holocene. With ice on the coastal plain during the LGM, glaciolacustrine basins formed
in marginal positions and in ice-dammed valleys to the south into the mountainous area of Peary Land.
With the break-up of shelf-based ice there was a gradual marine inundation at which the marine limit
formed at w45 m a.s.l. This initial early Holocene ice advance from the south formed prominent valley
mouth moraines, especially in Sifs valley. Here, both glaciolacustrine and marine sediments were
remoulded and/or dislocated as thrust blocks into a moraine ridge spanning more than 1 km in width
and >60 m in height. Radiocarbon ages of sediments incorporated in this moraine, as well as from onlapping
sediments, suggest that the moraine formed between 9.6 and 6.3 cal ka BP. Based on 14C dating
results, the youngest ice advance phase can be narrowed down to 14C ages between w5.5e5.0 cal ka BP.
The recorded ice advances took place during the Holocene Thermal Maximum (HTM) for North
Greenland, the last one close to the beginning of the Neoglacial cooling. During the HTM we have
recorded a period of w2500 years during which the north coast of Greenland e as opposed to today e
experienced an absence to very restricted occurrence of land-fast or multi-year sea ice. This observation
can be explained by the altitudinal and temporal distribution of beach-ridge complexes that must have
formed by wave action and thus requiring at least partial open-water conditions. With a moisture source
at hand, we propose that this lead to enhanced precipitation in the near-coastal areas which, coupled to
documented HTM cold reversals, caused a lowered glaciation limit, and led to a positive mass balance
and subsequent ice advance.
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | Quaternary Science Reviews |
| Vol/bind | 29 |
| Udgave nummer | 25-26 |
| Sider (fra-til) | 3379-3398 |
| Antal sider | 20 |
| ISSN | 0277-3791 |
| DOI | |
| Status | Udgivet - dec. 2010 |
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