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| Titel |
Holocene ice-ocean interactions: Køge Bugt, southeast Greenland |
| VerfasserIn |
Laurence M. Dyke, Camilla S. Andresen, Anna L. C. Hughes, Marit-Solveig Seidenkrantz, John F. Hiemstra, Tavi Murray, David A. Sutherland, Anders A. Bjørk, Hui Jiang, Longbin Shah |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128321
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| Publikation (Nr.) |
 EGU/EGU2016-8303.pdf |
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| Zusammenfassung |
| We present results from a 174 cm marine sediment core collected from Køge Bugt (Ikeq) in
central southeast Greenland. An age model was constructed from five 14C dates and five
210Pb determinations; this demonstrates that the core is composed of sediments that were
deposited without interruption over the last ∼9.1 cal. ka. Holocene oceanographic
conditions were reconstructed from measurements of the sortable silt mean and
from benthic foraminifera assemblage data. Assessment of the sortable silt data
demonstrates that they provide a valuable proxy for reconstructing palaeo-current vigour in
marine environments dominated by iceberg-rafted debris (IRD) sedimentation.
Holocene oceanic conditions in Køge Bugt were characterised by a tripartite history.
Warm oceanic conditions occurred in the early-Holocene, this was accompanied
by enhanced current-sorting of silt particles; we attribute this to incursion of the
core waters of the Irminger Current in Køge Bugt. A period of cooling occurred
during the mid-Holocene, this was followed by the establishment of cold, Polar
oceanic conditions in the late-Holocene. Holocene glacier activity in Køge Bugt was
reconstructed from measures of IRD abundance. We argue that coarse sediment in the
core was derived exclusively from icebergs that calved from local outlet glaciers.
Consequently, continuous IRD sedimentation demonstrates that glaciers in Køge Bugt
remained in tidewater settings throughout the last 9.1 ka. Bed topography data
show that the glacial troughs inland of the present-day ice margin are small (≤5 km
— Morlighem et al., 2014). Consequently, glaciers cannot have retreated more
than 5 km at any point in the record; this is despite climatic and oceanographic
conditions during the early-Holocene that were at least as warm as the present-day. This
behaviour is attributed to the specific geometry of the area. The glaciers that drain into
Køge Bugt flow over relatively steep beds; this allows them to achieve new stable
configurations quickly during phases of retreat. Finally, we suggest that the specific
physiography of Køge Bugt will restrict the retreat of large outlet glaciers here in
future. It is likely that these glaciers will remain in tidewater settings, at least in the
short-term, despite the predicted continuation of climatic and oceanic warming. |
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