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| Titel |
Glacimarine sedimentary processes and depositional environments in Disko Bay, West Greenland |
| VerfasserIn |
K. A. Hogan, J. A. Dowdeswell, C. O. Cofaigh |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070780
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| Zusammenfassung |
| A 3.5 kHz sub-bottom profiler survey in and around Disko Bay in 2009 penetrated significant
thicknesses of unconsolidated sediments. Given low modern sedimentation rates, these thick
sediment packages are inferred to be glacimarine deposits delivered during deglaciation from
the Last Glacial Maximum (LGM). Sediment thicknesses and volumes in three
glaciated areas, Disko Bay, southern Vaigat and Egedesminde Trough, are fully
constrained for the first time; however, the largest thicknesses (256 m) and volumes (c. 32
km3), and the widest variation in acoustic character was observed in Disko Bay
adjacent to the mouth of Jakobshavn Isfjord. Here we present acoustic profiles from
the study area (Disko Bay, the southern Vaigat, the Egedesminde Dyb trough),
interpret the acoustic stratigraphy in terms of deglacial sedimentary processes, and
present quantitative information on deglacial sediment volumes and fluxes. For the
palaeo-Jakobshavn ice stream, which is known to have stabilised at the fjord-entrance
sill, a sediment flux of 1.6-3.6 Ã 107m3 a-1 is estimated. Assuming a flux at the
upper end of this range for the Torssukatak fjord system requires the grounded ice
margin to be stable for c. 450 years during retreat in order produce the volume
of glacimarine sediments that we observe. The high sediment fluxes we calculate
suggest that meltwater was readily available at the base of the outlet glaciers during
deglaciation, even during periods of quasi-stability. Overall our results highlight
similarities in deglacial sedimentary processes across the study area, when the margins of
retreating glaciers supplied large volumes of sediment to the marine environment from
sediment-laden meltwater plumes and melting icebergs. However, it also highlights the
importance of local factors, such as bedrock morphology, on sedimentation patterns. |
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