Late Weichselian and Holocene Glacimarine Sedimentation and Environments in Kejser Franz Josephs Fjord and On The Adjacent Continental Margin, East Greenland
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The study outlines the glacimarine sedimentation patters and processes and environments in the Kejser Franz Josephs Fjord and on the adjacent continental margin of East Greenland during the Late Weichselian and Holocene.
A variety of techniques are adpoted in this study in order to address the objectives outlined previously. The study is based on a suite of 8 cores from the, mid to outer region of Kejser Franz Josephs Fjord, and the continental shelf and slope. Core analyses included i) logging (core and x-radiographs), ii) determination of grain size distribution, iceberg rafted debris and physical properties (water content, porosity, grain density), iii) determination of stable oxygen and carbon isotopes, iv) radiocarbon dating, and v) calculation of sedimentation and accumulation rates. Additionaly, acoustic data is incorporated into the study to place the sediment cores within a regional context in terms of the sedimentation patterns and processed throughout the study area.
The sedimentary record within the study dates back to the Late Weichselian glaciation. The record is confined to the continental slope and partly the continental shelf. The nature, extend and mechanisms of ice advance during the Late
Weichselian glaciation could not be determined in this study. The upper continental slope is characterised by iceberg sedimentation with additional contribution from distal remnant of meltwater outflows escaping from East Greenland,
sea ice rafting and pelagic settling. Mass wasting is recognised by the prescence of debris flows, which are derived from the rapid and unstable build-up of large volumes of glacigenic sediment. Mass wasting events are intermittent,
vary from small scale to large scale., and are derived from local slope regions. The mid to lower continental slope are characterised by rain out and suspension settling punctuated by intermittent sediment gravity flows. Sea ice
conditions during the Late Weichselian are extended resulting in reduced ventialtion of ocean surface waters and decreased exchange of CO
The onset of the Late Weichselian deglaciation is dated to occur after 15,250 yr BP. Degalciation is recognised by a rapid depletion of oxygen isotopes to very light values, indicating the massive discahrge of meltwater to the oceans
in response to the decay of the Greenland Ice Sheet. The meltwater pulse culminated at 13,020 yr BP on the continental slope and sometime between 10,000 - 13,010 yr BP on the continental shelf. The subsequent stratification of ocean
surface waters leads to the reduced ventilation of ocean surgace waters and decreased exchange of CO
The Younger Dryas Stadial is poorly represented in the sedimentary record of this study relating to low sedimentation rates and the low resolution of the sedimentary during this interval. Isotopic records indicate extended sea ice
conditions over the contintental slope, resulting in reduced ventilation of ocean surface waters and decreased exchange of CO
The onset of the post Younger Dryas deglaciation occurs soon after 10,000 yr BP and is marked by a meltwater pulse that influences the fjord and inner continental shelf. The meltwater discharge culminated at 9,540 yr BP on the inner
contintental shelf and sometime before 7,440 yr BP in the outer fjord. The meltwaters are produced from the final retreat of the glacier-ice of the Greenland Ice Sheet to present day positions. The presence of laminated mud facies
and iceberg rafted debris (sandy mud diamicton and mud with dropstones) indicate that ice mass loss is through ablation and iceberg calving. The subsequent stratification of ocean surface waters leads to the reduced ventilation
of ocean surface waters and decreased exchange of CO
The Holocene is characterised by decreased sea ice conditions leading to increased ventilation of ocean/fjord surface waters and the increased exchange of CO