Cable, Stefanie; Christiansen, Hanne H; Westergaard-Nielsen, Andreas; Kroon, Aart; Elberling, Bo (2017): Geomorphological and geocryological maps of the Zackenberg Valley, NE Greenland (ArCGIS Map Package). PANGAEA, https://doi.org/10.1594/PANGAEA.883484, Supplement to: Cable, S et al. (in press): Geomorphological and cryostratigraphical analyses of the Zackenberg Valley, NE Greenland and significance of Holocene alluvial fans. Geomorphology, https://doi.org/10.1016/j.geomorph.2017.11.003
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In High Arctic northern Greenland, future responses to climatic changes are poorly understood on a landscape scale. Here, we present a study of the geomorphology and cryostratigraphy in the Zackenberg Valley in NE Greenland (74°N) containing a geomorphological map and a simplified geocryological map, combined with analyses of 13 permafrost cores and two exposures. Cores from a solifluction sheet, alluvial fans, and an emerged delta were studied with regards to cryostructures, ice and total carbon contents, grain size distribution, and pore water electrical conductivity; and the samples were AMS 14C dated. The near-surface permafrost on slopes and alluvial fans is ice rich, as opposed to the ice-poor epigenetic permafrost in the emerged delta. Ground ice and carbon distribution are closely linked to sediment transport processes, which largely depend on lithology and topography. Holocene alluvial fans, covering 12% of the lowermost hillslopes, represent paleoenvironmental archives. During the contrasting climates of the Holocene, the alluvial fans continued to aggrade - through the warmer early Holocene Optimum, the colder late Holocene, and the following climate warming - and by 0.45 mm a- 1, on average. This is caused by three factors: sedimentation, ground ice aggradation, and vegetation growth and is reflected by AMS 14C dating and continuously alternating cryostructures. Highly variable sedimentation rates in space and time at the alluvial fans have been detected. This is also reflected by alternating lenticular and microlenticular cryostructures indicating syngenetic permafrost aggradation during sedimentation with suspended and organic-matrix cryostructures indicating quasi-syngenetic permafrost aggradation in response to vegetation growth in periods with reduced or no sedimentation. Over time, this causes organic matter to become buried, indicating that alluvial fans represent effective carbon sinks that have previously been overlooked.
Latitude: 74.473060 * Longitude: -20.552500
This ArCGIS Map Package has been created as part of the EU project 'Changing Permafrost in the Arctic and its Global Effects in the 21st Century' (PAGE21 project) and comprises the shapefiles of the gemorphological and geocryological maps of the Zackenberg Valley in NE Greenland published as Figures 2, 12 and S2 in Cable et al. (2017).
Principle Investigator: Stefanie Cable (firstname.lastname@example.org)