Base de données de recherche des TNO

étiquettes: physical sciences, geology, glaciology, paleoclimatology, environmental change

Objectif(s): To understand and reconstruct past glacier extent and dynamics, past climates and ongoing sea level change, including submergence, on Banks and Prince Patrick Islands, through geological mapping and the dating of sea shells, sediment and boulders.

Description du projet: The researchers aim to understand and reconstruct the extent and dynamics of past glaciers, past climates and ongoing sea level change, including submergence, on Banks and Prince Patrick Islands, through geological mapping and the dating of sea shells, sediment and boulders. High latitude areas such as the Canadian High Arctic provide diverse records of past global changes and they are generally the first regions to be affected by climate variability. Hence, it is of prime importance to obtain more palaeoenvironmental data from these regions in order to have a better understanding of possible future climatic conditions. This project concerns the nature and style of past glaciations as well as the history of sea level and climatic changes in the western Canadian High Arctic. The researchers’ broad objective is to obtain a long-term palaeoclimatic record from glacial landforms and past (higher) sea levels. This will help to determine what climatic conditions favoured the build-up and removal of ice sheets in the western Arctic during the past ~30,000 years and place recent decreasing sea ice and glacier retreat in a broader context. Additionally, they will investigate past and present rates of sea level change, including rising sea level in the western Arctic affecting local communities. Researchers and equipment will be placed into field camps via Twin Otter aircraft and helicopter. One research team (Coulthard party) will operate out of a small field camp on Prince Patrick Island (Bloxsome Bay, 1 to 20 July), while the other research team (Lakeman party) will operate out of two small field camps on eastern Banks Island (2-30July). Transects will be conducted from these camps via helicopter (~10 days: from 10-20 July) and ATV (~20 days). Ancient shorelines, which are now far inland and above modern sea level, will be mapped and surveyed. Fossils, which are frequently observed on these shorelines and related raised marine sediments, will be collected and radiocarbon dated. These radiocarbon dates, in combination with the mapped and surveyed raised shorelines, will be used to calculate rates of sea level change in the past. Fossils include marine mollusk shells (most commonly Hiatella arctica) and driftwood. A small number of fossil mollusks will be collected from each site and only a few grams of driftwood will be sampled, collectively representing only a very small proportion of the existing fossil material that is widespread on the landscape. Sample locations will be surveyed and recorded using GPS receivers. Sample elevations will be determined using digital altimeters. Large boulders will be sampled for terrestrial cosmogenic nuclide dating. This entails sampling <1kg of rock from the upper surface of large boulders using a rock saw and chisel. Efforts will be made to ensure that the sampled surface is left in a natural appearing state. The principal investigator, Dr. England, will supply a summary of the research in plain language to be circulated amongst the surrounding communities (Sachs Harbour, Holman, and Cambridge Bay), and also make this information available to the Aurora Research Institute's library. Dr. England also intends to give lectures in the Natural Resources Technology Program at Aurora College in the fall of 2007. If possible, he will visit the community of Sachs Harbour in the fall of 2007 to share research results from the western Arctic. Fieldwork will be conducted from June 23 to August 11, 2007 from several, pertinent coastal sites on Prince Patrick Island (primarily near Bloxsome Bay camp; ~76°02.5’N 122°32.0’W; ~ 80km from Mould Bay and ~600km from Sachs Harbour) and eastern Banks Island (primarily near Johnson Point; ~72°45.17’N 118°30.0’W, and a second camp 60-80km to the west, exact location TBD; ~200km from Sachs Harbour). Data will also be collected during helicopter surveys of the south and west coast and the interior of Prince Patrick Island from 75°45'N to 77°40'N and from 119°W to 123°10'W, and Banks Island from 71°N to 74°45'N and 115°W to 123°W.