GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitrePalynological analysis of Danny's Lake, central Northwest Territories
AuteurSulphur, K C; Galloway, J M; Hills, L V; Crann, C; Macumber, A; Patterson, R T; Falck, H
Source40th Annual Yellowknife Geoscience Forum Abstracts of Talks and Posters ; par Watson, D M (éd.); Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2012, 2012 p. 70-71
Année2012
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130115
Réunion 40th annual Yellowknife Geoscience Forum; Yellowknife; CA; Novembre 13-15, 2012
Documentpublication en série
Lang.anglais
Mediapapier
Formatsdoc; pdf
ProvinceTerritoires du Nord-Ouest
SNRC76D/01
Lat/Long OENS-110.2500 -110.0000 64.5000 64.2500
Sujetsglace; épaisseurs des glaces; végétation; fluctuations climatiques; climat; climat arctique; paléontologie; géologie de l'environnement
Programmeadaptation et impacts sur l'environnement, environnement du nord, Géosciences de l'environnement
LiensOnline - En Ligne
Résumé(disponible en anglais seulement)
The Tibbitt to Contwoyto Winter Road (TCWR) is the critical link in the supply chain to northern diamond mines, including the Diavik Diamond Mine (Rio Tinto Group) and Ekati Diamond Mine (NHP Billiton Inc.). Use of the TCWR is limited to only a few months of the year because the road is built over frozen lakes; cold winter temperatures are required to maintain sufficient ice thickness. Northwest Canada has experienced some of the most rapid warming (on the order of 1.5 to 2° C per decade) in the Northern Hemisphere during the last few decades and climate models predict continued temperature increases for at least the next century. Recent climate fluctuations have resulted in a reduction of ice cover duration and thickness along the route of the TCWR, which has substantial economic impact for northern industries. Understanding cyclic climate phenomena in the Northwest Territories will enhance our ability to predict future climate and the impact on the TCWR. However, instrumental climate records extend only to the 1940's in the Northwest Territories. To place recent climate change in a geologic perspective, proxy records must be used. Palynology, the study of pollen and spores, is one of the best means for reconstructing past climate.

Danny's Lake (63º 28' 32'' N; 112º 32' 47'' W) is the first lake to the north of the 49th land portage along the TCWR and is approximately 17 km south of Lac de Gras and the Diavik Diamond Mine. It is located near the important ecotone boundary of the transition from boreal forest to tundra and is thus situated in a sensitive recording area where past climate change can be determined. A 111-cm sediment core was taken from Danny's Lake in March, 2010. These lake sediments contain well-preserved pollen and spores and microscopic charcoal. Pollen and spores will be used to reconstruct how vegetation communities in the central Northwest Territories have changed over the past ~3500 years. These changes in plant communities have ecological implications that can be related to climate variations. In this way, a palynological study can be used as a proxy of climate, and thus document past climate cycles. These past climate cycles can then be used to predict future climate cycles, and therefore aid in predicting the future viability. Microscopic charcoal will also be analyzed in sediment core samples from Danny's Lake to investigate fire regimes in the study region, how fire regimes have been affected by climate change, and how vegetation communities have responded to fire disturbance. Understanding disturbance regimes, and community response to fire disturbance, is important because occurrences of fires are affected by weather variations, and long-term trends in climate. Lightning strikes are major sources of tundra fires. The variations in weather and length of the storm season are affected by long-term climatic changes. This palynological study will help reconstruct the climate history of the area, and aid in predicting future climate cycles that will affect the TCWR, and thus the natural resource development in the north.
Résumé(Résumé en langage clair et simple, non publié)
L'analyse du pollen dans les sédiments prélevés dans le lac Danny, dans la partie centrale des T.N.-O. indique que cette région a connu des changements climatiques considérables au cours des 8 500 dernières années environ. Les feux de brousse étaient fréquents dans l'environnement arbustif de la toundra au début de l'Holocène, à l¿époque où le climat était chaud et sec. Le refroidissement néo-glaciaire a déplacé la limite forestière vers le nord et a réduit l'intensité et la fréquence des feux de forêt. Les échantillons de pollen enregistrent les événements climatiques qui ont sévi dans tout l'hémisphère, par exemple la Période chaude médiévale et le Petit âge glaciaire. Ces deux événements peuvent être utilisés aux fins de comparaison pour établir la réponse environnementale aux changements climatiques à venir.
GEOSCAN ID292738