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Changements climatiques et écologiques dans le nord de l’Alaska au cours de la glaciation du Wisconsinien : le Yedoma de la rivière Itkillik
| Content Provider | Semantic Scholar |
|---|---|
| Author | Elmrabti, Lyna Lapointe |
| Copyright Year | 2016 |
| Abstract | The cold-arid climate associated with the Wisconsinan glaciation in Beringia has led to the formation of a relict form of syngenetic permafrost, termed yedoma. These deposits contain various environmental proxies that can be used to reconstruct the climatic and ecological dynamics across Beringia prior to the Last Glacial Maximum (LGM). To date, only a few studies have attempted to reconstruct LGM climate north of the Brooks Range and the regional ecological heterogeneity of eastern Beringia is still poorly understood. The present thesis focuses on paleoenvironmental reconstructions of northern Alaska spanning about 39 ka, based on sediments from the Itkillik river Yedoma. The objectives are (1) to reconstruct the regional vegetation history from pollen analysis; (2) to reconstruct the July temperatures, seasonal temperature contrast and July sunshine based on the modern analogue technique applied to pollen and (3) to link the biogeochemical and glaciological records to the reconstructed climate. The study shows that around 35 ka BP (Middle Wisconsinan), climate conditions were similar than modern and favored the accumulation of peat and organic carbon. From 29.7 ka BP, July temperature decreased as continentality increased. Ice content was low and the vegetation was dominated by Poaceae, Artemisia and other non-graminoid indicators of xeric environmental conditions. Isotopic anomalies of O, H and deuterium excess indicate a glacial advance (Late Wisconsinan). Improving climate and ecological conditions is recorded after 17.9 ka BP (Late Glacial). Overall, the results are more similar to reconstructions of other sites located in northern and interior Alaska than those from interior Yukon or western Beringia. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://papyrus.bib.umontreal.ca/xmlui/bitstream/handle/1866/15930/Lapointe_Elmrabti_Lyna_2015_memoire.pdf?isAllowed=y&sequence=4 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
