The Last (Koy-Yukon) Interglaciation in the Northern Yukon: Evidence from Unit 4 at Ch’ijee’s Bluff, Bluefish Basin

• Published in: Géographie physique et Quaternaire
• Main Authors: Matthews, John V., Schweger, Charles E., Janssens, Jan A.
• Format: Text
• Language: English
• Published: Les Presses de l'Université de Montréal 1990
• Subjects: Yukon; Old Crow; Porcupine River
• Online Access: http://id.erudit.org/iderudit/032835ar; https://doi.org/10.7202/032835ar

The effects of predicted anthropogenic warming can be assessed in part by documenting responses to past warming events. One of the most pronounced warmings was the last interglaciation - stage 5 of the marine isotope record. A large multinational and multidisciplinary project (CELIA) was launched recently in order to gain detailed knowledge of the climate during stage 5. Several key exposures were identified by CELIA; one of them is Ch'ijee's Bluff on the Porcupine River, northern Yukon. Pollen, plant and insect macrofossils and stratigraphie evidence from Ch'ijee's Bluff show that the part of Ch'ijee's Unit 4 that is above and younger than Old Crow tephra (OCt) was deposited during an interval of climate warmer than present. When OCt was dated at 85 ka BP, the subsequent warming interval was presumed to be correlative with the early part of marine isotope stage 3. New dates on OCt show it to be 140-150 ka BP, and this means that the warm interval discussed here is more likely of stage 5 than stage 3 age. We apply the informal epithet, "Koy-Yukon interglaciation", to it and compare the Ch'ijee's Bluff Unit 4 sequence with other east Beringian sites that contain both Old Crow tephra and putative interglacial deposits. Les conséquences du réchauffement anthropique attendu pourraient en partie être évaluées à partir de nos connaissances sur les réchauffements climatiques antérieurs. Le réchauffement climatique le plus important s'est produit au cours du dernier interglaciaire (stade isotopique 5). Dans le but d'acquérir une meilleure connaissance du climat durant le stade 5, on a créé un important projet multidisciplinaire et multinational (CELIA). On a identifié plusieurs coupes clés dont celle de Ch'ijee's Bluff, de la Porcupine River, dans le nord du Yukon. Les indices fournis par le pollen, les végétaux, les macrofossiles d'insectes et la stratigraphie de Ch'ijee's Bluff démontrent que la partie de l'unité n 4 plus jeune que le tephra de Old Crow et située au-dessus a été déposée durant un intervalle plus ...