The evolution of western Arctic landscape during the past 5 million years

过去500万年北极西部地貌的演变

• 批准号: 362148-2013
• 负责人: Gosse, John
• 金额: $ 1.09万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Northern Research Supplement
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=628533
• 关键词: evolution; western; Arctic; landscape; during

Besides glacial erosion, there is no other more dramatic change in Arctic landscape in the past 5 million years than the deposition and incision of the Beaufort Formation sedimentary wedge in the western Canadian Arctic Archipelago (CAA). Sediments were eroded from the east and deposited onto western islands and into the Canada Basin and Beaufort Sea. The result was a voluminous wedge of stream sediments that extended over 1200 km from the Yukon to Meighen Island. Sediment thicknesses reach more than 3 km offshore, and the channels that separate the islands were filled above the contemporaneous high sea level. Because this occurred during a relatively warm global climate when water no longer circulated through the CAA to cool the island, the sediments were interbedded with forest beds and supported a wide variety of flora and fauna, including hemlock and camels. The significant effort to collect and analyse these records of Arctic paleoenvironmental change has demonstrated, for instance, how sensitive the Arctic climate is (2°C of global warming translates to 15°C warming on Ellesmere Island, due to various sea ice and other feedbacks). But was global warming the only condition necessary to trigger such a wide-scale landscape response? Did tectonic processes, sea level change, and subsidence of the western margin play primary roles? The proposed research aims to significantly improve the chronology of the Beaufort Formation and similarly-aged sediments around the western CAA. This will help place the many isolated paleoenvironmental records into a chronological framework and link disparities in the paleoclimate records to temporal differences or spatial variation. Further, a precise chronology will provide a means to i) test hypotheses regarding the controls on deposition and incision of the clastic wedge, ii) relate the coastal sediments to high terraces inland and submerged Canada Basin shelf sediments, and iii) evaluate what feedbacks (sea ice, opening of paleoceanographic gateways) were necessary for such a significant landscape and environmental change. Besides a significant impact on our understanding of these events, the insights into sediment flux and rates of the processes will inform models of Arctic Ocean sedimentation used for evaluating hydrocarbon potential.

除了冰川侵蚀，在过去的500万年里，北极景观没有其他比加拿大北极群岛（CAA）西部博福特组沉积楔的沉积和切割更戏剧性的变化了。沉积物从东部被侵蚀，沉积在西部岛屿上，进入加拿大盆地和博福特海。其结果是形成了一个从育空地区到Meighen岛长达1200多公里的巨大楔形水系沉积物。沉积物厚度达到离岸3公里以上，分隔岛屿的水道被填充在同期高海平面以上。由于这发生在一个相对温暖的全球气候，当水不再通过CAA循环冷却岛屿时，沉积物与森林床互层，并支持各种各样的植物群和动物群，包括铁杉和骆驼。收集和分析这些北极古环境变化记录的重大努力已经证明了北极气候的敏感性（由于各种海冰和其他反馈，全球变暖2 °C转化为埃尔斯米尔岛15 °C的变暖）。但是，全球变暖是引发这种大规模景观反应的唯一必要条件吗？构造过程、海平面变化和西缘沉降是否起了主要作用？拟议的研究旨在显着改善博福特组和类似的年龄沉积物周围的西部CAA的年代。这将有助于将许多孤立的古环境记录纳入时间框架，并将古气候记录中的差异与时间差异或空间变化联系起来。此外，一个精确的年表将提供一种手段，i）测试假设的碎屑楔的沉积和切割的控制，ii）沿海沉积物与高阶地内陆和淹没加拿大盆地陆架沉积物，和iii）评估什么样的反馈（海冰，开放的古海洋学网关）是必要的，这样一个显着的景观和环境变化。除了对我们理解这些事件产生重大影响外，对沉积物通量和过程速率的了解将为用于评估碳氢化合物潜力的北冰洋沉积模型提供信息。