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

除了冰川侵蚀，在过去的500万年里，北极地貌没有比加拿大西部北极群岛(CAA)波弗特组沉积楔形沉积和切割更戏剧性的变化。沉积物从东部被侵蚀，沉积到西部岛屿，进入加拿大盆地和波弗特海。其结果是形成了一个巨大的水系沉积物楔形，从育空延伸到湄洲岛，绵延1200多公里。近海的沉积物厚度达到了3公里以上，分隔岛屿的航道被填满了当时的高海平面。由于这发生在相对温暖的全球气候期间，当水不再通过CAA循环冷却该岛时，沉积物与森林床互层，并支持包括铁杉和骆驼在内的各种动植物。收集和分析这些北极古环境变化记录的重大努力表明，例如，北极气候是多么敏感(由于各种海冰和其他反馈，全球变暖2摄氏度转化为埃尔斯米尔岛15摄氏度的变暖)。但是，全球变暖是引发如此大规模的景观反应的唯一必要条件吗？构造过程、海平面变化和西部边缘的下沉是否起了主要作用？这项拟议的研究旨在显著改善波弗特组和西部CAA周围类似年代的沉积物的年代学。这将有助于将许多孤立的古环境记录纳入一个时间框架，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，精确的年代学将提供一种手段来测试关于碎屑楔沉积和切割的控制假说，ii)将沿海沉积物与内陆高阶地和加拿大盆地水下陆架沉积物联系起来，以及iii)评估对于如此重大的地貌和环境变化需要什么反馈(海冰，古海洋学门户的打开)。除了对我们对这些事件的理解产生重大影响外，对沉积物通量和过程速率的洞察还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。

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.****