Large-scale landscape responses to Cenozoic climatic and lithospheric processes

宇宙射线粒子与岩石中的原子相互作用时产生了地球宇宙成因核素(TCN)。它们的浓度被用来确定地球表面或附近自然过程的时间、速度和风格。拟议的研究计划旨在(I)测试一种原创和创新的方法，该方法使用地下数百米处的宇宙源µ子产生的同位素来确定数百万年来地形是如何演变的，我们称之为µ子古地形测量法，以及(Ii)扩大我们对加拿大发生的最大的景观演变之一的了解，以及它对北极未来变化的影响。(I)Muon古地形测量是可以实现的，因为我们对宇宙成因的Muon与原子相互作用的理解最近取得了进展，化学和分析方法也有了最近的改进。为了测试这种方法，我们从众多的(备份)地点中选择了两个地点，在那里，隧道提供了通往数十个地下样本的通道，这些样本需要解决一个有趣的问题。在瑞士，一个多世纪的研究旨在确定欧洲阿尔卑斯山的缓解过程。虽然其他技术可以提供一些洞察，但Muon古地形测量将确定地形是否主要是由过去2 Myr的冰川侵蚀造成的，或者是否大部分地形是由于早期的构造或气候因素而从溪流切割中继承下来的。在第二个地点，犹他州的科罗拉多河正在创造地形，一个巨大的沉坑坍塌留下了一个200米长的悬崖。悬崖形成事件的~1.7Myr年龄是独立已知的，该遗址提供了一个机会来探索峡谷地和荒地(如阿尔伯塔省南部)的陡峭如何以及如何快速地被侵蚀。(Ii)根据我们先前NSERC的研究结果，我们假设加拿大北极群岛在2.7百万年前并不存在，该地区被厚厚的一层主要是上新世(5.3至2.7百万年)的河流砾石覆盖，这些砾石后来被侵蚀。最近西北航道的开放是由于侵蚀，而不是构造作用，这可能会对加拿大的说法产生影响，即它们是在其他方面相连的陆地上的内水。我们试图：(A)提高我们对上新世水系沉积物来源附近的知识(Ellesmel is.的野外工作)；(B)利用在加拿大中部北极基岩中测量的TCN比率来确定倾斜的、前冰川时代的基岩表面是否显示出上新世的“埋藏”信号；以及(C)表明Bylot上的小块河流砾石是TCN埋葬年代和生物地层学曾经覆盖的广泛上新世沉积物的残留物。这些目标以及实验室和方法学发展的数量将涉及加拿大和国际合作者，并培训2名博士、2名硕士、1名PDF本科生，他们将掌握国际和北极研究、同位素化学、景观对气候变化的敏感性以及科学传播方面的知识。

Terrestrial cosmogenic nuclides (TCN) are produced when cosmic ray particles interact with atoms in rock. Their concentrations are used to establish the timing, rates, and styles of natural processes on or near Earth's surface. The proposed research program aims to (i) test an original and innovative method that uses isotopes produced from cosmogenic muons hundreds of metres underground to establish how topography evolved over millions of years, we call it muon paleotopometry, and (ii) expand our knowledge of one of the largest landscape evolutions that have occurred in Canada, and its implications for future change in the Arctic. (i) Muon paleotopometry is achievable because of recent developments in our understanding of how cosmogenic muons interact with atoms and recent improvements in chemistry and analytical methods. To test the approach, we have selected two locations among numerous (backup) sites, where tunnels provide access to dozens of underground samples needed to solve an interesting question. In Switzerland, over a century of research has aimed at determining the processes responsible for the relief of the European Alps. While other techniques can provide some insight, the muon paleotopometry will determine if the topography is mostly caused by glacial erosion in the past 2 Myr, or if much of the relief was inherited from stream incision in response to earlier tectonic or climate factors. At the second location, a large sink-hole collapse left a 200-m escarpment as relief was being created by the Colorado River in Utah. The ~1.7 Myr age of the scarp-forming event is known independently and the site provides an opportunity to explore how and how fast scarps erode in canyonlands and badlands such as in southern Alberta. (ii) From results of our previous NSERC research, we hypothesize that the Canadian Arctic Archipelago did not exist as recently as 2.7 Myr ago, and that the region was covered by a thick layer of mostly Pliocene (5.3 to 2.7 Myr) stream gravels which have since been eroded. A recent opening of the Northwest Passages by erosion, not tectonics, may have implications for Canada's claim that they are internal waters within an otherwise contiguous landmass. We seek to (a) improve our knowledge of the Pliocene stream sediments near their sources (field work on Ellesmere Is.); (b) use ratios of TCN measured in bedrock in central Arctic Canada to determine if tilted, pre-glacial bedrock surfaces exhibit a Pliocene `burial' signal; and (c) show that pockets of stream gravels on Bylot Is are remnants of the once extensive Pliocene sediment cover by TCN burial dating and biostratigraphy. These goals and number of lab and methodological developments will involve Canadian and international collaborators, and train 2 PhD, 2MSc, 1PDF, undergraduates who will become knowledgeable in international and Arctic research, isotope chemistry, the sensitivity of landscapes to climate change, and science communication.