Large-scale landscape responses to Cenozoic climatic and lithospheric processes

对新生代气候和岩石圈过程的大尺度景观响应

• 批准号: RGPIN-2019-06785
• 负责人: Gosse, John
• 金额: $ 4.44万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=691047
• 关键词: Large; scale; landscape; responses; Cenozoic

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. *****

地球上的宇宙成因核素（TCN）是宇宙射线粒子与岩石中的原子相互作用产生的。它们的浓度被用来确定地球表面或附近自然过程的时间、速率和风格。拟议的研究计划旨在（i）测试一种原创和创新的方法，该方法使用数百米地下宇宙成因μ子产生的同位素来确定数百万年来地形如何演变，我们称之为μ子古地形学，以及（ii）扩大我们对加拿大发生的最大景观演变之一的了解，及其对北极未来变化的影响。***（i）μ子古拓扑学是可以实现的，因为我们对宇宙成因μ子如何与原子相互作用的理解最近取得了进展，而且化学和分析方法最近有所改进。为了测试这种方法，我们在众多（备份）站点中选择了两个位置，在那里，隧道提供了解决一个有趣问题所需的数十个地下样本。在瑞士，经过世纪的研究，人们一直致力于确定欧洲阿尔卑斯山起伏的过程。虽然其他技术可以提供一些见解，μ子古地形测量法将确定地形是否主要是由过去200万年的冰川侵蚀造成的，或者大部分地形是否是由于早期构造或气候因素而从河流切割中继承的。在第二个地点，一个大的天坑坍塌留下了一个200米的悬崖，因为科罗拉多河在犹他州正在创造救济。陡坎形成事件的年龄约为170万年，该遗址为探索陡坎在峡谷地和荒地（如阿尔伯塔南部）的侵蚀方式和速度提供了机会。* (ii)根据我们以前的NSERC研究结果，我们假设加拿大北极群岛在270万年前并不存在，该地区被一层厚厚的上新世（530万至270万年）河流砾石所覆盖，这些砾石已经被侵蚀。最近西北通道的开放是由于侵蚀，而不是构造，这可能对加拿大的主张产生影响，加拿大声称西北通道是一个相邻大陆块内的内部沃茨。我们寻求（a）提高我们对上新世河流沉积物来源附近的知识（埃尔斯米尔群岛的实地工作）; (b)使用在加拿大北极地区中部基岩中测量的TCN比率，以确定倾斜的冰前基岩表面是否显示出上新世埋藏的信号;以及（c）通过TCN埋藏年代测定和生物地层学，表明Bylot Is上的溪流砾石袋是曾经广泛的上新世沉积物覆盖的残余物。这些目标和实验室和方法发展的数量将涉及加拿大和国际合作者，并培养2名博士，2名硕士，1名PDF，本科生，他们将成为国际和北极研究，同位素化学，景观对气候变化的敏感性和科学传播方面的知识。*****