Late cenozoic of the Canadian Arctic archipelago and the southern central Andes

我感兴趣的是地球的景观如何在不同的时间尺度上演变。 两种用于确定数千年至数亿年时间尺度上表面过程的速率和时间的年代学方法正在彻底改变地球科学家分析景观演变的方式。 当宇宙射线与地球表面上层几米处暴露的矿物相互作用时产生的陆地宇宙成因核素被用来直接确定地貌变化事件发生的时间，如过去冰川的时间、基岩表面或冲积扇等应变标志的地震偏移或火山爆发。 下切的峡谷壁和基岩斯特拉特阶地的暴露年龄可以提供有关选定河段河流的下切率变化的信息。 此外，TCN还可用于估算从个别山峰到整个溪流集水区数千年至数百万年时间尺度的短期和长期平均侵蚀率。 第二种方法，（U-Th-Sm）/He低温热年代学，用于估计地球表面岩石的冷却历史，因为它是从2至4公里的深度挖掘出来的（矿物可能会以不同的速度冷却，因为他们上升）。 该技术适用于数万至数亿年的时间尺度，也可用作火山灰年代学工具（用于测定史前火山灰中的矿物）。 耦合这两种方法的优点是，一个更完整的了解景观演变可能会达到，以解决问题，如：（1）什么是历史的地震断层在安第斯山脉？(2)加拿大地盾（潜在的核废料储存库）的侵蚀历史是什么？(3)整个北极中部广阔的自然地理表面的演化历史是什么？ 对这个问题的回答有助于降低北极石油和矿产勘探的风险。这些技术的设施已经在达尔豪西建立，我的研究计划将有助于培养同位素和环境地球化学方面的本科生和研究生、技术人员和访问研究人员。

I am interested in how Earth's landscapes have evolved over different timescales. Two chronological methods for determining rates and timing of surface processes at timescales between thousands and hundreds of millions of years are revolutionizing the way Earth Scientists analyse landscape evolution. Terrestrial cosmogenic nuclides (TCNs) produced when cosmic rays interact with exposed minerals in the upper few metres of Earth's surface are used to directly date when landscape change events have occurred, such as the timing of past glaciations, seismic offset of strain markers such as bedrock surfaces or alluvial fans, or the eruption of volcanoes. Exposure ages of incised canyon walls and bedrock strath terraces can provide information about the variability in incision rates of selected reaches of streams. Additionally, TCNs can be used to estimate short- and long-term averaged erosion rates of spatial scales from individual mountain peaks to entire stream catchments over timescales of thousands to millions of years. The second method, (U-Th-Sm)/He low temperature thermochronology, is used to estimate the cooling history of a rock on Earth's surface since it was exhumed from depths of two to four kilometres (minerals may cool at variable rates as they ascend). The technique is applicable over timescales of tens of thousands to hundreds of millions of years, and can also be used as a tephrochronology tool (to date minerals in pre-historic volcanic ash). The advantage in coupling both methods is that a more complete understanding of landscape evolution may be attained, in order to address questions such as: (1) What is the history of earthquake faulting in the Andes? (2) What is the erosion history of the Canadian shield (potential nuclear waste repository)? (3) What is the evolutionary history of the expansive physiographic surfaces throughout the Central Arctic? Answers to this question help reduce risk to petroleum and mineral exploration in the Arctic. The facilities for these techniques have been established at Dalhousie and my research program will help train undergraduate and graduate students, technical staff, and visiting researchers in aspects of isotope and environmental geochemistry.