Reconstructing Landscape Evolution History Using Geological Data and Numerical Modelling

作为了解气候变化如何影响我们生活环境的努力的一部分，景观演变的研究领域正变得越来越重要。例如，在高山地区，了解冰川消退和永久冻土融化对侵蚀的影响，将为估计地貌灾害、活动断层地震活动和山地生态系统栖息地变化的风险提供科学依据。巨大的山脉是由板块构造和气候塑造而成的。这些外部强迫之间的强烈反馈使得利用观测资料解释它们各自对山地景观演变的贡献变得复杂。数值模拟为量化景观对变化条件的响应提供了一个有价值的工具，但不同侵蚀过程的相对重要性和侵蚀模型中的主要参数都需要更好地约束。我的研究项目将通过结合经验观察和数值方法，调查具有对比构造和气候条件的山脉景观历史。我将使用多种热年代学方法评估不同时间尺度上山脉的岩石挖掘和侵蚀历史。通过基岩冷却年龄推断构造变形模式，通过沉积物物源分析绘制侵蚀强度在山地和流域尺度上的空间分布图。估算的侵蚀模式将与不同侵蚀因子的分布进行比较，如冰川下降、河流切割和山体滑坡，以评估它们在改变山地景观方面的相对重要性。最后，其他经验数据集（如沉积物通量、盆地平均侵蚀率、气候历史）将被汇编并用于约束模拟自然景观历史的数值模型。模型将通过迭代减少模型预测和观测数据之间的不拟合来优化。在这个资助期内，我的优先领域是海岸山脉的南部，不列颠哥伦比亚省和中国东部的天山。海岸山脉是由反复的冰川作用雕刻而成的。在基岩和碎屑热年代学的基础上，我将研究冰期-间冰期过渡期间，特别是最后一次消冰期的侵蚀模式。相比之下，中国天山位于半干旱气候区，其北部山前有一系列深切的河流阶地。我将估计上游的侵蚀和泥沙运输和沉积过程，以了解构造隆升和气候变化如何控制下游环境中河流和冲积阶地的形成和保存。

As part of the effort to understand how climate change will impact our living environment, the research field of landscape evolution is becoming increasingly important. For example in high mountain ranges, knowing the impacts on erosion from retreating glaciers and thawing permafrost will provide a scientific basis for estimating risks of geomorphic hazards, seismicity on active faults, and habitat changes in mountain ecosystems. Large mountain ranges are created by plate tectonics and sculpted by climate. The strong feedbacks between these external forcings complicate the interpretation of their respective contribution to mountain landscape evolution from observational data. Numerical modelling provides a valuable tool for quantifying how landscapes respond to changing conditions, but both the relative importance of different erosion processes and the main parameters in the erosion models need to be better constrained. My research program will investigate the landscape histories of mountain ranges with contrasting tectonic and climatic conditions, by combining empirical observation and numerical methods. I will evaluate the rock exhumation and erosion histories of the mountain ranges over different time scales using multiple thermochronological methods. Bedrock cooling ages will be collected to infer the tectonic deformation pattern, whereas sediment provenance analysis will be applied to map the spatial distribution of the erosion intensity on mountain and catchment scales. The estimated erosion pattern will be compared to the distribution of rates of different erosion agents, such as glacial downcutting, fluvial incision, and landslides, in order to assess their relative significance in transforming the mountain landscape. Finally, other empirical datasets (e.g., sediment flux, basin-averaged erosion rate, climate history) will be compiled and used to constrain numerical models that simulate the history of a natural landscape. The models will be optimised by iteratively reducing the misfits between the model predictions and the observed data. For this funding period, my prioritised field areas are the southern part of the Coast Mountains, British Columbia and the eastern Chinese Tian Shan. The Coast Ranges were carved by repeated glaciations. Based on bedrock and detrital thermochronology, I will investigate the erosion patterns during the glacial-interglacial transitions, especially during the last deglaciation. In contrast, the Chinese Tian Shan sits in a semiarid climate zone, featuring a series of deeply incised river terraces on its north piedmont. I will estimate the upstream erosion and sediment transport and deposition processes, in order to understand how tectonic uplift and climate change control the formation and preservation of the fluvial and alluvial terraces in the downstream environment.