Reconstructing Landscape Evolution History Using Geological Data and Numerical Modelling

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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.