• 标题：Tectonic controls on rates and spatial patterns of glacial erosion through geothermal heat flux
• 关键词：landscape evolution,glacial erosion,numerical modeling,geothermal heat
• 作者：Jingtao Lai, Alison M. Anders

 Clacial erosion has shaped many mountain belts during the cold periods of the Late Cenozoic. The rate of glacial erosion is sensitive to the subglacial environment, including both the subglacial hydrology and the basal thermal regime. Geothermal heat from underlying bedrock is a major contributor to glacier energy budgets, controlling ice dynamics at the ice-bed interface by changing the basal temperature and the supply of meltwater. Despite the known inflfluence of geothermal heat on the subglacial environment, its impact on glacial erosion has received little study. The geothermal heat flflux in glaciated mountain ranges varies widely as a function of the tectonic setting. Therefore, if glacial erosion is sensitive to geothermal heat flflux, the evolution of glaciated landscapes may depend upon tectonically-controlled geothermal gradients. We explore the impact of geothermal heat flflux on the rates and spatial patterns of glacial erosion in mountain ranges using numerical models. We couple a sliding-dependent glacial erosion model with the Parallel Ice Sheet Model (PISM) to simulate the evolution of a synthetic glacial landscape. We fifind a robust tendency for increasing glacial erosion with increasing geothermal heat flflux. The spatial pattern of erosion also varies with the magnitude of geothermal heat flflux. At low geothermal heat flflux, glacial erosion is consistently focused in major valleys. As geothermal heat flflux increases, the area of signifificant glacial erosion expands into higher elevations and the rate of erosion increases. The location of maximum erosion migrates up-valley as geothermal heat flflux increases, suggesting that glacial erosion tends to produce distinct landscapes as a function of geothermal heat flflux. Our fifinding suggests that active mountain belts with high geothermal heat flflux will express the glacial buzzsaw effect, in which high elevation topography is preferentially removed by glacial erosion. Glaciers at passive margins with low geothermal heat flflux, in contrast, will tend to incise deep valleys at relatively low elevations. Previous work on the interaction between tectonics and landscape evolution has focused on relief generation and fracturing of rocks. Our results introduce a novel potential linkage between tectonics and erosion based on the sensitivity of glacial erosion to geothermal heat.

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