How fast is the denudation of the Taiwan mountain belt? Perspectives from in situ cosmogenic 10Be

• In Taiwan, we measured [10Be] in river quartz mineral to derived denudation rates.
• Pattern of basin-wide denudation rates reflects the mountain building processes.
• Our results fill a critical gap helping understanding the evolution of Taiwan.

Quantifying denudation rates in a wide range of climatic and tectonic settings at various time and space scales is a critical step in calibrating and validating landscape evolution models. Focusing on Taiwan, we quantified centennial rates of denudation at the scale of the whole orogen, using in situ 10Be concentrations measured in stream sediments collected at the outlets of major rivers. To assess denudation rates that are statistically significant, we applied both the mean square weighted deviation approach and the bootstrap technique. For the central segment of the belt, where the collision is considered to be near mature, the orogen-scale pattern of denudation shows a two-fold pattern: (1) higher denudation values on the order of 4–5 mm/yr characterize the eastern side of the belt (i.e., retro-wedge), with a slight increase towards the south and (2) lower denudation values on the order of 1–3 mm/yr on the western side of the belt (pro-wedge) with a minimum value centered on the main recess of the deformation front. To the north and to the south of the central segment, the denudation rates converge towards lower values on the order of 2–3 mm/yr. At the scale of the mountain belt, drainage basin metrics such as relief, hypsometric index and slope values seem to explain the observed variance in the data population, conversely to the first-order average precipitation pattern, suggesting a strong tectonic control on the regional pattern of denudation rates. Applied to the whole orogen, such field-based approach thus provides important input data to validate and calibrate the parameters to be supplied to landscape evolution models.