¹⁰Be-derived denudation rates from the Burdekin catchment: The largest contributor of sediment to the Great Barrier Reef

Terrestrial cosmogenic nuclides (TCNs) such as Beryllium-10 (¹⁰Be) are now routinely used to reconstruct erosional rates over tens of thousands of years at increasingly large basin scales (>100,000km²). In Australia, however, the approach and its assumptions have not been systematically tested within a single, large drainage basin. This study measures ¹⁰Be concentrations in river sediments from the Burdekin catchment, one of Australia's largest coastal catchments, to determine long-term (>10,000years), time-integrated rates of sediment generation and denudation. A nested-sampling design was used to test for effects of increasing catchment scale on nuclide concentrations with upstream catchment areas ranging from 4 to 130,000km². Beryllium-10 concentrations in sediment samples collected from the upstream headwater tributaries and mid-stream locations range from 1.8 to 2.89×10⁵atomsg^-1 and data confirm that nuclide concentrations are well and rapidly mixed downstream. Sediment from the same tributaries consistently yielded ¹⁰Be concentrations in the range of their upstream samples. Overall, no decrease in ¹⁰Be concentrations can be observed at the range of catchment scales measured here. The mean denudation rate for all river sediment samples throughout the Fanning subcatchment (1100km²) is 18.47mMa^-1, which compares with the estimate at the end of the Burdekin catchment (130,000km²) of 16.22mMa^-1. Nuclide concentrations in the lower gradient western and southern catchments show a higher degree of variability, and several complications emerged as a result of the contrasting geomorphic processes and settings. This study confirms the ability of TCNs to determine long-term denudation rates in Australia and highlights some important considerations in the model assumptions that may affect the accuracy of limited sampling in large, low-gradient catchments with long storage times.