Denudation and weathering rates of carbonate landscapes from meteoric 10Be/9Be ratios

Quantifying the rates at which carbonate rocks are denuded, the balance between chemical weathering and physical erosion, and their responsiveness to climate, vegetation, and tectonic activity is crucial for revealing feedback mechanisms in the carbon cycle and the dynamics of karst landscapes that provide vital services to humans. However, no existing method effectively partitions denudation into erosion and weathering fluxes. To estimate total denudation rates in carbonate terrains across spatial scales from soil to entire watersheds, we adapted a previously established framework that utilizes cosmogenic meteoric ¹⁰Be as an atmospheric flux tracer together with stable ⁹Be released during rock weathering. We employed the new method to the limestone-rich French Jura Mountains. By analyzing water, soil, sediment, travertine, and bedrock for ¹⁰Be/⁹Be ratios, as well as major and trace elements, stable carbon isotopes, and radiogenic strontium, we were able to quantify the contributions of beryllium from both primary and secondary carbonate phases and its release during the weathering of carbonate bedrock versus silicate impurities. We determined the partitioning of beryllium between solids and solutions and calculated rates of catchment-wide denudation (from sediment) and point source denudation (from soil), along with weathering and erosion rates. Our findings suggest that the average denudation rates range from 300 to 500 t/km²/yr, with denudation primarily driven by weathering intensity (W/D) ratios exceeding 0.92. These rates are consistent within a factor of two when compared to decadal-scale denudation rates derived from combined suspended and dissolved fluxes, underscoring the substantial potential of this method for Earth surface research in karst landscapes.