Denudation and weathering rates of carbonate landscapes from new cosmogenic methods

Karst landscapes provide vital services to humans, but the rates and controls of carbonate rock weathering and erosion, in sum termed denudation (D), are not well constrained. To address this gap, we adapted a framework using the cosmogenic meteoric¹⁰Be/⁹Be ratio. Radioactive ¹⁰Beryllium (Be) traces atmospheric input, while stable ⁹Be indicates weathering. This method can be performed on water, soil, sediment, or travertine, does not rely on specific minerals like quartz or calcite, and D can be partitioned into weathering and erosion rates. Extensive testing showed that the method is suitable for both pure limestone and mixed carbonate-siliciclastic settings.

We employed the ¹⁰Be/⁹Be method to the temperate limestone-rich French Jura Mountains, obtaining rates of catchment-wide D (from sediment) and point source D (from soil). Average D range from 300-500 t/km²/yr, with denudation primarily driven by weathering (W/D>0.92), and a non-negligible contribution to weathering from deep (below soil). These rates are consistent within a factor of two when compared to decadal-scale D derived from combined suspended and dissolved fluxes, underscoring the substantial potential of this method for Earth surface research in karst landscapes.

On a global scale, our data provide the first cosmogenic nuclide‐based denudation rates for the mean annual precipitation (MAP) range of 1,200–1,700 mm/yr under dense vegetation cover. At similar MAPs, our rates exceed previous rates derived from e.g. in situ ³⁶Cl measured in calcite from less vegetated sites. Altogether, global D patterns suggest a control of precipitation on D and/or W that may be modulated by vegetation cover.