Soil production and transport on postorogenic desert hillslopes quantified with 10Be and 26Al

26Al/10Be ratios reveal the source of river sediments in the Kimberley, NW Australia

“…Australia contains some of the oldest landforms on Earth (Twidale, 1998) and CRN based estimates of bedrock erosion as low as 1 m.Myr -1 obtained across the continent have demonstrably supported this conclusion (Bierman and Caffee, 2002;Belton et al, 2004;Ward et al, 2005;Heimsath et al, 2010;Struck et al, 2018b). Erosion rates recorded are among the lowest on Earth (e.g., Portenga and Bierman, 2011;Codilean et al, 2018), with lower rates only recorded in Antarctica.…”

“…First, the depressed 26 Al/ 10 Be signal is present in all the sampled basins with no clear relation between deviation from the 26 Al/ 10 Be steady-state erosion curve and increasing basin area, as might be expected given that the larger the basin area, the larger the potential for sediment trapping and burial occurring. Second, in the three rivers that were sampled in multiple locations along the trunk channel (i.e., Drysdale, Pentecost and King Edwards; Figure 1), obtained 26 Al/ 10 Be ratios do not decrease significantly downstream, as would be expected when sediments are buried along their route to the basin outlet (e.g., Struck et al, 2018b). Second, in the three rivers that were sampled in multiple locations along the trunk channel (i.e., Drysdale, Pentecost and King Edwards; Figure 1), obtained 26 Al/ 10 Be ratios do not decrease significantly downstream, as would be expected when sediments are buried along their route to the basin outlet (e.g., Struck et al, 2018b).…”

“…Erosion rates recorded are among the lowest on Earth (e.g., Portenga and Bierman, 2011;Codilean et al, 2018), with lower rates only recorded in Antarctica. Previous studies employing CRNs on Australian landscapes have focused on mechanisms of soil production (Heimsath et al, 2001;Heimsath et al, 2009), desert morphology and the onset of aridity (Fujioka et al, 2005;Fujioka et al, 2009), quantifying hillslope processes and sediment transport (Struck et al, 2018a(Struck et al, , 2018b, and studying the age of archaeological sites (Pillans and Fifield, 2013). Studies quantifying denudation rates on the basin scale have been few, with notable recent examples including work done in the Flinders Ranges of South Australia (e.g., Quigley et al, 2007;Bestland et al, 2016) and along the basins draining the eastern board of the Great Dividing Range (Nichols et al, 2014;Croke et al, 2015;Godard et al, 2019).…”

Quantifying erosional equilibrium across a slowly eroding, soil mantled landscape

“…burrowing animals, termites, and bioturbation due to tree root penetration (Heimsath et al, 2010). The relatively high proportion of bare ground favors greater removal of fine sediments by overland flow, consistent with the accumulation of coarse stone lags at the surface (Struck et al, 2018).…”

Fluvial dynamics and 14C‐10Be disequilibrium on the Bolivian Altiplano

“…For instance, hillslope inputs containing disequilibrium 26 Al/ 10 Be have been shown to profoundly affect the fluvial isotopic inventory in central Australian rivers (Struck et al, 2018a(Struck et al, , 2018b. Input of hillslope-derived materials with an inherited offset in its 14 C-10 Be inventory is certainly plausible.…”