A Combined Cosmogenic Nuclides Approach for Determining the Temperature‐Dependence of Erosion

Abstract

Physical weathering in cold, steep bedrock hillslopes occurs at rates that are thought to depend on temperature, but our ability to quantify the temperature‐dependence of erosion remains limited when integrating over geomorphic timescales. Here, we present results from a 1D numerical model of in‐situ cosmogenic 10Be, 14C, and 3He concentrations that evolve as a function of erosion rate, erosion style, and ground surface temperature. We used the model to explore the suitability of these nuclides for quantifying erosion rates in areas undergoing non‐steady state erosion, as well as the relationship between bedrock temperature, erosion rate, and erosional stochasticity. Our results suggest that even in stochastically eroding settings, 10Be‐derived erosion rates of amalgamated samples can be used to estimate long‐term erosion rates, but infrequent large events can lead to bias. The ratio of 14C to 10Be can be used to evaluate erosional stochasticity, and to determine the offset between an apparent 10Be‐derived erosion rate and the long‐term rate. Finally, the concentration of 3He relative to that of 10Be, and the paleothermometric interpretations derived from it, are unaffected by erosional stochasticity. These findings, discussed in the context of bedrock hillslopes in mountainous regions, indicate that the 10Be‐14C‐3He system in quartz offers a method to evaluate the temperature‐sensitivity of bedrock erosion rates in cold, high‐alpine environments.

Non‐Steady‐State 14C‐10Be and Transient Hillslope Dynamics in Steep High Mountain Catchments

“…Previously, paired 14 C-10 Be studies were hampered by the difficulty of measuring in situ 14 C (e.g., Lifton et al, 2001;Pigati et al, 2010), but recent advances in 14 C extraction techniques make utilizing this nuclide more feasible (e.g., Lifton et al, 2015;Lupker et al, 2019). As a consequence, several new studies using paired 14 C-10 Be have identified complex erosional histories (e.g., Hippe et al, 2012Hippe et al, , 2019Hippe et al, , 2021Kober et al, 2019) and explored emerging applications (Dennis & Scherler, 2022;Schimmelpfennig et al, 2021). However, efforts to understand non-steady-state sediment transport dynamics from paired 14 C-10 Be are still in their infancy (e.g., Hippe, 2017;Hippe et al, 2019Hippe et al, , 2021, and to date few studies have utilized this pairing in high-relief, mountainous terrain (Dennis & Scherler, 2022;Kober et al, 2012Kober et al, , 2019.…”

“…As a consequence, several new studies using paired 14 C-10 Be have identified complex erosional histories (e.g., Hippe et al, 2012Hippe et al, , 2019Hippe et al, , 2021Kober et al, 2019) and explored emerging applications (Dennis & Scherler, 2022;Schimmelpfennig et al, 2021). However, efforts to understand non-steady-state sediment transport dynamics from paired 14 C-10 Be are still in their infancy (e.g., Hippe, 2017;Hippe et al, 2019Hippe et al, , 2021, and to date few studies have utilized this pairing in high-relief, mountainous terrain (Dennis & Scherler, 2022;Kober et al, 2012Kober et al, , 2019.…”