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Abstract Terrestrial cosmogenic nuclides (TCN) are widely employed to infer denudation rates in mountainous landscapes. The calculation of an inferred denudation rate (Dinf) from TCN concentrations is typically performed under the assumptions that denudation rates were steady during TCN accumulation and that soil chemical weathering negligibly impacted soil mineral abundances. In many landscapes, however, denudation rates were not steady and soil composition was significantly impacted by chemical weathering, which complicates interpretation of TCN concentrations. We present a landscape evolution model that computes transient changes in topography, soil thickness, soil mineralogy, and soil TCN concentrations. We used this model to investigate TCN responses in transient landscapes by imposing idealized perturbations in tectonically (rock uplift rate) and climatically sensitive parameters (soil production efficiency, hillslope transport efficiency, and mineral dissolution rate) on initially steady‐state landscapes. These experiments revealed key insights about TCN responses in transient landscapes. (a) Accounting for soil chemical erosion is necessary to accurately calculateDinf. (b) Responses ofDinfto tectonic perturbations differ from those to climatic perturbations, suggesting that spatial and temporal patterns inDinfare signatures of perturbation type and magnitude. (c) If soil chemical erosion is accounted for, basin‐averagedDinfinferred from TCN in stream sediment closely tracks actual basin‐averaged denudation rate, showing thatDinfis a reasonable proxy for actual denudation rate, even in many transient landscapes. (d) Response times ofDinfto perturbations increase with hillslope length, implying that response times should be sensitive to the climatic, biological, and lithologic processes that control hillslope length.
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This content will become publicly available on November 1, 2026
Climatic controls on soil production, transport and chemical erosion: Insights from modelling topography, soils and cosmogenic nuclides at Little Lake, Oregon
Abstract Predicting physical and chemical erosion rate responses to climate change are an ongoing challenge in geomorphology. A promising approach for investigating this is by measuring transient variations in physical and chemical erosion rates during climatically variable time periods, which can be accomplished by measuring cosmogenic nuclide concentrations and chemical depletion in sedimentary deposits. Interpreting such measurements warrants applying landscape evolution models that track variations in topography, cosmogenic nuclide concentrations and chemical depletion in soils. We applied a recently developed model that tracks these quantities at Little Lake, Oregon. Previous studies documented variations in cosmogenic nuclide concentrations and chemical depletion in paleo‐lake sediments from 50 ka BP to the present, a time interval that includes cooling before the Last Glacial Maximum and warming after it. We extended the model by adding climate‐sensitive parameterizations for mineral dissolution, soil transport by frost heave and soil production by frost cracking. We conducted simulations driven by a paleo‐temperature time series applicable to Little Lake. Simulations showed that a shift to frost heave, frost cracking and temperature‐controlled mineral weathering and alteration elevated10Be‐inferred denudation rates and lowered chemical depletion fraction (CDF) values comparable to those observed in cores from paleo‐Little Lake. In contrast, introducing a lake with no changes to process operation led to a decline in denudation rates. No single climate‐sensitive process could reproduce both high inferred denudation rates and low CDF, indicating that all of the climate‐sensitive processes modelled in our simulations are needed to explain observed values. Modelled denudation rates increased when the connection between frost cracking intensity and maximum soil production rate was strengthened. The integration of climate‐sensitive processes showed that a handoff from biotically driven processes to frost‐driven ones could induce large, detectable changes in both inferred denudation rate from10Be and CDF, signalling the potential for globally heterogeneous climate‐denudation rate linkages.
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- Award ID(s):
- 2045433
- PAR ID:
- 10683367
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Earth Surface Processes and Landforms
- Volume:
- 50
- Issue:
- 14
- ISSN:
- 0197-9337
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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