Abstract
Abstract. Information about past climate, tectonics, and landscape evolution is often obtained by dating geomorphic surfaces comprising deposited or aggraded material, e.g. fluvial fill terraces, alluvial fans, volcanic flows, or glacial till. Although surface ages can provide valuable information about these landforms, they can only constrain the period of active deposition of surface material, which may span a significant period of time in the case of alluvial landforms. In contrast, surface abandonment often occurs abruptly and coincides with important events like drainage reorganization, climate change, or landscape uplift. However, abandonment cannot be directly dated because it represents a cessation in the deposition of dateable material. In this study, we present a new approach to inferring when a surface was likely abandoned using exposure ages derived from in situ-produced cosmogenic nuclides. We use artificial data to measure the discrepancy between the youngest age randomly obtained from a surface and the true timing of surface abandonment. Our analyses simulate surface dating scenarios with variable durations of surface formation and variable numbers of exposure ages from sampled boulders. From our artificial data, we derive a set of probabilistic equations and a MATLAB tool that can be applied to a set of real sampled surface ages to estimate the probable period of time within which abandonment is likely to have occurred. Our new approach to constraining surface abandonment has applications for geomorphological studies that relate surface ages to tectonic deformation, past climate, or the rates of surface processes.
Highlights
Geomorphological studies that link the formation of landforms to past changes in climate or tectonic deformation depend on the accurate dating of surfaces comprising aggraded or deposited material
We derive a set of probabilistic equations and a MATLAB tool that can be applied to a set of real sampled surface ages to estimate the probable period of time within which abandonment is likely to have occurred
Our study uses artificial data to simulate depositional geomorphic surfaces that form over a non-negligible time span, and are subsequently dated with exposure ages on a set of randomly sampled boulders
Summary
Geomorphological studies that link the formation of landforms to past changes in climate or tectonic deformation depend on the accurate dating of surfaces comprising aggraded or deposited material. Surfaces commonly targeted for dating include alluvial fans, fluvial fill terraces, glacial till, pediments, and volcanic flows, among others. The ages of fluvial fill terraces and alluvial-fan surfaces have been used to (i) decipher how erosion and sedimentation have responded to past hydroclimate changes (Owen et al, 2014; Schildgen et al, 2016; Tofelde et al, 2017); (ii) derive timeintegrated slip rates for active faults From the set of exposure ages obtained, an average surface age can be calculated with an uncertainty that reflects both analytical uncer-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
