224-4 Pysochron: An open-source Python script for modeling cosmogenic 26Al/10Be isochron burial ages

Session: From the Cosmos and Back: Quantifying Processes and Rates of Landscape Change (Posters)

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Abstract:

Cosmogenic ²⁶Al/¹⁰Be burial dating is useful for constraining the depositional ages of quartz-bearing sediments over the past ~5 million years, but the method can be complicated by a number of factors that can influence the apparent age of a deposit. Incorporation of previously buried (i.e., reworked) materials can produce artificially old ages, given that ²⁶Al and ¹⁰Be record cumulative burial histories. Conversely, production of ²⁶Al and ¹⁰Be after burial by deeply penetrating cosmic radiation can work against burial-induced decay and cause deposits to appear younger than they actually are. These issues can be mitigated with ²⁶Al/¹⁰Be isochron burial dating, which uses ²⁶Al and ¹⁰Be measured from a suite of clasts in a deposit to model their shared burial age, identify potentially reworked clasts, and quantify postburial production in order to produce confident burial ages.

Pysochron (https://code.usgs.gov/recon/pysochron) provides an open-source, user-friendly tool for performing Monte Carlo ²⁶Al/¹⁰Be isochron burial dating calculations with a single Python script. Running the script opens a graphical user interface that allows users to modify production and decay constants, select different preburial erosion or exposure scenarios, tailor uncertainty calculations, and fine-tune isochron diagram outputs. Automated analyses of fitted isochrons provide quantitative and qualitative insights into model results, including mean square weighted deviation (MSWD) values, minimum burial ages of individual samples, outlier identification, and automated commentary on the robustness of isochron fits. This approach has been validated with 40 published ²⁶Al/¹⁰Be isochrons from around the world, with ages ranging from 4.9-0.2 Ma, and has been shown to perform reliably in all instances. Researchers using ²⁶Al/¹⁰Be isochron burial dating are invited to explore Pysochron’s capabilities and provide feedback to be incorporated into future versions of the software.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9240

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