Preprints
https://doi.org/10.5194/egusphere-2024-702
https://doi.org/10.5194/egusphere-2024-702
13 Mar 2024
 | 13 Mar 2024
Status: this preprint is open for discussion.

Production rate calibration for cosmogenic 10Be in pyroxene by applying a rapid fusion method to 10Be-saturated samples from the Transantarctic Mountains, Antarctica

Marie Bergelin, Greg Balco, Lee B. Corbett, and Paul R. Bierman

Abstract. Measurements of multiple cosmogenic nuclides in a single sample are valuable for various applications of cosmogenic nuclide exposure dating and allow for correcting exposure ages for surface weathering and erosion and establishing exposure-burial history. Here we provide advances in the measurement of cosmogenic 10Be in pyroxene and constraints on the production rate which provide new opportunities for measurements of multi-nuclide systems, such as 10Be/3He, in pyroxene-bearing samples. We extracted and measured cosmogenic 10Be in pyroxene from two sets of Ferrar Dolerite samples collected from the Transantarctic Mountains in Antarctica. One set of samples has 10Be concentrations close to saturation which allows for the production rate calibration of 10Be in pyroxene by assuming production-erosion equilibrium. The other set of samples, which has a more recent exposure history, is used to determine if a rapid fusion method can be successfully applied to samples with Holocene to Last-Glacial-Maximum exposure ages. From measured 10Be concentrations in the near-saturation sample set we find the production rate of 10Be in pyroxene to be 3.74 +/- 0.10 atoms g-1 yr-1 and is consistent with 10Be/3He paired nuclide ratios from samples assumed to have simple exposure. Given the high 10Be concentration measured in this sample set, a sample mass of ~0.5 g of pyroxene is sufficient for the extraction of cosmogenic 10Be from pyroxene using a rapid fusion method. However, for the set of samples having low 10Be concentrations, measured concentrations were higher than expected. We attribute spuriously high 10Be concentration to potential failure in removing all meteoric 10Be and/or a highly variable and poorly quantified measurement background.

Marie Bergelin, Greg Balco, Lee B. Corbett, and Paul R. Bierman

Status: open (until 27 Apr 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-702', Anonymous Referee #1, 30 Mar 2024 reply
  • RC2: 'Comment on egusphere-2024-702', Samuel Niedermann, 09 Apr 2024 reply
Marie Bergelin, Greg Balco, Lee B. Corbett, and Paul R. Bierman
Marie Bergelin, Greg Balco, Lee B. Corbett, and Paul R. Bierman

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Short summary
Cosmogenic nuclides, such as 10Be, are rare isotopes produced in rocks when exposed at Earth’s surface and are valuable for understanding surface processes and landscape evolution. However, 10Be is usually measured in quartz minerals. Here we present advances in efficiently extracting and measuring 10Be in the pyroxene mineral. These measurements expand the use of 10Be as a dating tool for new rock types and provide opportunities to understand landscape processes in areas that lack quartz.