Using ice core measurements from Taylor Glacier, Antarctica to calibrate in situ cosmogenic 14C production rates by muons

• Main Authors: Dyonisius, Michael, Petrenko, Vasilii, Smith, Andrew, Hmiel, Benjamin, Neff, Peter, Yang, Bin, Hua, Quan, Schmitt, Jochen, Shackleton, Sarah, Buizert, Christo, Place, Philip, Menking, James, Beaudette, Ross, Harth, Christina, Kalk, Michael, Roop, Heidi, Bereiter, Bernhard, Armanetti, Casey, Vimont, Isaac, Englund Michel, Sylvia, Brook, Edward, Severinghaus, Jeffrey, Weiss, Ray, McConnell, Joseph
• Format: Text
• Language: English
• Published: 2022
• Subjects: Taylor Glacier; Antarc*; Antarctica; ice core
• Online Access: https://doi.org/10.5194/tc-2021-375; https://tc.copernicus.org/preprints/tc-2021-375/

Cosmic rays entering the Earth’s atmosphere produce showers of secondary particles such as neutrons and muons. The interaction of these neutrons and muons with oxygen-16 ( 16 O) in minerals such as ice and quartz can produce carbon-14 ( 14 C). Analyses of in situ produced cosmogenic 14 C in quartz are commonly used to investigate the Earth’s landscape evolution. In glacial ice, 14 C is also incorporated through trapping of 14 C-containing atmospheric gases ( 14 CO 2 , 14 CO, and 14 CH 4 ). Understanding the production rates of in situ cosmogenic 14 C is important to deconvolve the in situ cosmogenic and atmospheric 14 C signals in ice, both of which contain valuable paleoenvironmental information. Unfortunately, the in situ 14 C production rates by muons (which are the dominant production mechanism at depths of > 6 m solid ice equivalent) are uncertain. In this study, we use measurements of in situ 14 C in ancient ice (> 50 kilo-annum before present, ka BP) from the Taylor Glacier ablation site, Antarctica in combination with a 2D ice flow model to better constrain the rates of 14 C production by muons. We find that the commonly used values for muogenic 14 C production rates (Heisinger et al., 2002a, 2002b) in ice are too high by factors of 5.7 (3.6–13.9, 95 % confidence interval) and 3.7 (2.0–11.9 95 % confidence interval) for negative muon capture and fast muon interactions, respectively. Our constraints on muogenic 14 C production rates in ice allow for future measurements of 14 C in ice cores to be used for other applications and imply that muogenic 14 C production rates in quartz are overestimated as well.