Insights on muonic production of radiocarbon (14C) from ablating and accumulating ice sheets: revised production rates and improved estimates of 14C retention in firn

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dc.contributor.authorHmiel, Ben_AU
dc.contributor.authorDyonisius, MNen_AU
dc.contributor.authorPetrenko, VVen_AU
dc.contributor.authorSmith, AMen_AU
dc.contributor.authorBuizert, Cen_AU
dc.contributor.authorSchmitt, Jen_AU
dc.contributor.authorSeveringhaus, JPen_AU
dc.date.accessioned2023-04-17T01:10:58Zen_AU
dc.date.available2023-04-17T01:10:58Zen_AU
dc.date.issued2021-12-16en_AU
dc.date.statistics2023-01-27en_AU
dc.description.abstractIn situ cosmogenic Radiocarbon (14C) production from 16O occurs at Earth’s surface via three mechanisms: neutron-induced spallation, negative muon capture and fast muon interactions. The majority of in situ cosmogenic 14C investigations utilize the near-surface production in quartz for the determination of exposure ages where cosmogenic 14C production is dominated by spallation while near-surface muonic production represents a small correction factor in most analyses. In contrast, in situ cosmogenic 14C produced in the polar ice sheet lattice is dominated by the muonic mechanisms as a result of rapid burial from the surface in accumulation regions and extended exposure for centuries to millennia at depth before the samples are drilled and extracted from the ice sheet for analysis. Here we present two significant updates regarding the understanding of in situ cosmogenic 14C production in ice. First, measurements of ice >50ka ice 14C from Taylor Glacier are combined with an ice-flow model to find that the commonly used muogenic 14C production rates (Heisinger et al., 2002) are overestimated by factors of 5.7 (3.6-13.9, 95% CI) and 3.7 (2.0-11.9 95%CI) for negative muon capture and fast muon interactions respectively. Utilizing these revised production rates, 14C measurements of snow and ice are quantified in an ice accumulation region, finding only ~0.5% of in situ 14C is retained above the depth at which bubble closure occurs in the porous firn. Parameters are developed in a forward model to quantify the in situ cosmogenic component of accumulation zone ice core measurements and segregate them from the atmospheric component, thus expanding the utility of ice core 14C measurements for paleoclimatic reconstructions.en_AU
dc.identifier.articlenumberEP35F-1372en_AU
dc.identifier.booktitleAGU Fall Meeting Abstractsen_AU
dc.identifier.citationHmiel, B., Dyonisius, M., Petrenko, V. V., Smith, A. M., Buizert, C., Schmitt. J., & Severinghaus, J. P. (2021). Insights on muonic production of radiocarbon (14C) from ablating and accumulating ice sheets: revised production rates and improved estimates of 14C retention in firn. Paper presented to the AGU Fall Meeting 2021, New Orleans, Louisiana and Online, 13-17 December 2021. In AGU Fall Meeting Abstracts (Vol. 2021, EP35F-1372). Retrieved from: https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/852072en_AU
dc.identifier.conferenceenddate17 December 2021en_AU
dc.identifier.conferencenameAGU Fall Meeting 2021en_AU
dc.identifier.conferenceplaceNew Orleans, Louisiana and Onlineen_AU
dc.identifier.conferencestartdate13 December 2021en_AU
dc.identifier.urihttps://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/852072en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14890en_AU
dc.identifier.volume2021en_AU
dc.language.isoenen_AU
dc.publisherAmerican Geophysical Union (AGU)en_AU
dc.subjectCarbon 14en_AU
dc.subjectIceen_AU
dc.subjectDrill coresen_AU
dc.subjectMuon detectionen_AU
dc.subjectGlaciersen_AU
dc.subjectAntarctic regionsen_AU
dc.subjectQuartzen_AU
dc.titleInsights on muonic production of radiocarbon (14C) from ablating and accumulating ice sheets: revised production rates and improved estimates of 14C retention in firnen_AU
dc.typeConference Posteren_AU
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