Large 14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene
Jull, A. J. Timothy
Panyushkina, Irina P.
Baisan, Christopher H.
AffiliationDepartment of Geosciences, University of Arizona
Arizona Accelerator Mass Spectrometry Laboratory, University of Arizona
Laboratory of Tree Ring Research, University of Arizona
MetadataShow full item record
PublisherNATL ACAD SCIENCES
CitationLarge 14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene 2017, 114 (5):881 Proceedings of the National Academy of Sciences
RightsCopyright © 2016 The Authors. Published by National Academy of Sciences.
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AbstractRadiocarbon content in tree-rings can be an excellent proxy of the past incoming cosmic ray intensities to the Earth. Although such past cosmic ray variations have been studied by measurements of 14C contents in tree rings with ≧10 year time resolution for the Holocene (1), there are few annual 14C data. There is a little understanding about annual 14C variations in the past with the exception of a few periods including the AD774-775 annual 14C excursion (2). Here, we report the result of 14C measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1-2 year resolution, and a finding of an extraordinarily large 14C increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The 14C increase rate of this event is much larger than that of the normal Grand Solar Minima. We propose the possible causes of this event are a special phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.
VersionFinal accepted manuscript
SponsorsJapan Society for the Promotion of Science (JSPS) [26887019, 16H06005]; JSPS [G2602]; Toyoaki Scholarship Foundation