Radiocarbon 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.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/623129 |
| Date | 31 January 2017 |
| Creators | Miyake, Fusa, Jull, A. J. Timothy, Panyushkina, Irina P., Wacker, Lukas, Salzer, Matthew, Baisan, Christopher H., Lange, Todd, Cruz, Richard, Masuda, Kimiaki, Nakamura, Toshio |
| Contributors | Department of Geosciences, University of Arizona, Arizona Accelerator Mass Spectrometry Laboratory, University of Arizona, Laboratory of Tree Ring Research, University of Arizona |
| Publisher | NATL ACAD SCIENCES |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | Copyright © 2016 The Authors. Published by National Academy of Sciences. |
| Relation | http://www.pnas.org/lookup/doi/10.1073/pnas.1613144114 |
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