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Geomagnetic field control of 14 C production over the last 80 Ky: Implications for the radiocarbon time‐scale
Author(s) -
Mazaud A.,
Laj C.,
Bard E.,
Arnold M.,
Tric E.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/91gl02285
Subject(s) - radiocarbon dating , earth's magnetic field , dipole , geology , environmental science , magnetic field , physics , paleontology , quantum mechanics
We have used a recent estimate of the geomagnetic dipole field strength over the last 80 ky to examine the extent to which changes in geomagnetic field intensity have affected the radiocarbon time scale. The magnetic record was converted into a 14 C production signal which was then used to produce a synthetic atmospheric Δ 14 C record using a two box model for the carbon cycle. This calibration suggests that the geomagnetic field has been the main factor governing the production of cosmogenic 14 C atoms over the period of time considered, and that Δ 14 C changes due to other causes, such as climatic changes, have been of lesser importance. The results indicate that the radiocarbon ages are 2 to 3 ky younger than true age in the interval 18–40 ky b.p., in good agreement with recent U‐Th and 14 C age comparisons. Moreover the results predict that a negligible difference between true and 14 C ages should be observed around 45–50 ky.