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Media type:
E-Article
Title:
Correlation of Marine 14C Ages from the Nordic Seas with the GISP2 Isotope Record: Implications for 14C Calibration Beyond 25 ka BP
Contributor:
Voelker, Antje H. L.;
Sarnthein, Michael;
Grootes, Pieter M.;
Erlenkeuser, Helmut;
Laj, Carlo;
Mazaud, Alain;
Nadeau, Marie-Josée;
Schleicher, Markus
imprint:
Cambridge University Press (CUP), 1997
Published in:Radiocarbon
Language:
English
DOI:
10.1017/s0033822200018397
ISSN:
0033-8222;
1945-5755
Origination:
Footnote:
Description:
<jats:p>We present two new high-resolution sediment records from the southwestern Iceland and Norwegian Seas that were dated by numerous <jats:sup>14</jats:sup>C ages up to 54 <jats:sup>14</jats:sup>C ka bp. Based on various lines of evidence, the local <jats:sup>14</jats:sup>C reservoir effect was restricted to 400–1600 yr. The planktic stable isotope records reveal several meltwater spikes that were sampled with an average time resolution of 50 yr in PS2644 and 130 yr in core 23071 during isotope stage 3. Most of the δ<jats:sup>18</jats:sup>O spikes correlate peak-by-peak to the stadials and cold rebounds of the Dansgaard-Oeschger cycles in the annual-layer counted GISP2 ice core, with the major spikes reflecting the Heinrich events 1–6. This correlation indicates large fluctuations in the calibration of <jats:sup>14</jats:sup>C ages between 20 and 54 <jats:sup>14</jats:sup>C ka bp. Generally the results confirm the <jats:sup>14</jats:sup>C age shifts as predicted by the geomagnetic model of Laj, Mazaud and Duplessy (1996). However, the amplitude and speed of the abrupt decrease and subsequent major increase of our <jats:sup>14</jats:sup>C shifts after 45 <jats:sup>14</jats:sup>C ka bp clearly exceed the geomagnetic prediction near 40–43 and 32–34 calendar (cal) ka bp. At these times, the geomagnetic field intensity minima linked to the Laschamp and the Mono Lake excursions and confirmed by a local geomagnetic record, probably led to a sudden increase in cosmogenic <jats:sup>14</jats:sup>C and <jats:sup>10</jats:sup>Be production, giving rise to excess <jats:sup>14</jats:sup>C in the atmosphere of up to 1200%.</jats:p>