Publication Date:
2018
Description:
〈p〉Paired measurements of 〈sup〉14〈/sup〉C/〈sup〉12〈/sup〉C and 〈sup〉230〈/sup〉Th ages from two Hulu Cave stalagmites complete a precise record of atmospheric 〈sup〉14〈/sup〉C covering the full range of the 〈sup〉14〈/sup〉C dating method (~54,000 years). Over the last glacial period, atmospheric 〈sup〉14〈/sup〉C/〈sup〉12〈/sup〉C ranges from values similar to modern values to values 1.70 times higher (42,000 to 39,000 years ago). The latter correspond to 〈sup〉14〈/sup〉C ages 5200 years less than calibrated ages and correlate with the Laschamp geomagnetic excursion followed by Heinrich Stadial 4. Millennial-scale variations are largely attributable to Earth’s magnetic field changes and in part to climate-related changes in the oceanic carbon cycle. A progressive shift to lower 〈sup〉14〈/sup〉C/〈sup〉12〈/sup〉C values between 25,000 and 11,000 years ago is likely related, in part, to progressively increasing ocean ventilation rates.〈/p〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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