Quantifying the marine radiocarbon reservoir effect for U.S. mid-Atlantic coastal waters
Abstract
The marine radiocarbon reservoir effect is an offset of 14C age between terrestrial and marine samples of the same calendar age due to delay in atmosphere-ocean exchange of CO2 and dilution with older deep waters. Currently, the global average marine reservoir age of surface waters is ~400 radiocarbon years. However, this value can differ regionally based upon climate, ocean circulation, and coastal morphology. Accurate quantification of the local marine reservoir effect is crucial in determining precise chronologies in paleoenvironmental studies that rely heavily on marine samples. This also requires samples collected live prior to the onset of extensive nuclear testing in the 1950s, which greatly increased atmospheric radiocarbon. Regional marine reservoir offset values (ΔR) are poorly known for the U.S. mid-Atlantic. Currently, there are only three specimens from New Jersey to North Carolina for which ΔR values have been calculated. The average marine reservoir correction for these samples is ΔR = 142 ± 34 years. To extend this database, we obtained 19 live-collected marine mollusks spanning coastal areas from New York to North Carolina from museum collections and submitted them for AMS radiocarbon dating. The calibrated 14C ages will be compared to the date of collection, ranging from 1884 to 1945, in order to determine ΔR values for each specimen. Historical maps of each sample location, showing the local physiographic settings at the time of collection, will improve knowledge of what factors control spatial variations of the regional marine reservoir effect.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMGC43D0974M
- Keywords:
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- 1105 GEOCHRONOLOGY / Quaternary geochronology;
- 1194 GEOCHRONOLOGY / Instruments and techniques;
- 1694 GLOBAL CHANGE / Instruments and techniques;
- 9350 GEOGRAPHIC LOCATION / North America