Radiocarbon calibration of a high resolution core from the Central Arctic Ocean
2008 (English)In: EOS Transactions: American Geophysical Union, 2008, PP51A-1483 p.Conference paper (Other academic)
The big challenge in calibrating radiocarbon dates to calendar years for Arctic Ocean deep sea sediments is to estimate the marine reservoir age of the water masses. Most sediment cores from the central Arctic Ocean have a low resolution and the preserved record for the last 25 ka is in the order of 10-20 cm. Therefore, most AMS 14C dating results are presented either uncalibrated or corrected. The used reservoir values often vary between 400 and 550 years, close to the global mean ocean reservoir age, since all available regional reservoir differences (ΔR) are from coastal areas around the Arctic Ocean. Our study presents 14C ages and calibration attempts with different modelled reservoir ages from a high resolution record of Holocene and Late Glacial sediments from the Lomonosov Ridge. During the 2005 Healy-Oden Trans-Arctic Expedition (HOTRAX) an area of the central Lomonosov Ridge, between about 88°15’–89°N and 140°–180°E, was cored where a >1000 m deep depression characterizes the ridge morphology. Calcareous nannofossils (Fornaciari and Backman in prep.) and foraminifera analyzed in the upper 70 cm of core HLY0503-18TC show a sequence of the last ~130 ka. The chronology has been established through the nannofossil record in the lower 30 cm (Fornaciari and Backman in prep.) and 14C dating in the upper 40 cm. The data indicate very high accumulation rates during the Late Glacial of ~10 cm/ka, and times of extremely low to no accumulation during the Last Glacial Maximum, MIS 4 and parts of MIS 5. In addition, 14C dating on benthic and planktonic foraminifera from the same depth in the sediment core reveals age differences between surface and deep water masses. The age difference of such benthic-planktonic pairs shows a succession of ~1200 year older bottom watera in the Late Glacial to ~250 year in the late Holocene. This indicates circulation and/or ventilation changes through the last deglaciation and Holocene, which we hopefully will be able to date in greater detail with better model estimates of temporal changes in marine reservoir ages.
Place, publisher, year, edition, pages
2008. PP51A-1483 p.
IdentifiersURN: urn:nbn:se:su:diva-15021OAI: oai:DiVA.org:su-15021DiVA: diva2:181541