Friday, 9 September 2005 - 2:20 PM

This presentation is part of: Reservoir Age Variability in the Marine Environment

CHANGES OF SEA- SURFACE 14C RESERVOIR AGES IN THE MEDITERRANEAN SEA AND NORTH ATLANTIC OCEAN IN THE INTERVAL 2000-15,000 Cal yr BP

Martine Paterne, LSCE, Bat 12 Campus CNRS, Gif sur Yvette, 91198, France, Jacques-Elie Brochier, Economies, Sociétés et Environnements Préhistoriques, 5, rue du Château de l’Horloge, AIX-en-Provence 13094, France, and Maurice Arnold, LMC14, Bat 450 Porte 4E, CEA Saclay, Gif sur Yvette, 91191, France.

A series of 14C dating was derived from 43 paired charcoals and mollusc shells collected in archaeological caves from the Mediterranean region in order to reconstruct past changes of sea- surface 14C reservoir ages (Rsurf). The terrestrial (atmospheric) 14C ages were then converted into calendar ages using Calib 4.3, as, by contrast to the INTCAL Calib 5.04 version, the high frequency variability is preserved in this calibration. Then the marine Δ14C values were calculated and compared to those determined from the Cariaco basin series (Hughen et al., 2004) and from the Barbados corals (Bard et al., 1998 ; Fairbanks et al., 2005). Sea-surface reservoir ages and Δ14 calculations were similarly done for 46 paired charcoal/mollusk shells from mid to high latitudes of the North Atlantic Ocean.

Only 65% of the Mediterranean samples are reliable for such a reconstruction. The Mediterranean Rsurf vary from 200 yrs to 700 yrs, while the pre-anthropogenic mean value is about 390 years (Siani et al., 2000). The lower Mediterranean Rsurf are observed at around 10,000 Cal yr BP and 6,500 –7,500 Cal yr BP. The Atlantic Rsurf vary between 200 years to 600 years, except at 11,500 CAL yr (Bjork et al., 2001) and at ~12,000 CAL yr (Bard et al., 1994, Grönvold et al., 1995). In the interval 2000-8,000 Cal yr BP, the Mediterranean and North Atlantic Δ14C values are either similar or slightly larger than the terrestrial-derived marine Δ14C INTCAL 4.3 record. One exception occurs between 4000 Cal yr BP to ~ 5400 Cal yr BP where the Δ14C values are lower by some 30‰ with respect to the marine INTCAL record. In the interval 8,000_15,000 Cal yr BP, the Δ14C values of the Mediterranean and North Atlantic mollusc shells match closely the Cariaco and Barbados one's, and some of the Mediterranean Rsurf changes occurred at the time of rapid fluctuations of the atmospheric/marine 14C content.


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