A HIGH-RESOLUTION C-14 DATED SEDIMENT SEQUENCE FROM SOUTHWEST SWEDEN - AGE COMPARISONS BETWEEN DIFFERENT COMPONENTS OF THE SEDIMENT

A macrofossil-rich glaciomarine-marine-lacustrine sediment from a soft -water lake in southwestern Sweden has provided an opportunity to C-14 date different components of its sediments. Bulk sediment dates are 1 00 to 500 yr older than fragile terrestrial macrofossils of correspond ing levels, with a mean age difference of ca. 300 yr. This is explaine d by the presence of old and reworked organic material in the sediment . Five age comparisons between terrestrial macrofossils and periostrac a of marine bivalves (probably Arctica islandica) of Allerod age give a mean age difference of 380 yr, i.e. slightly greater than the presen t reservoir age of 340 +/- 30 yr for the Swedish west coast. This diff erence is roughly the same as for the marine macroalga Desmarestia acu leata. A date from shell carbonate fragments of Mytilus edulis yields an age that is more than 1000 yr older than corresponding periostraca and terrestrial macrofossils and 500-1000 yr older than the age of the supposed deglaciation of the site. Altogether this indicates a larger marine reservoir effect during the Allerod than at present. (C) 1998 by John Wiley & Sons, Ltd.