Independent verification of age tie points and planktic reservoir ages deduced for two marine sediment records at the Chilean continental margin by 14C plateau tuning

On the basis of ¹⁴C plateau tuning we established a robust centennial-scale age control for last glacial-to-deglacial sediment sections in two marine sediment cores MD07-3088 and PS97-137 from the upper Chilean continental margin to facilitate a precise stratigraphic correlation between short-term changes in South Pacific oceanography and global paleoclimate signals recorded in ice cores from Antarctica and elsewhere (Küssner et al., in prep.). Age tie points and reservoir ages were derived from tuning a suite of planktic ¹⁴C plateaus to a suite of pertinent atmospheric ¹⁴C plateaus defined at Lake Suigetsu (Sarnthein et al., 2015). Off central Chile four tephra layers in Core MD07-3088 provide independent proof both for the age assignment and for short-term changes in planktic reservoir age we deduced by means of ¹⁴C plateau tuning. Reservoir ages derived from ¹⁴C plateau tuning at 11–16.5 cal. ka closely match, one-by-one, four reservoir ages that have been deduced from the difference between the ¹⁴C ages of planktic foraminifera associated with the tephra layers in marine sediments and the atmospheric ¹⁴C ages of plants associated with paired tephras analyzed nearby on land (Siani et al. 2013). – In Core PS97-137, near to the southern tip of Chile, sediments of the Last Glacial Maximum show a section with distinct lamination of 5-7 layers / cm depth, associated with atmospheric ¹⁴C Plateau 6a by plateau tuning. A rough count of the layers in the 160 cm long sediment section of the planktic ¹⁴C Plateau 6a gives a number that comes extremely close to the ~900 year-long time span of the atmospheric ¹⁴C Plateau 6a, thus provides independent proof for both the accuracy of the time interval assigned to correlated atmospheric ‘Plateau 6a’ and the approach of plateau tuning in general.

 

Küssner et al., Paleoceanography, in prep.,

Sarnthein et al., Radiocarbon, 2015, 57 (1), 129–151.

Siani et al., 2013, Nature comm., 4, 2758.