Glacial to deglacial reservoir ages of surface waters in the southern
Ocean sediment records document abrupt changes in glacial-to-deglacial
circulation and mixing of the ocean, recorded as changes in
14C reservoir ages of surface waters.
Here we present 14C-based high-resolution age records
of four sediment cores derived by means of 14C plateau
tuning. This provides a detailed and precise stratigraphic correlation
between the western and eastern South Pacific and paleoclimate records
of Antarctic ice cores as well as 14C reservoir ages.
The accuracy and precision of plateau tuning are confirmed in two
sediment cores off Chile; in one core by independent land-based age
control of four tephra layers, in a second core by a suite of glacial
sediment varves. During glacial times, high reservoir ages reaching up
to ~1500 yr may reflect
seasonal sea ice and/or a melt water lid at high latitudes both east of
New Zealand and off southern Chile and may be linked to northward
advection of upwelled old subsurface waters from the Polar Frontal Zone.
Our results support the model of a bipolar seesaw at the onset of rapid
deglacial Antarctic warming, moreover, they show that the Antarctic Cold
Reversal immediately preceded the onset of the Younger Dryas cold spell.