Glacial to deglacial reservoir ages of surface waters in the southern South Pacific

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 from the western and eastern continental margins of the South Pacific. Global correlation of centennial-scale ocean variability requires centennial-scale precision in age control which can be established by means of 14C plateau tuning. The accuracy and precision of plateau tuning are now 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 peak glacial sediment varves. The results from the cores support the model of a bipolar seesaw at the onset of fast deglacial Antarctic warming, moreover, they show that the Antarctic Cold Reversal immediately preceded the onset of the Younger Dryas cold spell. During peak glacial times, high reservoir ages reaching up to ~1500 yr and paired ice-rafted debris and sediment laminations may reflect seasonal sea ice and/or a melt water lid at high latitudes off southern Chile, likewise east of Southern New Zealand.