A Synthesis of Deglacial Deep-Sea Radiocarbon Records and Their (In)Consistency With Modern Ocean Ventilation
|Author(s)||Zhao Ning1, 2, Marchal Olivier3, Keigwin Lloyd3, Amrhein Daniel4, 5, Gebbie Geoffrey6|
|Affiliation(s)||1 : Massachusetts Inst Technol Woods Hole Oceanog Ins, Woods Hole, MA 02543 USA.
2 : Max Planck Inst Chem, Climate Geochem Dept, Mainz, Germany.
3 : Woods Hole Oceanog Inst, Dept Geol & Geophys, Woods Hole, MA 02543 USA.
4 : Univ Washington, Sch Oceanog, Seattle, WA 98195 USA.
5 : Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA.
6 : Woods Hole Oceanog Inst, Dept Phys Oceanog, Woods Hole, MA 02543 USA.
|Source||Paleoceanography And Paleoclimatology (2572-4517) (Amer Geophysical Union), 2018-02 , Vol. 33 , N. 2 , P. 128-151|
|WOS© Times Cited||23|
|Keyword(s)||last deglaciation, ocean ventilation, data synthesis, radiocarbon, inverse method|
We present a synthesis of 1,361 deep-sea radiocarbon data spanning the past 40kyr and computed (for C-14-dated records) from the same calibration to atmospheric C-14. The most notable feature in our compilation is a long-term Delta C-14 decline in deep oceanic basins over the past 25kyr. The Delta C-14 decline mirrors the drop in reconstructed atmospheric Delta C-14, suggesting that it may reflect a decrease in global C-14 inventory rather than a redistribution of C-14 among different reservoirs. Motivated by this observation, we explore the extent to which the deep water C-14 data jointly require changes in basin-scale ventilation during the last deglaciation, based on the fit of a 16-box model of modern ocean ventilation to the deep water Delta C-14 records. We find that the fit residuals can largely be explained by data uncertainties and that the surface water Delta C-14 values producing the fit are within the bounds provided by contemporaneous values of atmospheric and deep water Delta C-14. On the other hand, some of the surface Delta C-14 values in the northern North Atlantic and the Southern Ocean deviate from the values expected from atmospheric (CO2)-C-14 and CO2 concentrations during the Heinrich Stadial 1 and the BOlling-AllerOd. The possibility that deep water 16-box records reflect some combination of changes in deep circulation and surface water reservoir ages cannot be ruled out and will need to be investigated with a more complete model.