A new (super 14) C calibration data set for the last deglaciation based on marine varves.

Abstract

Varved sediments of the tropical Cariaco Basin provide a new (super 14) C calibration data set for the period of deglaciation (10,000 to 14,500 years before present: 10-14.5 cal ka BP). Independent evaluations of the Cariaco Basin calendar and (super 14) C chronologies were based on the agreement of varve ages with the GISP2 ice core layer chronology for similar high-resolution paleoclimate records, in addition to (super 14) C age agreement with terrestrial (super 14) C dates, even during large climatic changes. These assessments indicate that the Cariaco Basin (super 14) C reservoir age remained stable throughout the Younger Dryas and late Allerod climatic events and that the varve and (super 14) C chronologies provide an accurate alternative to existing calibrations based on coral U/Th dates. The Cariaco Basin calibration generally agrees with coral-derived calibrations but is more continuous and resolves century-scale details of (super 14) C change not seen in the coral records. (super 14) C plateaus can be identified at 9.6, 11.4, and 11.7 (super 14) C ka BP, in addition to a large, sloping "plateau" during the Younger Dryas ( approximately 10 to 11 (super 14) C ka BP). Accounting for features such as these is crucial to determining the relative timing and rates of change during abrupt global climate changes of the last deglaciation.