Updated Cariaco Basin14C Calibration Dataset from 0–60 cal kyr BP

Konrad A Hughen,Timothy J Heaton

doi:10.1017/rdc.2020.53

Abstract

ABSTRACTWe present new updates to the calendar and radiocarbon (14C) chronologies for the Cariaco Basin, Venezuela. Calendar ages were generated by tuning abrupt climate shifts in Cariaco Basin sediments to those in speleothems from Hulu Cave. After the original Cariaco-Hulu calendar age model was published, Hulu Cave δ18O records have been augmented with increased temporal resolution and a greater number of U/Th dates. These updated Hulu Cave records provide increased accuracy as well as precision in the final Cariaco calendar age model. The depth scale for the Ocean Drilling Program Site 1002D sediment core, the primary source of samples for14C dating, has been corrected to account for missing sediment from a core break, eliminating age-depth anomalies that afflicted the earlier calendar age models. Individual14C dates for the Cariaco Basin remain unchanged from previous papers, although detailed comparisons of the Cariaco calibration dataset to those from Hulu Cave and Lake Suigetsu suggest that the Cariaco marine reservoir age may have shifted systematically during the past. We describe these recent changes to the Cariaco datasets and provide the data in a comprehensive format that will facilitate use by the community.

Highlights

Calibration of the 14C timescale over its full length has advanced remarkably in recent decades
Marine Reservoir Age Comparing the newly updated Cariaco Basin 14C dataset to Hulu Cave 14C in Figures 5 and 6, both plotted under the assumption of a constant level of marine reservoir age (MRA)/dead carbon fraction (DCF) 14C depletion, does reveal several periods where apparent offsets exist, mostly consisting of younger 14C ages for the Cariaco Basin data
The 14C calibration data set from intermittently varved sediments of the Cariaco Basin has been substantially updated, with changes to calendar and 14C chronologies

Summary

Introduction

Calibration of the 14C timescale over its full length has advanced remarkably in recent decades. To incorporate the Cariaco 14C record into IntCal20, changes in the MRA for the Cariaco Basin through time were modeled as an additive spline and estimated during curve construction by comparison with all of the other constituent IntCal20 datasets (Heaton et al 2020a in this issue).

Results

Conclusion