SEDIMENTATION RATE VARIABILITY FROM A GLOBAL DATABASE OF RADIOCARBON DATED OCEAN SEDIMENT CORES

Understanding the variability of sedimentation rates in the deep ocean (>1000m depth) can have a large influence on the interpretation of paleoclimate records from ocean sediment core data. In particular, estimates of the timing and rate of change for abrupt climate events often rely on interpolation of ages between age measurements, such as radiocarbon dates or tie-points. A better estimate of sedimentation rate variability could improve uncertainty estimates for these interpolated ages. Lin et al., 2014, previously examined sedimentation rate variability in deep sea sediment cores using radiocarbon dates from 37 cores with sedimentation rates > 8cm/kyr. Here we re-examine their estimates of sedimentation rates by 1) including the effects of radiocarbon, calibration and reservoir age uncertainty; 2) comparing the measured sedimentation rate variability of cores with a mean sedimentation rate both greater than and less than 8cm/kyr; and 3) exploring the influence of changing the resolution of radiocarbon dates on sedimentation rate variability estimates. Preliminary results using 54 cores with sedimentation rates > 8cm/kyr, but which are mostly distinct from those in the original study, closely resembles the mixed-log normal distribution described by Lin et al., 2014, suggesting the result is robust to both uncertainty and the dataset used. However, our results from 50 cores with a mean sedimentation rate < 8cm/kyr show a narrower distribution in sedimentation rate variability. Although these lower sedimentation rate cores have a lower average resolution for radiocarbon dates, analysis so far suggests that this lower variability is not an artifact of lower sampling resolution. These new results can provide guidance for age-depth modelling in ocean sediment cores and improve age uncertainty estimates in paleoclimate time series.