Using sedimentological priors to improve 14C calibration of bioturbated sediment archives.

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Authors

Bryan C. Lougheed 

Abstract

Radiocarbon (14C) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but current 14C calibration techniques applied to such age heterogenous samples were originally developed for age homogeneous material. A lack of information about age heterogeneity leads to a systematic underestimation of a sample's true age range, as well as the possible generation of significant age-depth artefacts during periods of highly dynamic Δ14C. Here, a calibration protocol is described that allows for the application of sedimentological priors describing sediment accumulation rate, bioturbation depth and temporally dynamic species abundance. This Bayesian approach produces a credible calibrated age distribution associated with a particular laboratory 14C determination and its associated sedimentological priors, resulting in an improved calibration, especially in the case of low sediment accumulation rates typical of deep-sea sediment. A time-optimised computer script (biocal) for the new calibration protocol is also presented, thus allowing for rapid and automated application of the new calibration protocol using sedimentological priors. This new calibration protocol can be applied within existing age-depth modelling software packages to produce more accurate geochronologies for bioturbated sediment archives.

DOI

https://doi.org/10.31223/X5N323

Subjects

Earth Sciences, Geology, Physical Sciences and Mathematics, Probability, Statistics and Probability

Keywords

radiocarbon, probability, palaeoceanography, calibration, bioturbation

Dates

Published: 2021-06-30 20:51

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
no new data was produced

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