ShellChron: Builds Chronologies from Oxygen Isotope Profiles in Shells

Takes as input a stable oxygen isotope (d18O) profile measured in growth direction (D) through a shell + uncertainties in both variables (d18O_err & D_err). It then models the seasonality in the d18O record by fitting a combination of a growth and temperature sine wave to year-length chunks of the data (see Judd et al., (2018) <doi:10.1016/j.palaeo.2017.09.034>). This modelling is carried out along a sliding window through the data and yields estimates of the day of the year (Julian Day) and local growth rate for each data point. Uncertainties in both modelling routine and the data itself are propagated and pooled to obtain a confidence envelope around the age of each data point in the shell. The end result is a shell chronology consisting of estimated ages of shell formation relative to the annual cycle with their uncertainties. All formulae in the package serve this purpose, but the user can customize the model (e.g. number of days in a year and the mineralogy of the shell carbonate) through input parameters.

Version: 0.2.8
Depends: R (≥ 3.5.0)
Imports: rtop (≥ 0.5.14), zoo (≥ 1.8.7), ggplot2 (≥ 3.2.1), ggpubr (≥ 0.4.0), tidyverse (≥ 1.3.0), tidyr (≥ 1.1.1), scales (≥ 1.1.0), dplyr, magrittr
Suggests: knitr, rmarkdown
Published: 2020-11-20
Author: Niels de Winter ORCID iD [aut, cre]
Maintainer: Niels de Winter <niels_de_winter at>
License: GPL-3
NeedsCompilation: no
Materials: README NEWS
CRAN checks: ShellChron results


Reference manual: ShellChron.pdf
Package source: ShellChron_0.2.8.tar.gz
Windows binaries: r-devel:, r-release:, r-oldrel:
macOS binaries: r-release: ShellChron_0.2.8.tgz, r-oldrel: ShellChron_0.2.8.tgz


Please use the canonical form to link to this page.