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 seasonalityin the d18O record by fitting a combination of a growth and temperature sine wave to year-length chunks ofthe data (see Judd et al., (2018) <doi:10.1016/j.palaeo.2017.09.034>). This modeling is carried out along a sliding window through the data and yields estimates ofthe day of the year (Julian Day) and local growth rate for each data point. Uncertainties in both modelingroutine and the data itself are propagated and pooled to obtain a confidence envelope around the age ofeach data point in the shell. The end result is a shell chronology consisting of estimated ages of shellformation relative to the annual cycle with their uncertainties. All formulae in the package serve thispurpose, but the user can customize the model (e.g. number of days in a year and the mineralogy of theshell carbonate) through input parameters.
| Version: | 0.4.0 |
| Depends: | R (≥ 3.5.0) |
| Imports: | rtop (≥ 0.5.14),zoo (≥ 1.8.7),ggplot2 (≥ 3.2.1),ggpubr (≥ 0.4.0),tidyr (≥ 1.1.1),scales (≥ 1.1.0),dplyr,magrittr |
| Suggests: | knitr,rmarkdown |
| Published: | 2021-07-05 |
| DOI: | 10.32614/CRAN.package.ShellChron |
| Author: | Niels de Winter [aut, cre] |
| Maintainer: | Niels de Winter <niels_de_winter at live.nl> |
| BugReports: | https://github.com/nielsjdewinter/ShellChron/issues |
| License: | GPL-3 |
| URL: | https://github.com/nielsjdewinter/ShellChron |
| NeedsCompilation: | no |
| Materials: | README,NEWS |
| CRAN checks: | ShellChron results |
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