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Readme file for seafloor age grid files
for 0-410 Ma topological plate reconstructions
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Contents:
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This folder contains sets of seafloor age grids for various, GPlates-compatible
tectonic reconstructions.
- Matthews et al (2016), https://doi.org/10.1016/j.gloplacha.2016.10.002
- Young et al (2019), https://doi.org/10.1016/j.gsf.2018.05.011

The precise versions of the reconstructions files used are included in the
directories along with the seafloor age grids. They differ from the original
models in fixing a bug in Pacific motions
https://www.earthbyte.org/gplates-2-2-software-and-data-sets/

The grids are generated using the code described in
- Williams et al (2020), https://doi.org/10.1016/j.gsf.2020.06.004

The source code used to generate the grids is available in two locations:
1. An archive of the original code used to generate results in Williams et al (2020)
is available here (compatible with python 2.7):
https://zenodo.org/record/3271360#.X0Hl2xMzZDY

2. The latest version with updates for use with python 3 is available here:
https://github.com/siwill22/agegrid-0.1


Grid formats:
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- The grids are provided in netcdf-4 format. These can be read with a range of
  open-source software including GMT, QGIS, and Panoply
- Grids are provided at 0.5 degree resolution and in 1 Myr increments. Alternative
  resolutions can be derived using the input files and source code as listed above,
  or contact the authors.
- The grids can also be loaded into GPlates and viewed as a time-dependent raster
  sequence.


Known Issues:
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While the grids provide a good first-order mapping of the seafloor age distributions
at global scale, they also contain numerous likely small-scale artifacts arising from
input reconstructions. Typically, these manifest as unusually high ages around the
edges of large ocean basins, or within small basins where the level of detail of the
reconstruction is insufficient. Where subduction zones 'jump' between successive
time-steps, small fragments of old seafloor become trapped inboard of the new subduction
geometry. Removing these artifacts in detail requires the reconstruction files to be
modified. While such issues have neglible influence of gross characteristics of the
seafloor ages, care should be taken when relying on values directly adjacent to
continental margins.


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Contact:
simon.williams@nwu.edu.cn
dietmar.muller@sydney.edu.au