GeoModels

GeoModels is a collection of paleogeography models for historical biogeography.

Basic details of the models

Pixelation

The models are build using an equal area isolatitude pixelation: Earth is divided in latitude rings, and each ring is divided according to its circumference, using the size of a pixel in the equatorial ring. Each pole has its own pixel, and odd numbered rings has a half pixel offset for the starting pixel. The pixel IDs start at 0 in the North Pole, and then increased by one, starting at the Sunday-Monday line in west-east direction. This pixelation is implemented in the earth package.

Resolution is indicated using the form e<Number>, with the number being the number of pixels in the equatorial ring. For example e360 is a pixelation with 360 pixels at the equatorial ring.

Identification

Each general model is kept in its own repository, usually the files are identified by the name of the model, the kind of file, the spatial resolution, and time resolution. For example earthbyte-motion-360-5.tab is the plate motion model of the earthbyte model, with a e360 pixelation, and a time steps of 5 million years.

Model types

There are two kind of models: plate motion models and paleolandscape models.

A plate motion model is identified as *-motion-*.tab and contains the pixel location at different times. Note that as a pixelation is used, sometimes a present pixel might be represented by two or more pixels in the past. On the other hand, it is possible that several present pixels might be set in the same pixel in the past. This motion model is also know as a rotation model, because it is based on Euler rotations over a sphere.

A paleolandscape model is identified by its model name and contains pixel values (a landscape identifier) at different times. In this case pixel identities across different time periods are not preserved. To ease identification of the pixel values a key file identified with *-key.tab is provided for each paleolandscape model.

Paleolandscape models are associated with a particular plate motion model. To make them more general, unrotated paleolandscape models are also provided, so they can be used in combination with any rotation model. This models are identified as *-landscape-unrot-*.tab files, and should be rotated before using.

Additionally, a plate pixel model is identified as *-pixels-*.tab and is used to link pixels with tectonic plate.

Models

Plate motion models

Model	Main reference	Pixelation	Time frame	Time step	Paleolandscape
EarthByte	Müller et al. 2019	e360, e180, e120	400 - 0	5	Cao et al. 2017
Kocsis and Scotese 2021	Kocsis and Scotese 2021	e360, e180, e120	540 - 0	5	Kocsis and Scoteses 2021
Muller et al 2022	Müller et al. 2022	e360, e180, e120	540 - 0	5	Cao et al. 2017 (400-0); Scotese and Wright 2018 (405-540)
PaleoMap	Scotese 2016	e360, e180, e120	540 - 0	5	Scotese and Wright 2018
NoMotion	Public domain	e180, e120	4500 - 0	--	Natural Earth

The NoMotion model is an static Earth model with present geography.

Unrotated paleolandscape models

Model	Main reference	Pixelation	Time frame	Time step
Cao et al 2017	Cao et al. 2017	e360, e180, e120	400 - 0	5
Kocsis and Scotese 2021	Kocsis and Scotese 2021	e360, e180, e120	540 - 0	5
PaleoMap	Scotese and Wrigth 2018	e360, e180, e120	540 - 0	5

Citation and data license

The models in the collection are processed from the ones provided by their original authors. As such, the original publication should be cited when the model is used. In each model, the relevant papers are given in a README file, and provided as BibTeX.

It is not required to cite this repository, but if you do not include the model in the supplementary material of your publication, it might be a good idea to link this repository and help others to replicate or re-use your analysis.

Building your own model

To build your own model, it is expected that you build it previously on GPlates. The file(s) containing the plate features must be in GPML format (do not use the compressed gpmlz). The rotation file must be a rot file.

The process uses the command plates that is included in the earth package.

Import a plate motion model

First, transform all the tectonic features files into pixel files. For example to read the file contient.gpml to produce continent.tab, a pixelation file with 360 pixels at equator:

plates pixels import -e 360 -o continent.tab continent.gpml

If yo have multiple pixel files, you can merge them:

plates pixels cat -o pixels.tab continent.tab volcanic.tab

To check that pixelation is right you can make an image of the pixelation:

plates pixels map -o pixels.png pixels.tab

After pixelation is build, you can make the rotation, defining the starting time and time steps, or a predefined series of time stages. For example here we make the file model.tab from the pixels that we build before, from 420 million years, in 5 million years time stages, and using rotations.rot rotation file:

plates rotate --from 420 --step 5 --pix pixels.tab --rot rotations.tab model.tab

Import a paleolandscape model

There are several forms to build paleolandscape models.

To transform a plate motion model into a paleolandscape model use the command timepix add, if no time frame is indicated, the plate motion model time frame will be used. For example using the plate motion model at model.tab to create a paleolandscape model timepix.tab with the value of 1:

plates timepix add --from 400 --in model.tab --val 1 timepix.tab

In the case of only a unique time slice is to be added, use the flag --at. In this example, we add the pixels of the model sea-rot.tab to paleolandscape model timepix.tab at 100 million years with the value of 2:

plates timepix add --at 100 --in sea-rot.tab --val 2 timepix.tab

In some cases, for example the Cao model included in Earthbyte, a GPML files contains layers at different time stages, with different polygons to be rotated at a particular time stage. In such cases, first we must make the pixelation, then rotate the pixelation model, and finally add the pixels. For example adding pixels from lm.gpml with a value of 3 at 120 million years to the paleolandscape model at timepix.tab:

plates pixels import -e 360 --at 120 -o lm-pix-120.tab lm.gpml
plates rotate --pix lm-pix-120.tab --rot rotations.rot lm-rot-120.tab 120
plates timepix add --at 120 --in lm-rot-120.tab --val 3 timepix.tab

In other case you have a mask image file (a black and white image, only white pixels will be used). In this example, we add pixels from the mask mask-lowsea.png with a value of 2 in the present time to the paleolandscape model at timepix.tab:

plates timepix add --at 0 -f mask --in mask-lowsea.png --val 2 timepix.tab

Rotating a paleolandscape model

To rotate a landscape model use the command timepix rotate, and give the rotation model you want to use:

plates timepix --model motion-model.tab --output landscape.tab landscape-unrot.tab

In which motion-model.tab is a plate motion model, landscape-unrot.tab is an unrotated paleolandscape model, and landscape.tab is the output model using the plate motion model.

To make an unrotated model, just use the flag --unrot:

plates timepix --model motion-model.tab --unrot --output landscape-unrot.tab landscape.tab

Note that many paleolandscape models are developed with a particular plate motion model, so many landscape features will be lost in the rotations, if the landscape feature can not be matched with a pixel corresponding to a current tectonic plate. For example, in the collision of India and Asia, it is usual to add land between India and several Tibetan terranes. Then, this rotated paleolandscapes should be used not as final paleolandscapes, but as starting points of a paleolandscape reconstruction.

js-arias/geomodels