GeoModels is a collection of paleogeography models for historical biogeography.
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.
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.
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.
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.
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 |
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.
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.
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
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
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.