[Tutorial] Using GPlates to model continental drift

[Charerg]

There’s been a number of ambitious world-building projects recently that have attempted to model tectonic movements in a fictional world. One program that is extremely useful in creating a functional tectonic model for this purpose is GPlates, which allows you to model continental drift across time on a globe. As there aren’t any comprehensive GPlates tutorials on the guild, I thought I’d write one.

Note: This isn’t a tutorial about plate tectonics, only about how to use GPlates to model the movements of the continents. To actually figure out which movements make sense and which don’t, you need to familiarise yourself with plate tectonics.

Requirements for this tutorial:
GPlates

GPlates' own user documentary and tutorials:
Link

Before I begin with the tutorial itself, I should note that I’m not going to cover the basic functions of GPlates (like moving the view). However, there are some existent tutorials by Astrographer that cover this, which I recommend:
Using gplates for Realistic Worldbuilding
Continental Drift the gplates Way


Here are the contents of the tutorial planned so far. I’ll probably keep expanding this over time with more sections.

1. Basic functionality: creating and moving continents
   
   a. Creating a continent
   b. Writing a rotation file
   c. Animating the continental drift
   
   
2. Advanced functionality: locating mid-oceanic ridges and creating oceanic crust
   
   a. Creating flowlines
   b. Creating oceanic crust
   c. Colouring the oceanic crust based on age
   
   
3. Advanced functionality: using Motion Paths to trace hotspots
   
   
4. Advanced functionality: checking plate velocity
   
   
5. Advanced functionality: generating a velocity field
   
   
6. Advanced functionality: using conjugate plates

Each section will be posted in a separate post (once it’s been written), and linked to the above table of contents. Without further ado, on to the tutorial itself!

[Charerg]

a. CREATING A CONTINENT

So, first off, the basics. Open GPlates, choose File->Save Project As and then create a new folder for your GPlates model, and save the project there. Assuming that you’ve familiarized yourself with the basic functions like moving the view (Drag Globe, hotkey D) and changing projections, we can get started with creating your first continent. To begin with open the “Digitisation tools” (hotkey 3). There are three options: digitise point, line and polygon geometry. For drawing the outline of a continent, we want to “Digitise new polygon geometry (hotkey G)”:

Sample 01.PNG

Go on drawing the outline point-by-point. Once you’ve finished click “Create feature”. Now a list will open where you’ll pick what type of feature you’re creating. Choose either ClosedContinentalBoundary or ContinentalCrust as the feature type and click next.

Sample 02.PNG

In the next window, we will name the feature we’ve created, define when it exists, and which Plate ID it belongs to. The Plate ID 0 represents the planet’s spin axis in GPlates (and should be kept immobile). Since we want our continent to move, pick a different Plate ID (100 in this example). For the “time of appearance”, pick a point far in the planet’s past (500 Mya in the example) and 0 Mya (present) for the “time of disappearance”.

Sample 03.PNG

Then click next. Another window will pop up, but we don’t need to touch anything there, so click Next. Then, create a new feature collection called “Continents” where you’ll save this feature (as well as other similar features) and save it in your project folder.

Sample 04.PNG

Btw, ignore that "Landmass" feature in the screenshot (it's an artifact from the tutorial writing, you shouldn't have it). You’ve now created your first continent, congratulations! Next, let’s give it some colour. First, download the following image and save it in your project folder.

Primordial Continent Mass.png

Then, choose File->Import->Import raster and import the image you just loaded into GPlates. GPlates will ask about which longitudes and latitudes the raster covers. Since the above image already has the proportions of an equirectangular projection, the default settings are fine. GPlates will now generate a new feature collection from the loaded image in the folder where your image is located (which is why we saved it in the project folder to keep things organised). Now you should have the raster in your layer manager (Window->Show layers if you’ve closed it):

Sample 05.PNG

Open the raster, and under the “Inputs” tab, find “Reconstructed polygons” and choose “Continents”. Now your raster should only affect the features defined in the “Continents” feature collection.

Sample 06.PNG

Now you’ve created your continent and attached a raster image to it. This is very useful with existing maps, since you can import them as rasters and then draw the continent outlines over the image. If you tie the raster to a feature like we did here, it will also follow the movements of the continent. Speaking of said movements, the next step is to get the continent we just created moving. For that, we need a rotation file.



b. WRITING A ROTATION FILE

All motions in GPlates are defined as a rotation around an Euler pole, and relative to a conjugate plate. For that, you need to separately create a text file called the “rotation file”. I recommend using Notepad++ for this.
So, create a simple text file called “rotation” and copy the following there:

100 0.0 90.0 0.0 0.0 000 !Plate A
100 2000.0 90.0 0.0 0.0 000 !Plate A

All entries in the rotation file have this format. The different columns have the following meaning:

Plate ID	Time	Latitude	Longitude	Angle	Conjugate plate	Comment
100	0.0	90.0	0.0	0.0	000	Plate A

This row describes the position of plate 100 at 0.0 Mya. The latitude and longitude describe the position of the Euler pole, the angle describes the rotation around it, while the conjugate plate tells us that this rotation is relative to plate 000 (which is the planet’s spin axis). So, in this case the Euler pole is the North Pole. The rotations can also be described relative to other plates, but for now we’ll keep this simple and keep the rotations relative to the planet’s spin axis.

The good news is that you won’t actually have to calculate any of this stuff yourself. GPlates can automatically modify the rotation file once you’ve set it up. To do that, we just need to do what we just have: define the plate’s position at present and at some arbitrary point far away in the past. Ideally, both of these “boundary rotations” should be kept at [90, 0, 0] values (or [0, 0, 0], but in that case GPlates automatically rewrites it to [90, 0, 0] anyway).

So, for now all we need to do is to just copy the lines I gave into a text file. Make sure there is an empty line at the end of the file, otherwise it may not work properly. Then save it as “rotation.rot”. With Notepad++, you can do this by choosing “All types” and manually typing .rot as the file type.

Rotation file sample I.PNG

Now that you have your rotation file, open your GPlates project and choose File->Open feature collection and open the rotation file you just saved. The rotation file should now be in your feature manager (File->Manage feature collections to check), and you’re all set for getting your continent moving!



c. ANIMATING THE CONTINENTAL DRIFT

Now we’re ready to get your continent moving. First off, pick a point in the past (type on the Time window), say 150 Mya. Then open the “Pole manipulation” tools (hotkey 5). “Choose feature (hotkey F)” and pick the continent you just created. You’ll note that it’s still in its present-day location. Next, pick “Move pole (hotkey O)”, and check “Enable pole”. There should now be an arrow representing a pole at the location of the north pole of the planet.

Sample 07.PNG

This is the pole that you'll rotate your continent around when you define its new location. The Move pole tool allows you to drag it around. Once you are happy with where the pole is located, pick “Modify reconstruction pole (hotkey P)”. Now you can drag the outline of the continent around the pole.

Sample 08.PNG

Fiddle around with the location of the continent (you can move the pole around too), and once you’re happy, click Apply. This will create a new reconstructed rotation for the continent in the rotation file at 150 Mya. However, it still needs to be saved, so open your Feature manager (File->Manage feature collections) and save the rotation file. Now you can click “Play” and see how your continent moves from the location you just defined into its present-day location!

However, your continent looks a bit lonely right now. To give it a pal, let’s try that other method of drawing a continent. Download the following picture and import it into GPlates as a raster, just like you did in the earlier parts of this section.

Continent B.png

Depending on how the layers are ordered in the layer manager, your planet should look something like this:

Sample 09.PNG

If you need to, you can hide some layers by clicking the eye icon in the layer manager. Set your “Time” back to 0.0 Mya and draw the outline of a new continent from the imported raster, just like you did previously. Then create it as a new feature (as before). Remember to give it a different Plate ID than Plate A (200 in this example), and save it in a new feature collection (say, Continents II), because we want to use a separate raster image for it than continent A.

Sample 10.PNG

Again, open your layers manager, open the layer corresponding to the “Continent B” raster, then under input click reconstructed polygons and pick “Continents II” (or whatever name you gave to the new feature collection). Your planet should now look like this:

Sample 11.PNG

Now, you need to set up your rotation file to include a separate plate for the continent we just created. First, File->Manage feature collection and make sure you’ve saved the rotations you made previously in GPlates. Then, open the rotation file in a text editor, and “set up” plate B, just like you did previously. Your rotation file should look something like this:

Rotation file sample II.PNG

Now that you’ve modified your rotation file, you need to reload it into GPlates. Open your “Manage feature collections” window again, and click the action “Reload” for the rotation file (the recycle icon).

Sample 12.PNG

Now, we can create our ancient supercontinent. Move back to 150 Mya in time and arrange continents A and B into a single continent. The result might look something like this:

Sample 13.PNG

As you can see, the fit isn’t quite perfect. However, we can fix that. Let’s say you’re really happy with continent B and don’t want to change the shape, so we’ll redraw continent A to fit the model. Basically, just redraw continent A like you’ve done previously, only now do so in 150 Mya. Remember to save the newly created continent A with the Plate ID 100 and save it in the right feature collection ("Continents").

Sample 14.PNG

The new outline of the continent should now appear, and you can delete the old one. So, your supercontinent might look something like this:

Sample 15.PNG

Then you can play the animation and see the continents breaking apart. A few example pics from this:

75 Mya:
75 Mya.PNG

0 Mya:
0 Mya.PNG

As you can see, these movements are a bit clunky and overlap a little. You can keep adding new reconstruction poles to new dates and so forth to get the movements right. You could also change the location of the continents in the present day by giving them “non-zero” present-day rotations. However, this should be avoided since it can mess up some of the more advanced features of GPlates (we’ll get to those later). So, that’s it for the first section of this tutorial! You’ve now learned how to create and move continents in GPlates. Give yourself a pat in the back and prepare for more to come, since in the next section we'll proceed into more advanced stuff: modelling the location of mid-oceanic ridges and the creation of new oceanic crust.

This my first tutorial here at the Guild, but I hope everything was clear and understandable. If you have any comments, questions, or ideas about the tutorial, feel free to post them. I'll try to keep track of this thread and answer them as time permits. Oh, and the 2nd section should be up "soonish" so stay tuned !

[Todd Spengo]

This looks awesome, thanks!


Sent from my iPhone using Tapatalk

[kacey]

Thank you so much! This is so helpful and easy to understand, I only wish you had of posted it earlier. It took me a long time to figure out this much on my own with the lack of good tutorials and I'm still lost on how to find the ridges and oceanic crust so I'm really excited for the next part because I have all but given up on figuring it out on my own...

This couldn't have come at a better time.

[Charerg]

Thank you so much! This is so helpful and easy to understand, I only wish you had of posted it earlier. It took me a long time to figure out this much on my own with the lack of good tutorials and I'm still lost on how to find the ridges and oceanic crust so I'm really excited for the next part because I have all but given up on figuring it out on my own...

This couldn't have come at a better time.

Actually some of your troubles were kind of useful when writing the tutorial. It's been a few years since I learned the basics myself, so I've totally forgotten the kind of hurdles I came across as a beginner, and would have totally missed the stuff about Notepad++ and saving as .rot, if I was just writing this from my own "point of view", so to speak. So one might say that your suffering wasn't entirely in vain .

[Warlin]

I think a lot of people here in the guild were waiting for your tutorial, Charerg. Thanks for that. Will keep an eye on your progress .
Cheers.

[Charerg]

a. CREATING A FLOWLINE

Okay, so now that we have our continents separating, it’s time to look at modelling the new oceanic crust being created as part of the process. We’re going to use the flowlines feature of GPlates to achieve that, but before we start with the actual modelling it’s worthwhile to take a closer look at the behaviour of mid-oceanic ridges.

First off, a mid-oceanic ridge generates new oceanic crust at equal rate on both sides of the ridge. This has some implications for the movement of the mid-oceanic ridge that I’ll now try to demonstrate with a few pics taken from the model used in the GPlates tutorials (based on Seton et al. 2012).

First off, I’ve drawn the initial location of the India-Antarctica rift (130 Mya):
130 Mya.png

And then look at where the present-day ridge is located. You can still see ”the original location” close to where the Kerguelen plateau is.
0 Mya.png

As you probably noted, there is a rather substantial discrepancy between the location of the initial rift and the present-day location of the mid-oceanic ridge. That is because the distance between a point in India and Antarctica that were once connected is about 9000 km. Of this distance Antarctica has covered 1500 km, and India 7500 km (very rough Google Maps measurements btw, nothing official). However, the ridge has created 4500 km of new crust both on the Antarctic and Indian plates. What this means in practice, is that the ridge has migrated 3000 km northwards due to the difference in relative movement between India and Antarctica. Well, actually the reality is a bit more complicated than that in this case, since the ridge in question became extinct around 40 Mya (the extinct mid-oceanic ridge between Indian and Australian plates today is the one initially located between India and Antarctica). Also, a good chunk of that ridge has now been subducted by Eurasia (so maybe not the best example). But you catch my (continental) drift, eh?

Since I think it’s somewhat intuitive to think of mid-oceanic ridges as static, fixed features I feel the above point needed to be made. The ridges are in fact not static at all, they move depending on the relative motions of the plates. So, we need some method to the track the movement of these ridges, and that’s where flowlines come in.

Here, I’ve created a flowline between South America and Africa:
0 Mya Atlantic.png

Again, note the “white outline” showing the location of the initial rift and note the discrepancy between its location and the modern ridge.

Here’s a second image, this time showing the actual present-day ridge as well:
0 Mya Atlantic Ridge.png

As you’ll note, the flowline isn’t an exact match (I wasn’t too careful with point placement), but it does approximately match the shape and location of the mid-oceanic ridge. Also, the flowlines should depict the orientation of the “stretch marks” on the ocean floor, which is an additional useful feature of them.

The previous image with a global gravity anomaly raster on top:
0 Mya Stretch Marks.png

Right, so after that rather long-winded introduction, let’s jump pack to our previous fictional model, and actually create one of these vaunted flowlines. First off, set the Time back to the point when the supercontinent starts breaking. Before you start, be aware that creating flowlines can cause crashes if you pick the wrong option or something goes wrong. So always save everything before attempting to create a flowline.

After you’ve made sure everything is saved, go under the Digitise tools and choose “Digitise multi-point geometry (Hotkey M)”. Go ahead and place some points at the seam between the two continents. Once you’re happy, click Create feature and choose Flowline from the list.

Sample B1.PNG

Then, click Next and you will be presented with some options. First off, you have the choice between spreading centres, left-plate end points and right-plate end points. Now, this is the critical option for those crashes I mentioned. I believe left-plate end points and right-plate end points are intended to work with plates. And plates in GPlates are not defined using the Digitisation tools, instead they are defined with the Topology tools (which we haven’t covered yet). This is why in the previous section we chose either ClosedContinentalBoundary or ContinentalCrust as feature type for our continents. Note that in Astrographer’s tutorial one suggestion was to define the continents as ClosedPlateBoundary. I wouldn’t recommend this, and it may cause problems with the flowlines we’re attempting to create here.

So, in case you didn’t guess it yet, choose spreading centres, otherwise I can almost guarantee you’ll get a crash. Then, type the appropriate Plate IDs in the “Left Plate ID” and “Right Plate ID” slots, set the flowline to exist from 150 Mya to present, and give it an appropriate name.

Sample B2.PNG

Next, you’ll have to insert an array of time instants. The flowline calculates the “half-stage rotations” between the two continents at specific intervals, and now you’ll have to define what those intervals are. Click “Add” and then under “Insert multiple times”, set it to insert times from 150 to 0 Mya at 10 Mya intervals. Then click “Insert” and “Ok”.

Sample B3.PNG

Click next and create a separate feature collection called “Flowlines” for storing flowline features. If your GPlates is going to crash, it will do so now (okay, it shouldn’t crash as long as you remember to pick spreading centres). Assuming everything went fine, you should now have a nice new feature collection. Go ahead and play the animation, to see the flowline in action. For me, this is the end result:

Sample B4.PNG

As you can see by looking at the flowline, something is dreadfully wrong with my rotations here. Apparently, I have a “hinge type rotation” with the hinge in the middle of the ocean! You’ll note that flowlines are a good way to check if your movements are valid, or if they’re total nonsense like my animation here. One way to fix this (in this case), is to redraw Continent A at present:

Sample B5.PNG

Then I can fiddle with the rotations a bit, and again redraw the continent at 150 Mya to fit the supercontinent. In this case, I originally redrew the continent at 0 Mya instead of rotating it to avoid giving it a “non-zero” present-day rotation (which will partially mess up flowlines 100% of the time). Flowlines do sort of “auto-update” to changes in rotation, btw. That said, you might have to re-create the flowline if you change continent shapes and location substantially or add a lot of new rotations. After some further redrawing and changing rotations (and recreating the flowline, several times in this case), here’s the result:

Sample B6.PNG

Note that I added a few pieces of extra crust to both continents here. You can do that by simply digitising a new polygon, just as we did when drawing the continent outlines. Then simply give it the same Plate ID as the parent continent, and it will stick along. Also, in this case save it in the same feature collection as its parent to give it the same texture. Now, looking at the flowline we see that the movements actually make sense! Note that since those “arrows” along the flowline are generated at 10 Mya intervals, you could directly estimate from this the ages of the oceanic crust, as well as the location of the mid-oceanic ridge!

However, if you want your GPlates model to not only be functional, but also to look pretty, you might want to actually depict the creation and aging of the oceanic crust. The further sub-sections will cover this process (and will fortunately be much shorter as well).



b. CREATING OCEANIC CRUST

Right, moving on to drawing the continental crust that is created at the mid-oceanic ridge. This is actually a very simple process, but somewhat time-consuming. Basically, the crust needs to be drawn manually. Now, don’t panic, this is actually fairly quick with the help of that flowline we created earlier. The “time-consuming” part comes in because it needs to be done separately for different ages. Which is why you should only consider doing this once your rotations are finished (at least for the two particular continents breaking apart)!

So, first off you need to decide at which intervals you’re going to draw the “new slabs” of oceanic crust. To keep this quick and simple, I’m going to draw them at 50 Mya intervals in this case. So, I need to draw one at 100 Mya (depicting the crust 150-100 old), the next at 50 Mya and a final slab at 0 Mya. So, first set the Time to 100 Mya. Then simply “Digitise new polygon geometry”, just like you did when drawing the continents, and draw the slab of oceanic crust using the flowline as an indicator. If you want to do this quickly, just click from point-to-point along the flowline. If fancy, you can think about where the strike-slip faults should be located based on the shape of the ridge, and put some “zig-zag” there. Those strike-slip faults (the “stretch marks” we noted earlier) should have the same orientation as the flowline, btw. Once you’re happy, “Create feature” and pick OceanicCrust as the type.

Sample Bb1.PNG

Then give it the appropriate Plate ID so it follows the right continent, name it and specify that this slab appears at 100 Mya:

Sample Bb2.PNG

Next, go ahead and click through the final windows and save this in a new feature collection called “Oceanic Crust”. This is important because we want to colour this separately from the continents. Once done, you need to do what you just did for the slab connected to the opposite continent as well, of course. Just remember to give that the Plate ID of the other continent (200 in this case) and save in the feature collection we just created. This is how my continent looks like afterwards:

Sample Bb3.PNG

That done, we can move on 50 Mya. Since this is a tutorial, I’m now going to show you the “quick and dirty” way to draw those slabs faster. Normally, I would of course never consider such underhanded shenanigans, and would draw each slab down to the smallest strike-slip fault. But, you can directly click the flowline (using the “Choose feature” tool), and click “Copy geometry to digitise tool” to automatically copy-paste the points of the mid-oceanic ridge. Outlined in red in the following image:

Sample Bb4.PNG

Then you can just switch to “Digitise new polygon geometry” and finish the outline. Go ahead and create the 50 Mya slabs in this fashion. Again, be careful to give them the right Plate ID and specify that the new slabs appear at 50 Mya. Also, remember to save them in the Oceanic Crust feature collection. This is how the result looks like for me:

Sample Bb5.PNG

And finally, switch to 0 Mya and draw the final slabs. Again, remember the right Plate IDs and specify the time of appearance as 0 Mya. Having done this in the “quick and dirty” way, this is how my crust looks like:

Sample Bb6.PNG

As you can see, it doesn’t look too pretty yet, just the outlines. And if we wanted just the outlines we could have used the “quick and dirty” method to copy the points of the mid-oceanic ridge at various intervals and saved those as lines using “Digitise new polyline geometry (hotkey L)”. So, let’s go ahead and colour it, shall we?



c. COLOURING THE OCEANIC CRUST BASED ON AGE

To colour the oceanic crust we just created, open your Layers manager, and find the Oceanic Crust feature collection. Under “Reconstruction options” check “Fill polygons”. You might want to also set the “Fill opacity” at 0.5, so the flowlines are still visible.

Sample Bb7.PNG

Next, choose Features->Manage Colouring and a new window pops up which lets you to manage the colouring of your various layers. This is pretty useful for other features besides oceanic crust as well, btw. From “Select layer”, choose “Oceanic Crust” and then pick FeatureAge and Default. The result:

Sample BB-8.PNG

If you play the animation, you can now view new oceanic crust popping up, and the colour changes as it ages. Congratulations, you’ve managed to complete this section of the tutorial!

I should note that this method works best for Atlantic-type situations, where an ocean has two passive margins. For other situations, it’s more tricky, but the method is the same. For example, if you have an ocean with an active and passive margin (meaning the crust is subducted on the other side of the ocean), you’d need to create a sort of “ghost plate” to depict the movements of the subducted crust. Say, create a piece of oceanic crust, give it a unique Plate ID and then use it as an “anchor” for the flowline. Those plates will have to be “set up” in the rotation file, of course. Since it’s going to be tricky to specify the present-day location of these kinds of essentially random slabs, it’s probably best just to terminate the flowline at say, 1.0 Mya (or before) to avoid the need to fiddle with “non-zero” present-day rotations. Here’s a quick example I just made:

150 Mya:
150 Mya.png

100 Mya:
100 Mya.png

50 Mya:
50 Mya.png

Remember that flowlines auto-update to rotation changes, so they’re very useful when attempting something like this. In fact, a good “workflow” is to first set up just initial basic rotations, then make use of flowlines to get them right, inserting new rotations and what-not. However, while with these methods we can already get pretty believable movements, we don’t have any clue yet if the velocities of our plates are plausible at all. Next up, I’m going to quickly cover the use of motion paths to create hotspot tracks (they’re very similar to flowlines), and then we’ll look at some methods to find out the velocity of your plates.

[Tiluchi]

So glad this is up now Charerg! Though of course it means many more hours for me wasted on GPlates... but fun hours!

[Charerg]

Okay, this section is going to be a quick one. First off, open your model and set the time back to 150 Mya. Go under the Digitise tools, and choose ”Digitise new multi-point geometry”. Then simply place a point where you wish a hotspot to be located 150 Mya, Create feature and choose MotionPath.

C1.PNG

Then choose a name for the hotspot and specify time of appearance (150 Mya in this case). Set the Plate ID as that of the plate that will be travelling over the hotspot, and leave Relative Plate ID at 0 (the planet’s spin axis).

C2.PNG

Next, insert an array of time instants from 150 to 0 Mya at 10 Mya intervals, just as you did with the flowline.

C3.PNG

Click next and save the motion path in a new feature collection called “Hotspot Trails”. Normally, the motion path will be coloured according to the Plate ID we gave it. I recommend changing the colour, in order to make it more visible (changing the colours of feature collections was covered in Section 2c). Now, go ahead and play the animation. For me, this was the result:

C4.PNG

As you’ll note, the trail is quite different from the flowlines. This is because motion paths represent the absolute motion of a plate relative to a fixed point on the globe, whereas the flowlines depict the relative motion between two plates. Also, with motion paths it’s good to remember that the arrows point away from the present-day position of the point. As you can see, this feature is extremely useful for tracing hotspot trails!

That’s it for this section! You’ve now covered the essentials, and already have the tools to make pretty good use of GPlates. However, in case you want to go the extra mile, and not only want your continents to move, but also want them to move at plausible speed, next I’ll cover how you can check the velocities of your continents.

[Charerg]

We now have our continents moving and fresh oceanic crust being formed along the way. In most cases, the actual velocity of the pieces probably isn’t as important as the movements themselves, but since there’s an easy way to check the velocity in GPlates, might as well do that.

First off, the velocity of plate movement is different depending on which point within the plate you’re standing on. The velocity of Eurasia would be different in Europe than in Asia. So, all the velocity values you see in this post are measured at a particular point. However, for any velocity measurements regarding our fictional continents and plates to be actually useful, we need some yardstick to compare them to. So, it’s time to look at Earth and the speed of real tectonic plates. The Wikipedia plate tectonics map includes the present-day velocities of Earth’s plates relative to Africa (Link).

While the wiki map is a very good resource, ideally we’d want the velocities to be measured relative to the planet’s spin axis and an average over a wider timeframe rather than just present-day velocities. With that in mind, I’ve compiled a haphazard list using the model supplied in the GPlates tutorials (based on Seton et al. 2012). The following list includes the average velocities of various plates from 50-0 Mya, including the approximate region where the velocity is measured. All these velocities are relative to the planet’s spin axis (Plate 0 in GPlates). Note that I’ve used just 5 Mya steps here to make my calculations quicker, so this is just supposed to give you a rough idea, these aren’t scientific-level accurate.

Plate (Region)	50-0 Mya Avg. Velocity [cm/year]
North American (Texas)	3.1
South American (Amazon Basin)	3.1
African (Kongo Basin)	1.9
Antarctic (South Pole)	1.2
Australian (Lake Eyre)	5.0
Indian (Deccan)	6.3
Eurasian (Tibetan Plateau)	1.5
Eurasian (Ukraine)	1.6
Pacific (Hawaii)	7.5
Nazca (Galapagos)	8.9

The “speed record” is made by India 55 Mya (18.7 cm/year in this model), which might be seen as a maximum velocity of sorts (it’s far from the average though). Remember that the above values are long term averages, the velocity could be drastically different during a shorter period. Since this is a GPlates tutorial, not a plate tectonics tutorial, I won’t go too deep into why the plate speeds vary, but here are a few rules:

1. Plates that are being subducted (slab pull) move swiftly (Indian, Australian, Pacific, Nazca)
2. Plates made of oceanic crust tend to move faster, especially if being subducted (Pacific, Nazca)
3. Plates largely surrounded by divergent boundaries are slow (African, Antarctic)
4. Large plates predominantly made of continental crust tend to move slowly (Eurasian)
5. Continent-continent collisions slow the continents involved (African, Eurasian)
6. Plates that are subducting oceanic crust and made of about 50/50 continental/oceanic crust fall in the middle (the American plates)
7. Smaller plates tend to move faster than large plates (Nazca, Indian, Australian)

Okay, I think that’s enough background material to get us started. So, let’s fire up our fictional model. Let’s say we want to know the velocity of Continent A. First, “Choose feature” and pick Continent A. Then, Utilities->Open Kinematics Tool.

D1.PNG

Click “Use focussed feature” to show the kinematics for our selected feature (Continent A). Then, set the “Begin” as 150 Mya (since this is when our supercontinent starts breaking apart). You can also set the “Step” to be what you want. I set it at 10 Mya in this case. Then, choose “Velocity magnitude” as the Display Type in order to get a graph about the feature’s velocity at the specified coordinates. Speaking of said coordinates, if you want to pick a specific point, you can hover your mouse over it to check what the coordinates are, and then type those in the kinematics tool. The “mouse coordinates” are outlined in red in the following pic:

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And here we can directly see that Continent A has a relatively slow velocity of 1.3 cm/year. And checking Continent B, it’s even slower, crawling at 0.7 cm/year! So, we can directly see here that my continent movements are considerably slower than what they probably should be in this case (damn those slowpokes).

As a warning example, I’ve made a continent here that crosses about a quarter of the globe in 20 million years:

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You can see that the “speedo-meter” is flashing red right now. Better watch out that you don’t have one of these scoundrels cruising around in your model, there’s penalties for going too fast ‘round this neighbourhood! Remember, the Tectonics Police is watching!