You can load a rotation model (a
.rot rotation file) into GPlates then digitize a point on the stable part of South America (201) and then use the Kinematics Tool (
Utilities > Open Kinematics Tool) to display its velocity over time. Actually you don’t even need to digitize a point for this, you can just specify the latitude/longitude in the tool. You can then visualize the velocity magnitude or direction in the 2D graph, and export the velocity data to a CSV file.
If you also want to see this path on the globe you can digitise a
MotionPath feature (see Tutorial 2.3). You can also export the absolute velocity of the motion path in the Export dialog (
Reconstruction > Export, and then add export choosing Velocities and GMT), but first you’ll need to manually create a velocity layer and set it up (connect it to motion path layer and specify calculating velocity of
domain points as shown in image below). So in this case it’s probably easier to just use the Kinematics Tool.