WIP: unnamed Earh-like planet

[Pixie]

Groovey, your questions made me rethink some of my own conceptions about tectonics and plate movement and go back to the drawing board on my own "fiction planet". Thanks for that!
From start, I chose the ignore most the times that plates movement is always rotational around a fictional pole (called Euler pole). I thought for larger plates, the rotation would be very small and thus we could think about it linear terms. However, on second thought, that's not the case and it's very much the opposite. Large plates is actually where it makes a bigger difference. So, I looked around a little bit and found this interesting resources:

explaining euler pole
euler pole movement applied to the boundary between north american plate and pacific plate

I also thought of a way to picture this with PS (or Gimp):
- create a layer on top of the the map and place a solid color shape exactly fitting the plate you want to look at
- on another layer draw a little cross to mark the euler pole of that plate
- under <edit>, select the option rotate - a small cross with a circle appears in the middle of the selection
- move that circle to the position where you placed the cross and then rotate the shape
- this allows to experiment with the plate movement and to figure out where subduction, transform and crust formation is happening

(this is an extra effort to get things right and may or may not end up to be useful, I haven't quite experimented enough with it yet - I also suspect it won't work well on plates too close to the poles)

Now, as for your specific questions:

1. The direction where the subduction triangles are pointing indicate which plate subducts into which plate right? In my case, for example, plate 8 subducts into plate 9, and nº3 to nº1 (at least north of the boundary), is that right?

Yes, your blue triangles are in the correct positions.
Modern geology thinks collisions between continents are not exactly subduction, though, they just bend, fold and pile up, neither of the plates actually sinks.

For example, what I did in boundary of nº8 and 9, would subduction happen across ALL the boundary, or in some segments it wouldn't be subduction?

Is the boundary between plate nº7 and 3 indeed a transformation one? All through it?

Try that "rotation" trick I described above.. it will show you the right answer, I think.

Also, you have the tendency to place island chains in oceanic rifts. While there's a few islands and island chains along Earth's rifts, they don't generate the New Zealand size islands you have.

I think this version is a common (I got it now, it messed up what I had and now it's awful, it will come out much better on the next try). Keep ploughing away!

[ascanius]

Groovey, your questions made me rethink some of my own conceptions about tectonics and plate movement and go back to the drawing board on my own "fiction planet". Thanks for that!
From start, I chose the ignore most the times that plates movement is always rotational around a fictional pole (called Euler pole). I thought for larger plates, the rotation would be very small and thus we could think about it linear terms. However, on second thought, that's not the case and it's very much the opposite. Large plates is actually where it makes a bigger difference. So, I looked around a little bit and found this interesting resources:

explaining euler pole
euler pole movement applied to the boundary between north american plate and pacific plate

I also thought of a way to picture this with PS (or Gimp):
- create a layer on top of the the map and place a solid color shape exactly fitting the plate you want to look at
- on another layer draw a little cross to mark the euler pole of that plate
- under <edit>, select the option rotate - a small cross with a circle appears in the middle of the selection
- move that circle to the position where you placed the cross and then rotate the shape
- this allows to experiment with the plate movement and to figure out where subduction, transform and crust formation is happening

(this is an extra effort to get things right and may or may not end up to be useful, I haven't quite experimented enough with it yet - I also suspect it won't work well on plates too close to the poles)

I tried this out in gimp. It adds a whole lot of complicated. Depending on the rotation, I created divergent boundaries where I had none before. I kept this limited to only my largest plate but I realize that I have to be careful otherwise divergent boundaries would spring up all over the place.

I have a question about the Euler poles. From my understanding the Euler pole is an axis of rotation independent of the earth axis of rotation. It is around this axis that the a body moves across the surface of a sphere. Because it is circular the body would a some point reach it's starting position if no other bodies interfere.

on a flat surface couldn't this be shown with a simple compass, it won't be mathematically accurate but for the general idea it should work seeing that rotation is faster farther from an axis of rotation.

Or am I so completely off that it is better if I stop typing? I'm gonna stop typing.

[Pixie]

I tried this out in gimp. It adds a whole lot of complicated. Depending on the rotation, I created divergent boundaries where I had none before. I kept this limited to only my largest plate but I realize that I have to be careful otherwise divergent boundaries would spring up all over the place.

Yep, I am struggling with the same thing. In some cases the best solution is to change the shape of the plate a little. In other cases I think that local "divergence" is covered by the movement of the adjacent plates and not necessarily liked to new crust formation. In other cases, if you want a more one-direction sort of movement, it's a matter of moving the Euler pole away from the plate.

About your question about Euler poles and rotation. Yes, you could do it with a compass on a flat surface (if the map was an ortographic projection centered on the rotation axis). I say this not being the mathematical expert, which I'm not, but the guy who has been fiddling and reading around. From my experience, different projections give totally different areas of crust creation and crust subduction around a plate.