WIP: help with tectonics

[Traven]

Hello, I've been lurking on here for a while now but this is my first time really posting. I hope I'm in the right place.
I've been having problems with my plate tectonics and am looking for some constructive criticism on my attempt. One of my biggest headaches is the fact that I have the shape of the land done first and am trying to make the plates match the continents and ocean basins as opposed to plates first and land after. The reason for this is that the map has evolved form previous maps that were made long before I was even considering going this detailed, but I can't delete the land and start over because I have it just the way I want it and starting over would waste years of world building.



This is my current plate arrangement. I left out the land because I would like the plates, their shape, and their movement critiqued without knowledge the the shape of the land.

Thank you

[Iggy]

It is no issue to drawn landmass first then drawing the tectonic plates, providing you are willing to modify your landmass should the plates and the theory behind it demand it. I have done the same for my world map after taking extensive time reading about tectonic plates from various sources and the current result stems me mildly optimistic. Should you desire one here is a good world map and the tectonic plates drawn on it.

It is also difficult to judge your tectonic plate drawing, let alone read it, without seeing the landmass created by it. But of course I'm merely speaking for myself here.

[Treijim]

I'm new to this sort of thing, but I don't think your antarctic plate makes sense. If you imagine a vertical equator (whatever that's called) then if it's moving north on one side of the world, it can't move north on the other side unless it's pulling itself apart. Your south plate seems to be spiralling into itself.

In the bottom middle you have two tiny plates. I believe that red line is only for when plates pull apart from one another, yet it seems the two small ones are static and they are being half pushed against, half slid past. That needs fixing.

Most of your red boundaries (ridges?) seem to not make sense. Those things really only happen in the direction the plates pull. Your arrows and lines seem a little half-hearted. I can't FEEL the tectonic movement by looking at it, yet a map like this of earth has all the movement in it. It's all in the lines.

[Traven]

Thanks for your comments.
Here's what what it looks like on the map


Iggy: I know it would be hard to judge without seeing the land, I just wanted to know if the plates themselves made sense.

Treijim: You're not incorrect about the southern plate, it's just because of the projection. The middle part (center, "closer" to viewer) is moving south and outside part (on the other side of the world) is moving north. Here's an image of what it looks like looking at the south pole.


About the two small plates at the bottom middle. They're not static, I just forgot to put the arrows. And they're not really two separate plates, it's one plate moving east to west but the northern and southern halves are moving at different speeds, creating a transform fracture fault (similar to the North American and South American, or Eurasian and African plates moving away from the mid Atlantic ridge).
Most of my spreading zones don't make sense? How so exactly?
I'm not sure what you mean that you can't "feel" the movement.

Thanks for your replies.

[Treijim]

I changed a few plates. It's all about the direction of arrows, the direction of divergent (red) intersecting lines, and the angles of the plate boundaries.

Your antarctic plate was primarily connected via divergent boundaries. This only happens when there are two plates, and two arrows, moving directly away from one another. Now you have three main divergent movements, because there are only three main instances where your tectonic arrows are moving directly away from one another. The smaller intersecting red lines always move in the direction of the arrows.

I changed a lot of your boundaries to transform boundaries, indicated by a plain (yellow) line. These only occur when the arrows are "rubbing" against one another, moving in opposite directions but only adjacently and not head-on as with convergent boundaries.

Then there are convergent (subduction) boundaries, where one plate slides under or crumples against another. Since most of your subduction happens at sea, it's less likely to crumple and more likely to overlap. They occur ONLY when the plates meet head-on and the arrows are moving directly against one another. So I added more of those; there's a lot of collision happening in this world of yours.

Some of your connections are a little tricky still, such as the few boundaries just west of your tiny double plates, between the two south-reaching landmasses. The tectonic movements there seem vague at best still. But the other transform boundaries should make more sense. There's also a bit of confusion where the four south-east most boundaries meet.

In terms of feeling the movement, it's a matter of the direction of the lines. On earth, you can trace tectonic movements using huge lines that cover half the world. The plates are all broken apart, but they move in a way that is sort of strangely graceful. It's hard to describe, and might not feel like a helpful comment, but I think if you keep tweaking your tectonic plates and movements (try flipping and rotating your image for a fresh view now and then) you'll make it look more convincing. If any of my suggestions don't make sense or you disagree, please let me know so I can explain why I did what I did. Good luck.