Help with tectonics

[altasilvapuer]

I agree with thebax2k: a couple more plate collisions might be in order. Most of your plates seem to be like London drivers - moving at breakneck speed and missing each other by bare inches. (Or, at least, like my impression of said drivers over a week's stay!)

Then again, it's quite intriguing to think about a world where the plates all seem to be somehow spending much of their time sliding beside each other, rather than most of their time spreading & consuming, like Earth. Your world wouldn't have as much recycling of crust, I think, which is an interesting concept. Fossils would be found much older, landmasses would probably be pretty eroded, and it might even have a few interesting effects on the magnetic field and such, though I'm shakiest on that last one. I think that's more just convection in the mantle than the recycling of crust, now that I think about it.

Regardless, as they are now, I think you'd see a mountain chain or two between 16 and 15. When two oceanic plates collide, usually one of them is just slightly less dense and goes above the other, and you get strings of islands along the boundary. As the bottom plate breaks up and becomes part of the molten material underneath, lots of gases get trapped and cause magma to upwell through the plate on top, and it forms volcanic islands. At least, I think that's more or less it; I forget the specifics of it at the moment.

I think the strangest thing in your tectonics, to me, is the number of them going in the same direction: 18, 14, 8, 9, and 6, specifically. It seems a little unusual that they'd all move in the same direction. At least on Earth, I don't think more than two or rarely three plates move in the same direction, and then they seem to be more beside each other, rather than chasing. Then again, our tectonic knowledge comes from a whopping data pool of one planet, so we might know absolutely nothing. Have at it, and I can't wait to see more!


Also, as you go into later stages of this worldbuilding, you should check out Karro and Korba's respective world maps. They were one of the primary guides, artistically, that I used for representing all the worldbuilding data you need.
Karro's is here: http://www.cartographersguild.com/showthread.php?t=2463
Korba's is here: http://www.cartographersguild.com/showthread.php?t=4812

There's also that Climate cookbook lurking around here someplace that's invaluable for its help in this. Let me see if I still have it in my bookmarks. Ah, here it is: http://www.cix.co.uk/~morven/worldkit/climate.html

-asp

[Karro]

There are some good points made that I forgot to look at, in detail. You'll get your highest mountains when two continent-bearing plates smack together in head-on collisions. If one or the other is moving in a slightly different direction, the mountains are likely to be lower. Where plates are slipping past eachother, rather than colliding, you'll get an intense earthquake zone. And underwater plates colliding tend to produce island chains. Meanwhile, and ocean plate colliding with a continental plate will sometimes produce chains of islands just offshore of the mainland (like Japan).

Meanwhile if two plates are moving along together in the same direction (like 6 and 9) if we assume they're moving at different speeds, then at most the fault will be an earthquake zone and maybe some low hills. If the same speed... well... what's differentiating them as plates? Large mountain zone there will depend on collisions.

Then, if one plate is moving away from another, you'll either get trenches (under the sea) or rift valleys (on land).

One thing that I tried to do on my plates was consider not only the overall motion of the plate as a whole, but the motion of individual pieces of a plate, and the impact of other plates on the movement of any given plate, as well as the impact of subterranean magma flows (which I believe, being somewhat liquid, will follow the coriolis effect). So, I tried to have different forces tearing and pushing at the plates in different ways, and defined plate motion in roughly circular patterns.