Help With Plate Tectonics?

I'm working on my conworld's geography, and I'd like some help figuring out the plate tectonics. My rough draft of the planet's geological history is available through this link.

The outlines roughly represent the outlines of the continents as they are in the modern day (neglecting the bits that emerged in the meantime). I used a program called gplates to construct these outlines, as well as to create the rough geological history I have now.

However, this only really describes the continental drift of the planet; I want to figure out the underlying plate tectonics, for two reasons:

• To figure out where the volcanic islands, earthquakes, and oceanic trenches are.
• To see if there are any problems with my depiction of my world's continental drift.

So, anything you can tell me about my world's plate tectonics? I'd really appreciate it.

edited 23rd Mar '15 5:38:18 PM by MysteryMan23

I suggest taking a look at the "Ring of Fire" string of volcanoes and seismic spots to possibly comparing it to your world.

Nat. Geo. Description

I'm gonna try and do this continent by continent plate by plate. The colors are hard to differentiate in a couple cases so bear with me if it seems confusing. I wasn't a Geology major in college but I do have it as a little bit of a hobby.

For this post I'm going to critique three plates.

• The Arctic Plate Analogue (Green one, top): Ok by what mechanism is it colliding with the Eurasian Plate Analogue (Red) and yet growing in size? Obviously it's a seafloor spreading zone that's fracturing and rifting along the EPA which would wonder why hasn't it rifted off at least some of Red? Even better, where's the islands off the coast that are forming? I'm guessing it's a multiple plate region not unlike the Amur/North American/Eurasian/Kuroshio (Japan) Plate region in reality, the mechanics of which in actuality aren't fully studied. Secondly once the ARPA fully breaks away what mechanism causes it to shrink before it collides with the North American Plate Analogue? If it's a multiple plate region that part of the planet would have either some huge ass island arcs and archipelagos (and their associated uberly deep undersea trenches) or outright subcontinents having formed from accretion of island arcs and some badass continuous volcanism in that part of the world. Thirdly when the ARPA heads toward the NAPA it shrinks and yet collides at the same time before growing again. Typically in plate tectonics that kind of collision eventually destroys a plate, for example the ancient Farallon Plate is almost completely subducted under North America, it's only known remnants besides accreted islands and island arcs in places like California are the Juan De Fuca plate off the US Pacific Northwest and Western Canada and the Gorda Plate near the same, and the Cocos and Nazca Plates off Central America. In time even those pieces will be completely subducted and/or otherwise consumed and destroyed geologically speaking. As a final note there'd be some hellacious mountain building and possible volcanism in the lead up and collision of the ARPA remnants and the NAPA in that particular region.
• The Eurasian Plate Analogue (Red, easterly) would under normal circumstances obviously be a stable craton. Since it expands from the middle obviously there was an attempted rifting going on mid-continent that failed to separate the plate. This would leave a rift valley geologic province dominated by old volcanism (possibly still active) and igneous rock among other things. Now late in your timeline the EPA starts shrinking in your easterly regions. Obviously it hit a tectonic boundary and is either subducting under a continent (NAPA?) or is an oceanic island arc and that part of the plate is undersea and has been for some time possibly since its creation. Alternatively it's a place of massive continental collision like going on with the Indian and Eurasian Plates in the Tibetan Plateau/Himalayan Mountains regions. If it's not colliding with the boundaries of the NAPA, what is it colliding with? Beyond that there's not much else to think about except that easternmost region will either be some massive mountain ranges in both height, width and breadth or if the undersea mechanics hold true it's gonna be a deep ass trench with some island arcs and archipelagos on the other side.
• The North American Plate Analogue (Purple, westerly, known as NAPA above) is likely an ancient but long lasting craton. Some extensional rifting and transform faulting (kinda like San Andreas in southern California) in the Northwest of NAPA aside there would be very little activity for most of it. It would geographically either a massive plateau and/or a huge vast region of open plains. Now if the theory above about the EPA crashing into the NAPA is correct, the western regions of the NAPA will be analogous to modern North America and very mountainous, possibly volcanic. The mountainous part is triply so if it is a continent on continent collision as opposed to the EPA being oceanic that far east. The eastern part of the NAPA would have some serious transform faulting where the Appalachians would be and would be smushed up mountains to the north where the ARPA is crashing in. It would also turn into a rift valley and shallow sea where the Caribbean Plate Analogue (Other green/gray) breaks away. A small mountain ridge would also form west of "Maine" when the Atlas Mountain Fragment (gray, tiny piece) meets up with the NAPA after rifting away from the Africa Plate Analogue (Yellow, center) rather bizarrely. West of that is obviously an extensional region as it's stretching the NAPA west to east. The AMF would also form a peninsula not entirely unlike present day Kamchatka.

I'll do more tomorrow.

I don't think the top green plate is growing : it looks like a projection deformation, due to it approaching the pole.

Yup, that's pretty much it! I actually just animated a view of my world's north pole. It's right here.◊

It looks like the oceans surrounding the green plate could contain islands like Hawaii or the Canary islands - IRL, an opening ocean frequently contains such.

Okay, so I've finally found the Media Uploader, and I have a rough draft of my planet's actual tectonic plates, and their interactions. Here it is:

The yellow lines represent the plate boundaries (except at the edges of the image; those are just artifacts). The blue arrows represent divergent and convergent boundaries; I haven't yet decided where the transform boundaries are.

Anyways, I'd like some feedback on this map. What did I do right, wrong, etc.? (Also, how do I get the image and text on different lines? I'm still new to uploading images here.)

edited 6th Apr '15 1:32:04 PM by MysteryMan23

What are the non-yellow lines? And I am not sure if the poles work.

The non-yellow lines are basically the continents and fragments thereof from my earlier maps. I literally created the plate boundaries on top of my earlier map.

Also, could you elaborate on your problems with the poles? Thank you.

There seems to be seafloor spreading at the south of your "Africa" but I can't see any compensatory subduction.

Otherwise, I think there should be transform faults at the north pole but the 3D-shown-as-2D map is messing my map-reading up.

Well, I've taken my sweet time on getting this up, but here's a modified version of my tectonics map! Now with transform boundaries and tectonic activity at the southern plate!

Well, your edge ocean will be swallowed fast, I think. Not sure how plausible that is. A continent has a lot of base friction and if an oceanic plate was encased by two continents with subduction zones it's likely that the trench pull would open up a ridge in the ocean. I am not sure on that, though.