[WIP] Map of Forde - from plate tectonics up

[Ottehcnor]

After seeing several threads with a world built from plate tectonics up, I've decided to give it a go. I will be predominantly following this guide, though I am happy to make use of any other resources that others can recommend.

Here are two snapshots from the beginning and end of the Wyneken Era, a period of roughly 200 Million years. (All names are stand-ins at this point, including the name of the world)
image_2000.00Ma.jpg image_1799.00Ma.jpg

These are not intended to be polished maps, but are taken directly from GPlates with no further modification. I may go back to touch up some of these, but really I'm just hoping for feedback on the plate tectonics - if there's anything that particularly stands out as needing revision. (If I do need to include more details to help get feedback, let me know). Right now, I'm trying to figure out what will happen when the island chains in the south west collide - would the islands just be subducted, or would their land mass be agglomerated onto the subducting plate?

[Peter Toth]

Hi Ottehcnor,

Continental crust, including island chains, are never subducted but instead agglomerated onto the overlaying plate. You'll have an Ural-type orogeny, I believe, as the mountains in the island chains are compressed together.

Looking forward to future development on this project, as I always love seeing realistic conworlds!

Peter

[Ottehcnor]

Thanks! Yeah, I had done a little more digging, so I was able to figure that out and move ahead - although you did remind me that I need to include the Ural orogenies, it would have slipped my mind completely!

[Tiluchi]

Would it be possible to post a different view of your second map? I am thinking specifically of a 3D Orthographic view focused on the south pole, as it's currently a little hard to tell which directions your continents are going and how the island arcs are collided. In general I'm sure we'd all be interested to see more of the tectonic history!

In general, two island arcs colliding out in the middle of the ocean as you have here is a rare occurrence, mostly because that means two subduction zones parallel to each other swallowing up a mid-ocean ridge in the process of collision (recall that subduction zones require a mid-ocean ridge "feeding" them crust). This is why it's useful to include oceanic crust and mid-ocean ridges when doing your GPlates simulations, even if it's a major headache. When it does happen it's usually immediately preceding a larger continental collision; if I recall correctly I believe this is what happened with the collision between India and Asia prior to the creation of the Himalaya. Generally speaking, any time an island arc is subducted the former islands are scraped off the subducting plate and accreted onto the overriding plate as a terrane- former island arcs make up most of what is now the Canadian Rockies. So if this were to happen I'm guessing it would create a larger block of continental crust in the ocean, with the subducted island arc forming a terrane and a new volcanic arc forming along the subduction zone. That said I'd have to see a little more of your tectonic history to be sure; I'm not totally sure why there's a subduction zone to the west of your red continent, as it seems like it should be a mid-ocean ridge instead.

[Ottehcnor]

Looking at it now (I've moved ahead about 150 million years since that picture), I'm starting to see four or five points on my map where things just don't make sense, and I think that second map is where I started to go wrong (plus I'm impatient and just wanted to get to continents colliding). For now, I've centered the supercontinent, and can provide the 50 million year increments between the first and second pictures above.
image_2000.00Ma.jpg image_1950.00Ma.jpg image_1900.00Ma.jpg image_1850.00Ma.jpg 1800mya_1800.00Ma.jpg

As well as a 3D ORthographic view from the south (actually about -60 degrees lat.)
image_1800.00Ma.jpg

Part of the issue is simple: I haven't cleaned up the images as well as I should before posting, but more so that I'm still trying to get a handle on the both the software and the theory. I'll do a little work to clean up that last time stop, and post that later. In the meantime, continuing advice is always appreciated.

[Ottehcnor]

Wait, no, the problem really begins in time stop 4, when Red breaks off from Orange - I need to review that, figure out how that break should happen, and then move on from there.

This is so much work, but I can't wait to see the results!

[Ottehcnor]

Back to about 50 my before the second original picture (I need to label stuff better). Here are the two rifts with the direction they will be splitting.

1850 ABCD with arrows.jpg 1850 GHIJ with arrows.jpg

The issue here is with the pink/grey continent, which will start moving towards the mid ocean ridge. So I'm going to have an ocean plate break off and a new subduction zone will open just off the southern coast there. I'm not sure if the islands on the east should break off onto the new plate too, which would lead to them quickly colliding with the continent. Does this move make sense? Do I just need to do it and post what it looks like?

[Ottehcnor]

I think I have a workable map for 2M years from start, a new plate broke off of pink/grey forming a subducted ocean plate, it will likely be completely subducted in the next 50M-100M years, and so a break will form in the ocean crust of green/purple to the south as pink/grey approaches for an eventual collision.

1800 v.2 image_1800.00Ma.jpg

[Ottehcnor]

I still have some work to do on this one, but I wanted to post a brief update to let folks know I'm still working on this. I've had two continent collisions (and about 150 million years) since my last map was posted. Once I do a bit more clean up, I'll re-upload this map with subduction zones and ocean ridges included (and I'll actually label the continents for ease of reference).
image_1650.00Ma.jpg

[Ottehcnor]

It has been a while - but I finished running Forde through plate tectonics. I have roughly 450 million years of geological history. Here is the finished project.

My next step will be climate, but before I get too far into that process, any feedback, suggestions, or questions are welcomed. If you need more information that this map shows to make informed comments, I will do my best to respond with that information as soon as possible, but won't promise any timeline. Life gets busy!

Forde Continents and Mountains.jpg

New mountains are black, older eroded mountains are grey, and I have flipped the poles as well as centering the map at a different point from earlier posts.