My New Terra ...

[Pixie]

Naima, that's way too many ridge shaped young mountain ranges inland for tectonics to explain... can you do localized erotion in FT or Wilbur and bring them down a great deal?

Also, I never got round to explain to you what I meant by assymmetrical oceanic crust... here's a drawing explaining my point in one of your seas - actually, it's the major "implausibility" I find in your map.


The way I see it, the best solution is to have both rifts still active, as they do not coincide exactly... it would need a little of messing about with direction of boundaries and land shapes in that area. That is, of course, if you want to be bothered about this scientific accuracy thing.

[Naima]

Thankyou ,For the Continent showed in the pic ( the africa like one ) yes the ridges are a test , I wanted to exagerate to see them in the projection and to be sure that the "big" rivers get in the right direction , I can erode them more after ...
I wanted to also have "old ridges" on the rest of the continent and two main ones , one from the forming rift and one from the northerneast border .... would that work?

As for the picture u posted ( I call those Americalike continents for the moment lol ) you sugest to make a "failed" rift in the water and leave the tectonics as they are or to shift the rift west more or have a secondary plate in between?

[Pixie]

... having the two active dorsals, that's what I suggest. The one on the eastern basin needs to be moved slightly westwards to be centered and the other one should be more or less where I have the orange dotted line. This would add a subduction zone where those islands are.

If you choose this way, those east-west oriented peninsulas have no plausible origin and the coasts should mirror the direction of the rift(s) quite closely - it's a young ocean after all.
If you choose to have just the one original dorsal, then a lot of that sea with the peninsulas is submerged old crust and there should be mountains (not too tall, maybe turned into a line of islands oriented north-south, originating when that was a continental rift) along the line between the continental and the new oceanic crust on the western plate, but you can have a large sea bed behind it - a shallow sea, filling up with sediment which means lowlands at the coast as well.

[Naima]

mmm at this moment its easier to me to change the oceanic dorsal rather than the mountain ridges, I can easily sink and rise peninsulas and islands but a whole ridge might be problematic ... how if I shift the ocean ridge?

[Pixie]

If it is just one ocean ridge is easier. It just needs to be more or less equidistant to both continent margins, and they need to fit reasonably well. No peninsulas, but some small to very small volcanic islands are ok. In that case this would be like the Atlantic over 100 million years ago or the Red Sea another 50 million years into the future.

[Naima]

Should the small islands be on coasts siding the rift or on the rift itself?

Also what if I add a secondary plate in between having so a double rift one passing for the break inthe land on right continent and another among the islands?

I kind of liked the idea of the islands in between the two continents, the idea was that it was once a big continent that started to sink in the middle and ripped apart n two directions leaving pieces of land here and there in between .

[waldronate]

Unit2 shows a cross section of the Atlantic between America and Europe. Note how the ocean depths drop off away from the rift itself. If the ocean is pretty shallow (that is, not very wide), then you might get something like Iceland (the rift breaks the surface there).

Oregon: A Geologic History - The Big Picture: Plate Tectonics and Hot Spots is a good generalized diagram for the types of zones that you might get. A good back-arc basin and island chain like Japan might work for you, as might a set of hot-spot islands like Hawaii.

[Pixie]

A secondary plate, which means two oceanic dorsals, slightly oblique, is the solution I suggested.

I kind of liked the idea of the islands in between the two continents, the idea was that it was once a big continent that started to sink in the middle and ripped apart n two directions leaving pieces of land here and there in between .

The thing with this is that the pieces of land are still attached to each other underwater as the continent is hundreds of km's deep in most cases... they would still move east/west with the rest of the continental crust, not left behind.
If they were left behind, that would mean multiple faults/rifts, and competing spreading zones become a single spreading zone pretty quickly (in geological terms).

[Naima]

Unit2 shows a cross section of the Atlantic between America and Europe. Note how the ocean depths drop off away from the rift itself. If the ocean is pretty shallow (that is, not very wide), then you might get something like Iceland (the rift breaks the surface there).

Oregon: A Geologic History - The Big Picture: Plate Tectonics and Hot Spots is a good generalized diagram for the types of zones that you might get. A good back-arc basin and island chain like Japan might work for you, as might a set of hot-spot islands like Hawaii.

I will take a look thanks .

A secondary plate, which means two oceanic dorsals, slightly oblique, is the solution I suggested.



The thing with this is that the pieces of land are still attached to each other underwater as the continent is hundreds of km's deep in most cases... they would still move east/west with the rest of the continental crust, not left behind.
If they were left behind, that would mean multiple faults/rifts, and competing spreading zones become a single spreading zone pretty quickly (in geological terms).

So I could rise the water between the two continents and simulate a whole single continent with central part sinked but not under the shelf level ? then incise the two different rifts?

[Naima]

Here is reqorked ocean dorsal line between the two amerika continents, I rised the sea on the left replacing islands ... how bout that ? or what further changes there to add?