9
$\begingroup$

It is well known that oceanic plates subduct under continental plates. This may be attributed to the plate's age and density, plus the water on top of it.
So I was wondering if it is ever possible for a continental plate to subduct under an oceanic plate, perhaps if the oceanic plate is covered with shallow water? I've tried to search up on this question on many search engines and sites but to no avail. Thanks for your answer!

$\endgroup$
  • $\begingroup$ Water weight doesn't matter than much for subduction. The main effect is indirect by alteration of dense rocks like mantle rocks to less dense rocks such as serpentinites. In that case you can have mantle rocks being "obducted" as ophiolites. $\endgroup$ – Gimelist Nov 9 '18 at 8:32
  • $\begingroup$ But water can play a role in the pressure that has some effect on which plate subducts. Somebody answer plz! $\endgroup$ – Max0815 Nov 11 '18 at 19:20
  • $\begingroup$ Yes, but if you're considering that addition of water to an oceanic plate makes it less dense by average, once you start subducting the continental plate then it becomes submerged as well, and by average loses density. Maybe ophiolites can be the thing you're looking for? It's the reverse, oceanic plates being "obducted" upwards. Also check the concept of delamination, which is the sinking of lower continental plates into the mantle. $\endgroup$ – Gimelist Nov 12 '18 at 11:41
  • $\begingroup$ No. I don't think its what I am actually looking for. So, hmm I think I can explain it in a different way, lets take a simple continental oceanic subduction zone as a scenario. So, now, lets "pause" time, and turn the continental plate into oceanic, vice versa. Will the subduction continue? $\endgroup$ – Max0815 Nov 12 '18 at 21:06
  • 1
    $\begingroup$ This question makes me think of Europa. $\endgroup$ – Muze the good Troll. Mar 13 at 18:50
4
$\begingroup$

No it is not possible because the continental crust's density is lower. Conversely, oceanic plates can subduce under continental ones because they are heavier. This is because continental crusts are formed by granites and sedimentary materials. Their density rounds $2,7g/cm^3$, granites ones, while oceanic crust rounds $3g/cm^3$, basalts and gabbros ones. Oceanic plates start to subduce at a certain age. Presently there are not pre-Jurassic oceanic plates that do it. This is related with the stack of hidrated sediments over the igneous materials.

An exception to this are ophiolites, where oceanic plate obduce continental one. This is not happening presently at any place on Earth, but there are fossilized examples as Semail Ophiolite at Oman.

$\endgroup$
  • 1
    $\begingroup$ That you very much. I waited a LONG LONG time lol :) +1. BTW I think there is a typo in the first sentence. I'll fix. $\endgroup$ – Max0815 Mar 18 at 17:13
  • 1
    $\begingroup$ You are welcome. I made a review of unasnwered questions. My english is poor so if there is any mistake in my speach feel free to edit it. $\endgroup$ – Leukocyte Mar 18 at 17:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.