I would propose to use xenoceans for any ocean out of the Earth. From Xenos = alien. They are different enough in structure and composition to deserve their own name.

Iceans may be confusing, as it does not suggest a liquid stage under the platform, and ice suggests presence of water in something that is not necessarily composed of water, but the second layer of ice created by pressure is something never found before for sure, so it may deserve a chance.

Very cool worlds. Finding an entire alien marine ecosystem would be incredible.