I'd like to explore some details on a so-called water-ball planet (i.e. a planet in the habitable zone of a sun, covered by a 100 km deep ocean). I am particularly interested where life could develop on such a planet. I am afraid that it will be a planet full of de-mineralised water where no life form can survive.
Will there be enough salts and other minerals in the ocean for it to be able to host life forms?
What kind of atmosphere do we expect? It could be oxidizing like Earth's atmosphere containing oxygen and nitrogen gas, reducing containing methane, or neutral with almost only water vapor ?
What is on the ground of the ocean? I can think of rock, some kind of ice, or methane hydrate.