Where the fountains of the deep are mentioned...Gen 7:12
Gen 8:2 refers to it also.
I see the reference to the fountains of the deep. I think it's a misreading to see this as anything other than a source of the rain.
At any rate, looking for a naturalistic cause or naturalistic evidence of Noak's flood is nonsense. There isn't any. You accept the flood and its subsidence as a miracle or you don't. Looking for evidence makes men into fools and liars.