[Planes] Blackmoor's Elemental Plane of Fire

[Havard]

Is there any mentions to these elemental planes in the official sources?

Yes, the D20 Dave Arneson's Blackmoor Campaign Book is probably the best source. 

But information is scattered a bit here and there. An overview can be found in the section about the Elven Elementalist Prestige Class. 

-Havard