Per Fabrica Ad Astra Wiki

Through the provided configuration for the Custom Ore Generator, each rock layer and ore deposit is placed according to Earth-like patterns. The generation depends on the geological region, or what we call geome, which is derived from the biome.

Geological regions and corresponding biomes
Geome Biome(s)
Continental Anywhere besides oceanic, folded, or volcanic
Oceanic Ocean biomes, and beneath folded mountains
Islands Oceanic above sea-level (not mushroom)
Folded Moutains Ice Mountains, Alps, Highlands, Crag (BoP)
Felsic Volcanic Extreme Hills, Hot Springs (BoP)
Shield Volcano Volcano/Deadlands (BoP)
Granite Dome Glacier (BoP)