Usually, mesa biomes cover the entire area without any mixed biomes. But this Minecraft seed offers something very rare.
At coordinates 500, 1300, you will find a savanna oasis amidst a huge mesa biome.
There is also an exposed mineshaft in the area. It has a treasure chest poking from the ground at coordinates 540, 70, 1450. Inside, the chest you will find lots of iron ingots.