 The Fichtel mountains are also characterized by large granite bodies, called post-kinematic plutons which, in the late phase of Variscan orogeny, intruded into the metamorphic rocks.In most cases these are S-type granites whose melting was caused by heated-up sedimentary rocks sunk deep into the Earth's crust.While the Fichtel and Franconian Forest can be assigned to the Saxo-Thuringian Zone of Central European Variscan orogeny, the Spessart belongs to the Central German Crystalline Zone.