Relationship between tectonic structures and generation of anatectic melt, central Spain

Abstract

This study relates the anatectic generation of in situ granites to deformation in the Spanish Central System. Regionally, the principal rocks of the anatectic complexes in central Iberia are migmatites, and interlayered with them are anatectic granites. The second phase of the Hercynian orogeny is characterized by subhorizontal structures (e.g. shears, folding) due to a contractional deformation, followed by extensional collapse of the orogen. Melting and the generation of in situ granites occurred in fertile rocks, but was concentrated in subhorizontal structures formed during the contractional deformation. Accumulation of volatile elements, such as boron, in shear structures may have triggered the anatexis, and enabled local migration of the melt fraction. This process, plus the existence of a fertile source, are determining factors in the generation of different melt-fraction granitoids.