On the tectonics of the eastern Betic Cordilleras (SE Spain)

Abstract

The tectonically deepest part of the eastern Betic Cordilleras consists of rocks showing medium grade metamorphism of alpine age. In this zone several individual tectonic units are distinguished, each with a basis of polymetamorphic pre-Silurian schists, covered by a sequence of younger metamorphites considered to be partly of Triassic age. The “crystalline schists of the Sierra Nevada“, together with their cover of younger schists — which represent the deepest part of the “mixed zone“ of previous authors — form a single tectonic unit. It seems appropriate to combine the “crystalline schists of the Sierra Nevada“ and this former “mixed zone“ to a complex of tectonic units, which are characterized by a medium grade metamorphism of alpine age and for which the name Nevado-Filabride units or Nevado-Filabrides is proposed. The Nevado-Filabrides are tectonically overlain by the Alpujarrides, generally characterized by low grade alpine metamorphism, and these in their turn by the Betic of Malaga — merely present as small dispersed remnants — consisting of rocks that are almost devoid of alpine metamorphism. Important movements, that have taken place after the major thrust movements leading to the formation of the nappe structures, have caused horizontal displacements of considerable magnitude, sometimes resulting in changes of the original tectonic succession.