In the general discussion on the Variscan evolution of central Europe
the pre-Mesozoic basement of the Alps is, in many cases, only included
with hesitation. Relatively well-preserved from Alpine metamorphism, the
Alpine External massifs can serve as an excellent example of evolution
of the Variscan basement, including the earliest Gondwana-derived
microcontinents with Cadomian relics. Testifying to the evolution at the
Gondwana margin, at least since the Cambrian, such pieces took part in
the birth of the Rheic Ocean. After the separation of Avalonia, the
remaining Gondwana border was continuously transformed through crustal
extension with contemporaneous separation of continental blocks
composing future Pangea, but the opening of Palaeotethys had only a
reduced significance since the Devonian. The Variscan evolution in the
External domain is characterised by an early HP-evolution with
subsequent granulitic decompression melts. During Visean crustal
shortening, the areas of future formation of migmatites and intrusion of
monzodioritic magmas in a general strike-slip regime, were probably in a
lower plate situation, whereas the so called monometamorphic areas may
have been in an upper plate position of the nappe pile. During the
Latest Carboniferous, the emplacement of the youngest granites was
associated with the strike-slip faulting and crustal extension at lower
crustal levels, whereas, at the surface, detrital sediments accumulated
in intramontaneous transtensional basins on a strongly eroded surface.
To cite this article: J.R von Raumer et al., C. R. Geoscience 341
(2009). (C) 2008 Academie des sciences. Published by Elsevier Masson
SAS. All rights reserved.