Comment on Dorr and Zulauf: Elevator tectonics and orogenic collapse of a Tibetan-style plateau in the European Variscides: the role of the Bohemian shear zone. Int J Earth Sci (Geol Rundsch) (2010) 99: 299-325

The present comment disproves the tectonic model of a late Devonian/early Carboniferous Tibetan-style collisional plateau in the Tepla-Barrandean (TB) part of the Bohemian Massif, which later collapsed by thermal weakening of the underlying crust. Contrary to this model, the TB neither reveals major crustal thickening nor uplift and erosion, and eastern continuations of the TB were, during the relevant time-span, areas of open marine sedimentation. Late Devonian/early Carboniferous marine sediments widespread also in the Armorican and Central Massifs of France testify to low topography in central parts of the Variscan orogen. Notional traces of a Permo-Carboniferous ice cap on the French Massif Central do not support the plateau model, because they are questionable and much younger than the inferred plateau stage of the TB. The relative uplift of high-grade metamorphic rocks to the NW and the SE of the TB is not due to sinking of an elevated TB, but, instead, to the hydraulic and buoyant expulsion of HP material from the Saxo-Thuringian and Moldanubian subduction channels. The rise of lower-grade HT rocks along the southwestern margin of the Bohemian Massif was effected by late Carboniferous transpression. The high temperature and the resulting low viscosity of the rising materials were probably not caused by Variscan mantle delamination, but relate to lithospheric thinning and heating at the tip of the westward propagating Tethys Rift.