Pre-Mesozoic Alpine basements—Their place in the European Paleozoic framework

Abstract

Prior to their Alpine overprinting, most of the pre-Mesozoic basement areas in Alpine orogenic structures shared a complex evolution, starting with Neoproterozoic sediments that are thought to have received detrital input from both West and East Gondwanan cratonic sources. A subsequent Neoproterozoic-Cambrian active margin setting at the Gondwana margin was followed by a Cambrian-Ordovician rifting period, including an Ordovician cordillera-like active margin setting. During the Late Ordovician and Silurian periods, the future Alpine domains recorded crustal extension along the Gondwana margin, announcing the future opening of the Paleotethys oceanic domain. Most areas then underwent Variscan orogenic events, including continental subduction and collisions with Avalonian-type basement areas along Laurussia and the juxtaposition and the duplication of terrane assemblages during strike slip, accompanied by contemporaneous crustal shortening and the subduction of Paleotethys under Laurussia. Thereafter, the fi nal Pangea assemblage underwent Triassic and Jurassic extension, followed by Tertiary shortening, and leading to the buildup of the Alpine mountain chain. Recent plate-tectonic reconstructions place the Alpine domains in their supposed initial Cambrian-Ordovician positions in the eastern part of the Gondwana margin, where a stronger interference with the Chinese blocks is proposed, at least from the Ordo vician onward. For the Visean time of the Variscan continental collision, the distinction of the former tectonic lower-plate situation is traceable but becomes blurred through the subsequent oblique subduction of Paleo tethys under Laurussia accompanied by large-scale strike slip. Since the Pennsylvanian, this global collisional scenario has been replaced by subsequent and ongoing shortening and strike slip under rising geothermal conditions, and all of this occurred before all these puzzle elements underwent the complex Alpine reorganization.

Thick-Skinned and Thin-Skinned Tectonics: A Global Perspective

“…In Devonian and Early Carboniferous times the ribbon continents were amalgamated and in Late Carboniferous times Laurentia-Baltica and Gondwana collided [158]. Ribbon continent amalgamation and continent-continent collision were accompanied by magmatic activity.…”

“…The Variscan chain running across Europe and connecting to the Appalachians developed from a complex palaeogeographic pattern characterized by two oceans located between Laurentia-Baltica and Gondwana: the Rhenohercynian ocean (a remnant of the Rheic ocean) in the north, and Palaeothethys in the south [167,158]. The Rheic Ocean opened in the Early Ordovician, Palaeotethys in the Devonian.…”

“…The Rheic Ocean opened in the Early Ordovician, Palaeotethys in the Devonian. Microcontinents, or ribbon continents, formed in the intraoceanic area between these two basins [158]. In the traverse of the central European Variscan chain considered here, they include the Saxothuringian, Barrandian and Moldanubian zones [159].…”

Thick-Skinned and Thin-Skinned Tectonics: A Global Perspective

“…The Rheic Ocean opened in the Early Ordovician, Palaeotethys in the Devonian. Microcontinents, or ribbon continents, formed in the intraoceanic area between these two basins [167] [168].…”

The Kellerjoch Gneiss (Tyrol, Eastern Alps): An Ordovician pluton with A-type affinity in the crystalline basement nappes north of the Tauern Window

“…10), the KG is fairly special among these rocks. The Ordovician period is commonly considered as the time when large parts of future Variscan Europe rifted off from the Gondwana margin (Von Raumer et al 2013;see also Blatt 2013). However, S-type and I-type granite magmatism is predominant in that time span, and A-type granites are not particularly abundant, although these would be actually typical for rift settings (Bonin 2007).…”