The Variscides of Poland and northern Czechia comprise metamorphic internides that crop out in the Sudetes at the NE margin of the Bohemian Massif and an external fold-and-thrust belt, which is buried beneath a thick Permian-Mesozoic succession of the German-Polish basin in central-western Poland. A foreland basin flanks the Variscan external belt in the N and NE, locally reaching up to, or even onlapping the Teisseyre-Tornquist Zone. The Sudetes represent a mosaic of geologically distinct, fault-bounded pre-Permian units affected by Devonian to Carboniferous deformation and metamorphism that are characterized by radical changes in the dominant structural trends. These units are partly overlain by syn- to post-orogenic Variscan and post-Variscan basins, having sedimentary and—less abundant—volcanic fill of age varying between late early Carboniferous to mid-Triassic and Late Cretaceous to Cenozoic. The Sudetic Variscan terranes seem to continue into those known from the Bohemian Massif, Germany, France, and Spain, which are generally believed to represent the Armorican Terrane Assemblage or directly the West African margin of Gondwana. The exception makes the East Sudetes that comprise crystalline units derived from the Brunovistulian terrane, showing affinities to Amazonia or Baltica. The Sudetes developed, along with the entire Variscan belt, during Devonian and Carboniferous times in response to closure of at least two marine basins floored by oceanic crust, concomitant amalgamation of the peri-Gondwana terranes, and their subsequent accretion to the SW margin of Laurussia in the process of making up of Pangea. Despite the structural complexity, a general WNW-ESE tectonic polarity can be observed in the Sudetes that can be explained in terms of a two-plate system with the lower, Saxothuringian plate in the west, the frontal and rear accretionary wedges in the middle and the upper, Brunovistulian plate in the east. This simple scheme is, however, complicated by diachroneity in the evolution of particular system components, controlled by at least two stages of convergence—in Early Devonian and early Carboniferous times, and strike-slip displacements on the major, Intra-Sudetic fault zone, splitting the Sudetes into halves. The SSW half was heavily affected by collisional processes in the early Carboniferous, whereas the NNE one preserved vestiges of an original accretionary structure from Devonian times. The Sudetes include Neoproterozoic terranes affected by Cadomian convergence that lasted until at least the early Cambrian, and by subsequent, late Cambrian, mostly felsic plutonism, related to an uncertain, but presumably post-orogenic setting. The first indications of continental rifting at the northern margin of Gondwana date back to the earliest Ordovician. The beginning of orogenic convergence in the Sudetes was recorded in the Early Devonian, synchronously with opening of a short-lived back-arc oceanic basin that gave birth to the Central Sudetic ophiolite. The subsequent early Carboniferous tectonism peaked at c. 340 Ma and was associated with closure of all oceanic domains between Gondwana and Laurussia, continental subduction and final emplacement of metamorphic nappes. This event was followed by general uplift, folding episodes due to differential motions between the component tectonic elements and late- to post-orogenic magmatism that continued until the beginning of Permian.

The Geology of Variscan Sudetes and Their Northern Foreland

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发表日期：

2025年

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Stanisław Mazur,
Paweł Aleksandrowski,
Łukasz Gągała

摘要

The Variscides of Poland and northern Czechia comprise metamorphic internides that crop out in the Sudetes at the NE margin of the Bohemian Massif and an external fold-and-thrust belt, which is buried beneath a thick Permian-Mesozoic succession of the German-Polish basin in central-western Poland. A foreland basin flanks the Variscan external belt in the N and NE, locally reaching up to, or even onlapping the Teisseyre-Tornquist Zone. The Sudetes represent a mosaic of geologically distinct, fault-bounded pre-Permian units affected by Devonian to Carboniferous deformation and metamorphism that are characterized by radical changes in the dominant structural trends. These units are partly overlain by syn- to post-orogenic Variscan and post-Variscan basins, having sedimentary and—less abundant—volcanic fill of age varying between late early Carboniferous to mid-Triassic and Late Cretaceous to Cenozoic. The Sudetic Variscan terranes seem to continue into those known from the Bohemian Massif, Germany, France, and Spain, which are generally believed to represent the Armorican Terrane Assemblage or directly the West African margin of Gondwana. The exception makes the East Sudetes that comprise crystalline units derived from the Brunovistulian terrane, showing affinities to Amazonia or Baltica. The Sudetes developed, along with the entire Variscan belt, during Devonian and Carboniferous times in response to closure of at least two marine basins floored by oceanic crust, concomitant amalgamation of the peri-Gondwana terranes, and their subsequent accretion to the SW margin of Laurussia in the process of making up of Pangea. Despite the structural complexity, a general WNW-ESE tectonic polarity can be observed in the Sudetes that can be explained in terms of a two-plate system with the lower, Saxothuringian plate in the west, the frontal and rear accretionary wedges in the middle and the upper, Brunovistulian plate in the east. This simple scheme is, however, complicated by diachroneity in the evolution of particular system components, controlled by at least two stages of convergence—in Early Devonian and early Carboniferous times, and strike-slip displacements on the major, Intra-Sudetic fault zone, splitting the Sudetes into halves. The SSW half was heavily affected by collisional processes in the early Carboniferous, whereas the NNE one preserved vestiges of an original accretionary structure from Devonian times. The Sudetes include Neoproterozoic terranes affected by Cadomian convergence that lasted until at least the early Cambrian, and by subsequent, late Cambrian, mostly felsic plutonism, related to an uncertain, but presumably post-orogenic setting. The first indications of continental rifting at the northern margin of Gondwana date back to the earliest Ordovician. The beginning of orogenic convergence in the Sudetes was recorded in the Early Devonian, synchronously with opening of a short-lived back-arc oceanic basin that gave birth to the Central Sudetic ophiolite. The subsequent early Carboniferous tectonism peaked at c. 340 Ma and was associated with closure of all oceanic domains between Gondwana and Laurussia, continental subduction and final emplacement of metamorphic nappes. This event was followed by general uplift, folding episodes due to differential motions between the component tectonic elements and late- to post-orogenic magmatism that continued until the beginning of Permian.