A Late Tournaisian synmetamorphic folding and thrusting event in the eastern Variscan foreland: 40Ar/39Ar evidence from the phyllites of the Wolsztyn–Leszno High, western Poland

Abstract

A Late Tournaisian synmetamorphic folding and thrusting event in the eastern Variscan foreland: 40 Ar/ 39 Ar evidence from the phyllites of the Wolsztyn-Leszno High, western Poland Abstract A Variscan foreland in western Poland comprises two NW-trending basement highs, which are concealed under Carboniferous through Triassic strata of the Fore-Sudetic Monocline (FSM). Both highs consist of multiply deformed quartz-sericite € albite € chlorite phyllites of unknown protolith age. 40 Ar/ 39 Ar laser probe dating of white micas in up to 0.5-mm-thick mica layers, which form the S 2 axial-plane foliation in phyllites of the Wolsztyn-Leszno High, yielded an age of 340.1€2.6 Ma for the lower greenschists facies metamorphism and probably also for the F 2 folding. This deformation was associated and followed by thrusting, which brought about the basement highs. The latter delivered clasts to overlying late VisØan-early Namurian flysch basin that was mainly sourced from the Saxothuringian Sudetes in which most of the deformation occurred between 345-335 Ma. The FSM basement may represent an independent terrane, referred to as the Wielkopolska terrane, belonging to the Armorican Terrane Assemblage.

Lithospheric structure of the Bohemian Massif and adjacent Variscan belt in central Europe based on profile S01 from the SUDETES 2003 experiment

“…The TESZ that corresponds to the southern margin of the Old Red Continent appears to be overridden from the south by the Variscan orogenic wedge reaching as far north beneath the Fore‐Sudetic Monocline as the Dolsk fault (Figures 2 and 11). The high‐velocity lower crust and upper mantle of the TESZ domain extend to the south up to the Odra fault zone and can be interpreted as the attenuated Baltica margin [ Grad et al , 2002a] or the edge of any other terrane potentially incorporated into the TESZ (e.g., magmatically underplated Avalonian lower crust [ Mazur and Jarosiński , 2006], the Wielkopolska terrane of Żelaźniewicz et al [2003], of the Kuiavia and/or Pomerania terranes of Dadlez et al [2005]. Leaving the particularities of detailed terrane models still open, we interpret the upper crust of the Fore‐Sudetic Monocline between the Odra and Dolsk fault zones (Figures 2, 6, 9, and 11) as part of a Variscan retrowedge back thrust toward the north onto the plate margin marked by the TESZ.…”

Crustal lithology vs. thermal state and Moho heat flow across the NE part of the European Variscan orogen: a case study from SW Poland

“…The Permo-Mesozoic sedimentary rocks overlay Carboniferous turbiditic succession of the thickness exceeding 2500 m, reduced in the areas of Bielawy-Trzebnica and Wolsztyn-Leszno Horsts, formed by Paleozoic phyllites metamorphosed at 340 Ma (Żelaźniewicz et al 2003;Mazur et al 2010a). Phyllites are the oldest lithology drilled in the basement of the Fore-Sudetic Monocline and are unconformably overlain by turbidites.…”

Geomorphological and Neotectonic Structures Studied in the Southern Part of the Moesian Platform in Romania

“…the Danube River is the Danube platform (comprising vast Quaternary structural lowlands and Pliocene platforms), also known as the Danubian hilly plain [9]. When addressing the Moesian Platform's geotectonic history, contrasting concepts have been carried out [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] due to scarce geological data on the basement, while the geophysical data did not clarify the structural relationships between the Moesian terranes.…”

“…4 km depth) and depressionary areas (such as the Alexandria Depression-more than 10 km depth, Focşani Depression-more than 16 km depth, Getic Depression-more than 14 km depth). Four main sedimentary cycles have been separated based on borehole geological and geophysical data analysis and When addressing the Moesian Platform's geotectonic history, contrasting concepts have been carried out [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] due to scarce geological data on the basement, while the geophysical data did not clarify the structural relationships between the Moesian terranes.…”