Formation of a Composite Albian–Eocene Orogenic Wedge in the Inner Western Carpathians: P–T Estimates and 40Ar/39Ar Geochronology from Structural Units

The composite Albian–Eocene orogenic wedge of the northern part Inner Western Carpathians (IWC) comprises European Variscan basement with Upper Carboniferous–Triassic cover and Jurassic to Cretaceous sedimentary successions a large oceanic–continental Atlantic (Alpine) Tethys basin system. This paper presents an updated evolutionary model for principal structural units (i.e., Fatricum, Tatricum Infratatricum) based on new published white mica 40Ar/39Ar geochronology P–T estimates by Perple_X modeling geothermobarometry. north-directed collision led closure Jurassic–Early basins, incorporation their infill thinned into Albian–Cenomanian/Turonian accretionary wedge. During this compressional D1 stage, subautochthonous Fatric units, including present-day higher Infratatric nappes, achieved metamorphic conditions ca. 250–400 °C 400–700 MPa. collapse contemporary southward Penninic oceanic subduction enhanced extensional exhumation low-grade metamorphosed complexes (D2 stage) opening fore-arc basin. hemipelagic Coniacian–Campanian Couches-Rouges type marls (C.R.) spread from Tatric edge, throughout Belice Basin, up peri-Pieniny Klippen Belt Kysuca thus tracing south-Penninic subduction. ceasing switched regime recorded in trench-like “flysch” trough formation lower anchi-metamorphism C.R. at 75–65 Ma (D3 stage). was followed thrusting exhumed anchi-metamorphosed over frontal unmetamorphosed lowest Campanian–Maastrichtian sediments 65–50 (D4 Phengite marble sample SRB-1 meta-marl HC-12 produced apparent step ages clustered around 90 Ma. A mixture interpretation age is consistent presence older Ph1 related burial (D1) within On contrary, younger Ph2 closely late- post-Campanian (D3) thrust fault Celadonite-enriched muscovite Zobor Nappe meta-quartzite ZI-3 yielded mini-plateau 62.21 ± 0.31 which coincides closing foreland trough, accretion Infratatricum Tatricum, rear Fatricum bivergent structure Eocene