The Meliaticum of the eastern Alps – sourced from the east, displaced to the west

Ocean floor sediments of the Austroalpine Meliata Basin, as part of the Neo-Tethys, contain a variety of rocks interpreted as tectonic mélange. Laminated siltstone, mudstone, radiolarite, and intercalated sandstone represent the Middle Triassic to Middle Jurassic deep-water deposits that contain shallow marine components derived from a carbonatic–clastic shelf. The U/Pb detrital zircon age data from those sandstones suggest the presence of different sources: (1) An Avalonian source delivered abundant Mesoproterozoic zircons from domains bordering Moesia and East European Platform. (2) A Galatian / Ligerian source, as part of the Armorican / Galatian / Ligerian continent, devoid of Mesoproterozoic zircons but with abundant Mississippian zircons (c. 350 Ma), supplied the Meliata Basin with detritus from the ALCAPA super-terrane. (3) Serbo-Macedonia and/or Dacia delivered detritus devoid of Mesoproterozoic zircons, but prevalent Pennsylvanian zircons (c. 310 Ma). Screening datasets from the Alpine–Carpathian–Balkan orogenic belt for granitoid crystallization ages and detrital zircon spectra enables the identification of the ‘home’ of the Austroalpine Meliaticum. The original site of deposition was a seaway extending at a high angle to the Neo-Tethys margin northwards between ALCAPA/Tisza and Dacia, connecting the Neo-Tethys Ocean with the evolving Piemont-Ligurian Ocean. During the Late Jurassic, when the Piemont-Ligurian Ocean (Alpine Tethys) widened and the Neo-Tethys closed, the Austroalpine Meliata units were displaced approximately 400 km westward along a transform fault system connecting both oceans and penetrating the thinned ALCAPA crust.