The Pfitsch-Mörchner Basin, an example of the post-Variscan sedimentary evolution in the Tauern Window (Eastern Alps)

Abstract

A review of post-Variscan metasedimentary and metavolcanic successions in the western Tauern Window is presented. U/Pb – datations of zircons in metavolcanic rocks reveal ages between 309 and 280 Ma. Deposition of grey conglomerates and black pelites started before 309 Ma in the northernmost basin of the Tauern, the Riffler-Schönach basin. In the more central Pfitsch-Mörchner basin, the onset of conglomerate sedimentation can be dated into the time span between 293 and 280 Ma. The Pfitsch and Windtal Formations are newly defined. The basins were filled with up to 1 km of mainly continental clastics until Early Triassic. Short marine ingressions in Middle- and Late Triassic times flooded only basinal parts of the area where we suppose a more or less continuous sedimentation until the Late Jurassic. Only the Hochstegen Marble documents a nearly complete submergence in the area of the Tauern Window. In spite of the metamorphic overprint, the tentative interpretations of the sedimentary facies give a reasonable picture and allow correlations to nonmetamorphic areas in South Germany or the External Massifs of Eastern Switzerland.