Oscar Fernandez , Hugo Ortner, Diethard Sanders, Bernhard Grasemann, Thomas Leitner

One of the most remarkable features of the central Northern Calcareous Alps (Eastern Alps, Austria) is the widespread presence of Upper Triassic deep-water carbonates and Permo-Triassic evaporites resting on deep-water Middle Jurassic sediments and their underlying Upper Triassic shallow-water carbonate platform successions. The Triassic deep-water carbonates and accompanying evaporites have been classically interpreted to originate either from a location south of the time-equivalent carbonate platforms, or to have been deposited in deeper water seaways within the broader platform domain. To date, this dispute has been addressed mostly through the analysis of Triassic and Jurassic facies distribution in map view, which, however, is subject to some degree of ambiguity and subjectivity. In this contribution we present, for the first time, balanced and sequentially restored cross-sections through the central Northern Calcareous Alps to understand the implications of the contrasting paleogeographic models. We present: (a) an interpretation based on a highly allochthonous origin of the Triassic deep-water units; and (b) an interpretation based on their relative autochthony. The restored cross-sections highlight those aspects in each interpretation that need further research. The allochthonous-origin interpretation requires a structural evolution that fails to account for all available constraints. The relative autochthonous-origin interpretation must rest on a concept of deep-water carbonate deposition in intraplatform seaways that satisfactorily accounts for the observed Triassic facies distribution.