Mesozoic paleogeography of the Northern Calcareous Alps—Evidence from paleomagnetism and facies analysis

Abstract

The Northern Calcareous Alps are generally thought to have been part of the same southern Tethyan continental margin as the southern Alps during Late Jurassic and Early Cretaceous time. Contrasting Liassic paleomagnetic data from the Northern Calcareous Alps and the southern Alps can be explained by large-scale clockwise rotation during Late Cretaceous and Tertiary tectonic emplacement of the Northern Calcareous Alps onto the European continental margin. Alternatively, the data can be reconciled by postulating that the Northern Calcareous Alps did not undergo the African Mesozoic rotational history seen in the southern Alps and were separated from the southern Alps by a short-lived branch of Jurassic ocean. Facies analysis in the Karwendel-Thiersee syncline of the Northern Calcareous Alps indicates that the Jurassic basin sediments in this area were deposited in an east-west-oriented sinistral strike-slip fault system. In the southern Alps and central Austroalpine complex, coeval basin sedimentation was controlled by north-south-oriented normal faults. This contrasting basin evolution and evidence for a source of ophiolitic detritus south of the Northern Calcareous Alps argue for a short-lived ocean basin south of the Northern Calcareous Alps that was closed by Early Cretaceous time.