Jurassic mountain building and Mesozoic-Cenozoic geodynamic evolution of the Northern Calcareous Alps as proven in the Berchtesgaden Alps (Germany) |
| |
Authors: | Sigrid Missoni Hans-Jürgen Gawlick |
| |
Institution: | (1) Department for Applied Geosciences and Geophysics: Prospection and Applied Sedimentology, University of Leoben, Peter-Tunner-Str. 5, 8700 Leoben, Austria |
| |
Abstract: | New data from the Berchtesgaden Alps result in a reconstruction of the Mesozoic-Cenozoic geodynamic history of the Northern
Calcareous Alps. The closure of the western part of the Neotethys Ocean started in the late Early Jurassic and is evidenced
by the onset of thick clay-rich sediments in the outer shelf area (=Hallstatt realm). The Middle to early Late Jurassic contraction
is documented by the migration of trench-like basins formed in front of a propagating thrust belt. Due to ophiolite obduction,
these basins propagated from the outer shelf area, forming there the Bajocian to Oxfordian Hallstatt Mélange, to the Hauptdolomit/Dachstein
platform area, where the Oxfordian Rofan and Tauglboden Mélanges were formed. The basins were separated by nappe fronts forming
structural highs. This scenario mirrors syn-orogenic erosion and deposition in an evolving thrust belt. Active basin formation
and nappe thrusting ended around the Oxfordian/Kimmeridgian boundary, which was followed by the onset of carbonate platforms
on structural highs prograding towards the former basins in latest Oxfordian to Early Tithonian time. Underfilled basins remained
between the platforms. Rapid deepening around the Early/Late Tithonian boundary was induced by extension due to mountain uplift
and resulted in the reconfiguration of the platforms and basins related to normal and probably strike-slip faults. Erosion
of the uplifted nappe stack including obducted ophiolites caused final drowning and demise of the platforms in the Berriasian.
The remaining Early Cretaceous basins were filled up with molasse sediments including siliciclastics until Aptian. Around
the Early/Late Cretaceous boundary again extension and strike-slip movements started, followed by Eocene thrusting and Miocene
strike-slip movements with block rotations. These younger tectonic movements destroyed the Triassic to Early Cretaceous palaeogeography
and arranged the modern block configuration. The described Jurassic to Early Cretaceous history corresponds with that of the
Western Carpathians, the Dinarides, and the Albanides, where (1) age dating of the metamorphic soles prove late Early to Middle
Jurassic inneroceanic thrusting followed by late Middle to early Late Jurassic ophiolite obduction, (2) Kimmeridgian to Tithonian
shallow-water platforms formed on top of the obducted ophiolites, and (3) latest Jurassic to Early Cretaceous sediments show
postorogenic character. Therefore, we correlate the Jurassic geodynamic evolution of the Northern Calcareous Alps with the
closure of the western part of the Neotethys Ocean. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|