Geodynamic development of the NCA.

Research project P 13688 Geodynamic development of the NCA Hermann J. MAURITSCH 28.06.1999 In an integrated approach using paleomagnetism and surface structural geology, we propose to obtain a comprehensive data base concerning the overall motions of the Northern Calcareous Alps (NCA) and its major structural units. The data we plan to collect will provide a quantitative (regarding space and time) frame work to aid paleogeographic modelling. We chose the NCA as a key representative of the entire Austroalpine unit, because they show long stratigraphic successions and are mostly unmetamorphosed (except for the southernmost part). Although several paleornagnetic studies on the NCA have already been published, most of them were conducted using equipment that does not meet modem standards, and, thus, those of the results that pass modem reliability criteria are limited to a few strongly magnetized stratigraphic horizons. However, the kind of equipment that is available today will enable us to also obtain reliable results from other strata. In a pilot study on weakly magnetized upper Santonian to lower Eocene Gosau deposits from the Neue Welt area in the eastern NCA, we demonstrate the feasibility of modem paleomagnetism to solve problems regarding the structural evolution of this complex orogenic belt. We plan to sample continuous profiles covering long time spans and use these profiles as a frame work for the more specific tasks of this project, such as the motion histories of the major lineaments. We plan to combine our results with the existing paleogeographic models, and expect that we will solve some of the discrepancies between these models, and also answer some of the still debated problems.