Integrative Ansätze zur Bearbeitung von Magnesitlagerstätten in den Ostalpen

Austria is an important producer of sparry magnesite, which is mainly used in the refractory industry. Even though this raw material has been researched for over 100 years, there are still many unanswered questions about its formation. In the MRI_Magnesit project, modern analytical methods will be used to answer these questions and to revise existing ideas about the magnesite formation.

Austria is an important producer of the raw material magnesite, which is mainly used in the refractory industry and is mined in several sparry magnesite deposits (e.g. near Hochfilzen, Breitenau, Radenthein). Despite its economic importance and intensive research, the formation of sparry magnesite in the Eastern Alps has been the subject of controversial debates for over 100 years (epigenetic-metasomatic vs. syngenetic-sedimentary models).

The chemical composition of fluids in sparry magnesites indicate that waters of high salinity (formed by evaporation of seawater) were involved in the magnesite formation. These data are based on whole rock analyses, whereas fluid inclusion studies on thick sections (microthermometry), which can provide important parameters such as pressure, temperature and salinity, have hardly been carried out to date. The MRI_Magnesite project will now provide these crucial parameters.

In addition to the established isotope measurements (stable C and O isotopes), it is now also possible to measure Mg isotopes and clumped isotopes. First Mg isotope measurements show a clear variation in the analyzed magnesite deposits and further measurements will have to demonstrate to what extent these signatures reflect formation conditions. Clumped isotopes allow the determination of formation temperatures of carbonate minerals for which traditional methods such as microthermometry cannot be applied - a circumstance that applies to most of the sparry magnesites of the Eastern Alps.

In combination with metamorphic temperatures, obtained from measuring the graphitic material associated with sparry magnesites, and trace element analysis (LA-ICP-MS), it will be possible for the first time to fix exact formation conditions of the Eastern Alpine sparry magnesites and to revise the formation model. By linking this with the current state of knowledge on the development of the Eastern Alps, the raw materials industry will also be provided with a significantly expanded basis for further exploration activities.

In order to achieve these goals, the MRI_Magnesit project is investigating key scientific sites of spar magnesite formation: (among others) Kaswassergraben, Diegrub, Hall, Hinterthal-Dienten mining district, Inschlagalpe and Burgsteinpalfen.

In addition to GeoSphere Austria and the Technical University of Leoben, the Graz University of Technology is a scientific co-operation partner. On the industrial side, this project is supported by RHI Magnesita AG.