For many raw material relevant questions it is necessary to gain knowledge about the geometry (e.g. location and depth extension of the deposit) and the petrophysical properties of deposits. However, such information can only be derived to a limited extent directly from the measured geomagnetic field. Here, spatial (3D) modeling of the distribution of magnetic susceptibility, or magnetization, of the subsurface can provide essential information. However, especially due to the very complex metallogenesis of the Eastern Alps, such modeling is difficult without additional knowledge about structure and tectonics. Under certain circumstances, modeling of unmineralized magnetic marker horizons can also contribute to the resolution of the structure of a mineralization.

The metallogenesis of the Eastern Alps is multiphase and very complex. On the one hand there are syngenetic stratabound mineralizations (often hydrothermally overprinted) and on the other hand there are epigenetic hydrothermal mineralizations which are mostly closely linked to alpine tectonics and metamorphism. In hydrothermal systems related to mineral deposits, fluids in shear and fault zones play a central role. Since alpine tectonics and metamorphism are controlling factors for the tectonic position, formation and shape of mineralizations as they appear today, the resolution of the geological structure is essential for an understanding of metallogenesis. In the Bohemian Massif mineralization is often related to hydrothermal alteration in the course of magmatic activity (greisen and skarn deposits).

In many metallogenetic units of Austria magnetite and pyrrhotite occur in different amounts. The extremely high magnetic susceptibility of magnetite means that even rocks with low contents can cause noticeable geomagnetic anomalies. Magnetite-bearing rocks and mineralizations can thus be easily detected. To a lesser extent, the same is true for pyrrhotite. Magnetite bearing rock types are mainly intermediate and basic (meta-)vulcanites and (meta-)plutonites. Ultrabasites, which show only moderate magnetization as fresh rocks, become extremely high magnetic with increasing alteration and metamorphism due to progressive serpentinization and associated increasing magnetite content.

In the first phase of the project the possibilities of the software packages "Mag3D" and "Oasis Montaj (Geosoft)" will be explored. "Mag3D" is software for automatic 3D inversion of geomagnetic data. It models magnetic susceptibility without considering remanent magnetization. "Oasis Montaj" allows the creation and display of 3D models as well as the inversion of both magnetic susceptibility and magnetization vector in magnitude and direction (induced and remanent magnetization). This software is widely used in the exploration and mining industry. Tests for software development respectively to get familiar with the software packages will be performed on real measured data.

In the second phase of the proposed project, the previously identified solution methods for creating 3D models from geomagnetic data will be applied to additional test areas. The selection of the test areas, the processing of the geological and petrophysical information as well as the interpretation of the results shall be done in close cooperation with the Department of Mineral Resources of the GBA. If necessary, in-situ magnetic susceptibility measurements will be carried out on geological outcrops in connection with this 3D modeling.

» Final report; approved by the BMF: 05.06.2023
» Interim report 2021; approved by the BMLRT: 22.02.2022
» Interim report 2020; approved by the BMLRT:: 10.03.2021
» Interim report 2018/2019; approved by the BMLRT: 25.05.2020
» Interim report 2017/2018; approved by the BMNT: 11.02.2019