Research

Ongoing reserach of the petrology group at Tübingen University focusses on three major topics: Fluid-rock interaction processes, halogen studies and magmatic petrology and geochemistry, mainly (but not exclusively) of alkaline, peralkaline and carbonatitic rocks. Obviously, all topics may be linked to each other, depending on the specific research project.

New EU-funded research project on alkaline rocks and carbonatites

The petrology Group is part of a new collaborative research project on alkaline rocks and carbonatites called HiTech AlkCarb.

The project has received € 5.4 Million funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 689909 and begins february 2016.

The project brings together industry partners involved in exploration, geophysics and environmental asessment in a team with geological surveys and university academics. This project will make a step-change in exploration models for alkaline and carbonatite provinces, establishing methodologies by which mineralogy, petrology, geochemistry and geophysics, including state-of-the-art interpretation of high resolution geophysics and downhole measurement tools, can be used to make robust predictions about mineral prospectivity at depth. This will be achieved through studies at seven key natural laboratories (Germany, Italy, Greenland, Malawi, Mongolia, Namibia, South Africa). The outcomes will be incorporated into new geomodels on mutiple scales from a world catalogue to deposit models.

Project leader: University of Exeter (GB)

Partners: University Tübingen (Germany), University of St Andrews (Scotland), G.d'Annuzio University (Italy), Mendel University (Czech Republic), Natural History Museum London (GB), GeoAfrica (Portugal), Terratec Geophysical Services (Germany), Lancaster Exploration Ltd (GB), A. Speiser Environmental Consultants (Portugal), British Geological Survey (BGS), Geological Survey of Denmark and Greenland (GEUS).

HiTech AlkCarb Homepage: http://carbonatites.eu

Fluid-rock interaction processes

At the moment, quite a number of undergraduate and graduate students work on the mineralogy, petrology and geochemistry of hydrothermal ore deposits, mainly located in SW Germany (Schwarzwald). Detailed questions concern the nature of the fluids involved in their genesis, the source of the metals and other elements (e. g., F, S, C) present in the deposits, the role of fluid mixing during mineralization and the details of element redistribution during weathering. Methods involved are detailed transmitted and reflected light microscopy, followed by fluid inclusions studies, stable and radiogenic isotope analyses, microprobe investigations and micro-XRD studies.

Related to these studies, surface and mineral waters in SW Germany are investigated with respect to their REE concentrations, and compared to the REE composition of young, secondary minerals (sinter calcite, gibbsite, Fe and Mn oxyhydroxides, REE minerals) precipitated from these waters. The REE are used here as monitor of fluid-vein reactions. It is planned to perform similar studies with uranium.

Halogens in Earth’s materials

Halogens (F, Cl, Br, I) are important, partly common and interesting elements in a large variety of geological processes and their geochemical and petrological behavious allows to understand processes like metasomatism, subduction, hydrothermal vein formation or magmatic degassing in great detail. As Iodine is the rarest of these elements (and therefore, most difficult to analyze, because of its very low abundances in most materials), and Cl as well as F are relatively abundant, we have specialized in the detection and quantification of Br. Cl-F-Br-analyses applied to both hydrothermal veins and magmatic and metamorphic rocks will be a major topic in the coming years in Tübingen. Methods used are electron microprobe, TXRF (the first instrument in German Geosciences), pyrohydrolysis and ion chromatography. Halogen studies form a bridge between the other investigations performed in our group.

Magmatic petrology and geochemistry

In the last decade, Tübingen petrology mainly focussed on the petrology and geochemistry of alkaline and peralkaline magmatic rocks such as nepheline syenites or carbonatites. This research led to a wealth of publications. Studies on the origin of magmatic layering, of degassing phenomena during fractional crystallization or of rare element enrichment processes during differentiation of melts and during hydrothermal alteration of magmatic bodies are current and future research topics. Methods involved are stable and radiogenic isotope analytics, whole-rock XRF, electron microprobe as well as computer-based modelling of crystallization or reaction processes.