Late Variscan high-temperature events in the Saxothuringian and Moldanubian zones of central Europe

• Applicant: Professor Thomas Michael Will, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548947669

The origin, petrogenesis, tectonic setting(s) and the possible processes responsible for the widespread high-temperature late Carboniferous (<345 Ma) igneous and metamorphic activity during the final stages of the Variscan orogeny are currently debated. Orogenic or anorogenic heat sources are proposed as the ultimate cause of the high thermal regime. The main focus of this proposal is to test these propositions. The occurrence of late orogenic UHT crustal rocks (> 900 °C) is a hallmark of the European Variscan orogenic belt. The expected results of the study may also solve the question why such rocks are present in the Variscan orogen but, to our knowledge, not in other Phanerozoic orogens. We plan to investigate Carboniferous igneous and high-grade metamorphic rocks from various tectonostratigraphic zones of the central European Variscides, including the (i) Saxo-Thuringian Zone (Fichtelgebirge, Erzgebirge, and the Lusatian Mountains), (ii) Mid-German Crystalline Zone (Odenwald, Spessart, Ruhla) and, (iii) the Bavarian high-temperature domain at the western margin of the Moldanubian and Saxothuringian zones by a combination of various methods. These include literature survey, fieldwork, petrography (microscopy), petrology (geothermobarometry, phase diagram studies), geochronology (SIMS U-Pb zircon, rutile and monazite age dating), geochemistry (major, minor and trace element studies) and isotope geochemistry (whole rock Sr-Nd-Pb and zircon Hf-O analyses). Using the new data we plan to constrain the petrogenesis of the rocks and the likely tectonic settings in which they formed and to infer the processes that were involved in their formation. This broad methodological approach, the large extent of the field area (including several tectonostratigraphic zones and their terrane boundaries) and a comparison with, and incorporation of, already existing data should lead to a better understanding of the late Variscan orogeny. The results may also help to unravel the cause of the c. 30 myr lasting high-temperature regime at the end of the Variscan orogeny.

• DFG Programme: Research Grants
• International Connection: China, South Africa, Sweden
• Cooperation Partners: Petrus Le Roux, Ph.D.; Professor Dr. Qiuli Li; Dr. Xiaoxiao Ling; Professor Dr. Uwe Ring