Magmatic and hydrothermal prerequisites for porphyry-epithermal mineralisation in continental volcanic arcs, Thrace, NE Greece

• Applicant: Dr. Manuel Keith
• Subject Area: Mineralogy, Petrology and Geochemistry ; Palaeontology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441174393

Supplying critical and energy critical elements for the green transition is a growing challenge. Many of these metals and metalloids have a strong by-product dependency and their supply therefore depends on the primary target commodities. The strong impact of these elements on the energy and economy sector of the European Union gives them a strategic importance. Thus, the dependency on mining countries like China must be reduced to secure the future supply of raw materials, since their import from these countries may be at risk because of political tensions leading to bottlenecks in the supply-chain. In this respect, the European continent needs to be re-explored to constrain economic zones enriched in critical and energy critical elements. The deposits of Thrace, NE Greece, represent such an example, where zones with high metal and metalloid concentrations (e.g., Cu, Ga, Ge, Se, Mo, Sb, Te, Re, Au and Bi) occur at variable crustal depth in a mineralized continental arc setting in Europe. This includes the porphyry environment in the direct vicinity of a magma chamber, as well as shallower epithermal systems with some that may even preserve a surface expression. Regional variations in deposit mineralogy have been observed, but the ore-forming processes of the porphyry-epithermal deposits are still poorly constrained from a trace element perspective. The magmatic and hydrothermal prerequisites that lead to the formation of such a mineralised arc system are also still controversial, but essential to discover positive anomalies of critical and energy critical elements in the continental crust. The trace metal and metalloid composition of associated plutonic and volcanic/sub-volcanic rocks will provide new results on the magmatic processes in the deeper crust and the potential loss of these elements during magma ascent towards the surface; into regions where they may feed an overlying porphyry-epithermal system. This allows to investigate the effect of magma degassing, as well as sulphide saturation and segregation to form a pre-concentrate in the mid- to lower crust, as possible magmatic prerequisites for arc mineralisation. Pyrite and magnetite occur in most metal-bearing veins in the overlying hydrothermal system. High-resolution trace element analyses on these minerals will provide insights into the processes of ore-formation from a 3D perspective, i.e. in a stratigraphic and regional context. The (in situ) S isotope composition of hydrothermal pyrite will help to better understand the interaction processes between the magmatic and hydrothermal system. Hence, the combined investigation of magmatic and hydrothermal processes makes this approach unique and will help to develop new fundamental concepts with respect to S and metal sourcing, fractionation and precipitation, which ultimately defines the magmatic and hydrothermal prerequisites for continental volcanic arc mineralisation and energy critical element enrichment in Europe.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2238: Dynamics of Ore-Metals Enrichment - DOME
• International Connection: Greece
• Cooperation Partners: Professor Dr. Vasilios Melfos; Professor Dr. Panagiotis Voudouris