- 1Institute of Applied Geosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany (nevena.tomasevic@kit.edu)
- 2Chair of Economic Geology and Geochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
- 3Laboratory for Environmental and Raw Material Analyses (LERA), Karlsruhe Institute of Technology, Karlsruhe, Germany
- 4University of Tuebingen, Department of Geosciences, Petrology and Mineral Resources, Tuebingen, Germany
- 5University of Belgrade, Faculty of Mining and Geology, Belgrade, Serbia
- 6MMI Bor Mining and Metallurgy, Bor, Serbia
- 7Institut für Geowissenschaften, Goethe-Universität Frankfurt, Frankfurt, Germany
- 8Frankfurt Isotope and Element Research Center (FIERCE), Frankfurt, Germany
Saline-alkaline lakes commonly occur in semi-arid tectonically active regions, and their deposition is influenced by tectonic, surface and hydrothermal processes, and climate. This study explores the effects of climate and hydrothermal fluid flow on the formation of the saline-alkaline succession of the Ibar Basin, southern Serbia, using sedimentological analysis, U-Pb geochronology of carbonates (via LA-ICP-MS), geochemistry, and fluid inclusion analysis.
The basin’s predominantly clastic sedimentation includes alluvial fan, floodplain, delta, marginal, and profundal lake facies. Microbiolites and littoral to sublittoral oil shales are deposited in areas lacking the clastic input. Stratigraphically, the basin transitioned from alluvial to lacustrine environments, whose Early to Middle Miocene onset at ~ 17 Myrs is revealed by U-Pb dating of microbiolites.
The hydrologically closed lake phase is associated with borate-rich facies, primarily colemanite with secondary ulexite, within profundal lake settings. Syn-depositional colemanite precipitated near the sediment-water interface in a deep lake environment. Post-depositional colemanite and associated calcite filled the pore space within the microlites or intrabasinal breccias. Primary fluid inclusions in post-depositional colemanite and calcite reveal brine evolution under evaporitic, redox conditions, with diagenetic temperatures reaching 200–220°C.
High Ca²⁺/Na⁺ ratios in the brine promoted colemanite precipitation. Subsequent Ca²⁺ depletion and clay breakdown led to ulexite and borax formation. B, Ca, and Na were transported into the basin by streams carrying weathered volcanic material and thermal fluids leaching basement rocks. The arid climate-induced evaporation-initiated precipitation of syndepositional colemanite, while subsequent enrichment and growth of post-depositional colemanite and calcite were driven by fluid reflux during diagenesis.
How to cite: Andrić-Tomašević, N., Walter, B. F., Simić, V., Raza, M., Životić, D., Novković, Ž., Kolb, J., Gerdes, A., and Beranoaguirre, A.: The role of the arid climate and hydrothermal fluids in depositional processes in saline alkaline lakes: inferences from Ibar intramountain basin (Serbia), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16714, https://doi.org/10.5194/egusphere-egu25-16714, 2025.
