Revealing Miocene tectonic-climate interactions in the Dinarides

Mountain building can strongly influence regional climate by modifying atmospheric circulation and precipitation patterns. While such interactions are well documented in major mountain ranges such as the Himalayas and the Andes, their significance in lower ranges remains less well constrained. This work is focused on testing whether the Dinarides modified the regional climate and caused an orographic rain-shadow effect in the Miocene. Previous studies have suggested the existence of contrasting humid and arid environments across the mountain range during this time, accompanied by marked differences in lake development and faunal distribution. However, limited geochronological constraints from the eastern flank of the Dinarides have hindered regional correlations between intramontane basins and mechanisms driving paleoenvironmental variations. Here, we integrate sedimentological, geochronological and paleontological observations from Miocene lacustrine successions across the Dinarides to reconstruct paleoclimatic patterns and their relationship with regional tectonics.

Field investigations were conducted at key successions in western Serbia, focusing on reconstruction of depositional environments through sedimentological observations, and sampling of intercalated volcanic ash layers. From these, zircons were extracted and U-Pb dating was performed by means of LA-ICP-MS. Our results reveal the coeval development of contrasting lake systems during the Middle Miocene. Freshwater lakes dominated the western flank of the Dinarides, facing the Adriatic Sea, whereas saline-type lakes characterized the eastern flank.

We interpret these observations as evidence for a pronounced climatic gradient across the Dinarides during the Middle Miocene Climatic Optimum. The results support the hypothesis that the Dinarides topography acted as an orographic barrier that intercepted moisture-bearing westerly air masses, resulting in enhanced humidity on the windward side and increased aridity on the lee side of the range. At the same time, the magnitude and persistence of these climatic contrasts may have been modulated by global climate change, changes in regional land vs sea distribution, and hydrological changes. Our findings suggest that even relatively modest mountain belts can exert a significant influence on regional climatic development, comparable to patterns observed in larger orogenic systems.