Miocene tuffs from the dinarides and eastern alps as proxies of the pannonian basin lithosphere dynamics and tropospheric circulation patterns in central europe

Tuffaceous layers are regularly preserved in Miocene carbonate and siliciclastic sediments of the Dinarides and Eastern Alps in southeastern and central Europe. Detailed mineralogical and geochemical analyses of 13 tuffs of known ages acquired from sedimentary successions of the intramontane Dinarides basins and the southwestern Pannonian Basin were carried out to infer on plausible source areas, relative strengths of volcanism, and ash distribution patterns. Studied tuffs were altered to various degrees with illite–smectite and smectite as dominant phases while volcanic glass, carbonates and other silicates are minor constituents. Tuffs’ compositions range from andesite through trachyandesite to rhyolite and trachyte. Trace-element-based correlation with regional data reveal that Lower Miocene (LM) and Lower Middle Miocene (LMM) tuffs (17.0–14.0 Ma) likely originated in the Western Carpathians (the Bükkalja volcanic field) while source areas of Upper Middle Miocene (UMM) tuffs (13.8–12.5 Ma) were in the Apuseni Mountains and/or Eastern Carpathians. The spatial relation of LM/LMM and UMM tuffs with respect to their source areas (the Bükkalja volcanic field and Apuseni Mountains, respectively) is most consistent with tropospheric easterly trade winds that carried ash hundreds of kilometres to the SW toward an azimuth of c. 200–250°.