Dating the Miocene arid phase in the Dinarides: new inferences from the Valjevo-Mionica Basin, Serbia

  • Datum:

    31/10/2024

  • Referent:

    M.Sc. Robert Šamarija

  • Zeit:

    16:00 Uhr

  • The Dinarides are a mountain chain located along the eastern coast of the Adriatic Sea, formed during long-lasting convergence and continental collision of the Adriatic microplate (Adria) and the southwestern margin of Eurasia. In the Miocene, extensional tectonics contemporaneous with the opening of the Pannonian Basin affected a large part of the Dinarides and contributed to the widespread development of lake basins. Basins belonging to the Dinarides Lake System (DLS) are characterized by frequent coal intercalations, suggesting warm and humid conditions, whereas basins belonging to the Serbian Lake System (SLS) contain evaporites suggestive of an arid climate. This indicates that topographic uplift of the Dinarides possibly contributed to the establishment of contrasting climatic conditions across the range during the Miocene. However, correlations are complicated by poor age constraints of basins belonging to the SLS. Therefore, we conducted fieldwork and core logging in the Valjevo-Mionica Basin in western Serbia in order to better constrain the age of arid conditions recorded therein. The basin fill consists of polymict conglomerates and sandstones in the lower part, followed by laminated marls with microbial mat intercalations and tufa deposits. In the middle part, laminated to massive marls predominate. The upper part is composed of dolomitic marlstones with evaporite minerals and sandstone intercalations, pointing to an arid climate. Radiometric dating of intercalated volcanic ash horizons enabled us to correlate different successions across the basin, and constrain the duration of the lacustrine phase to between ~14.5 and ~12.6 Ma. These data will help to improve the stratigraphic subdivision of the basin. Moreover, the obtained radiometric ages are vital for correlations of Miocene fossil faunas across the Dinarides. Finally, the ages indicate that the arid conditions recorded in the Valjevo-Mionica Basin were not contemporaneous with the humid conditions recorded in the DLS.
  • Seite:

    16:00h