04/07/2024

M.Sc. Robert Šamarija

4:00 pm

The Dinarides are a mountain range located along the eastern shore of the Adriatic Sea, which formed mainly during Cretaceous – Paleogene times as a result of the collision between the African and Eurasian plates. During the Miocene, a series of long – lived lakes developed within the intramontane depressions, known as the Dinarides Lake System. The Sinj Basin is one of the best studied among them, providing valuable insights into the paleogeographic evolution of the region. A chronostratigraphic framework was initially established in the NW part of the basin using paleomagnetic data and calibrated by Ar-Ar dating of intercalated volcaniclastic deposits. However, the tectonic setting and timing of deposition are still a matter of debate, as subsequent U-Pb dating of Miocene bauxites in the SE part of the basin demonstrated that lacustrine flooding was diachronous. This study aims to provide new constraints on the evolution of the Sinj Basin based on U-Pb zircon geochronology of volcaniclastic deposits from the NW, central, and SE parts of the basin. After the separation of the heavy-mineral fraction from the samples, individual zircon grains were handpicked using a binocular microscope. U-Pb isotope analyses were obtained using laser ablation‑inductively coupled plasma mass spectrometry (LA–ICP–MS). The obtained ages ranging between ~18 and ~15 Ma provide new constraints on the timing of initial lacustrine flooding, and will aid paleogeographic and paleoenvironmental reconstructions of the Dinarides during the Miocene. In addition, a wide spectrum of detrital zircon ages was obtained, reflecting the pre-Miocene geodynamic history of the Dinarides.