Vlček T., 2026: Evaluating the paleoenvironmental significance of tricyclic terpanes: Evidence from Miocene fine-grained sediments of the Danube Basin (Slovakia). Acta Geologica Slovaca, 18, 1, 15–22.

Evaluating the paleoenvironmental significance of tricyclic terpanes: Evidence from Miocene fine-grained sediments of the Danube Basin (Slovakia)

Tomáš Vlček

Department of Geology and Paleontology, Faculty of Natural Sciences, Comenius University Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia; tomas.vlcek@uniba.sk

Abstract

This study investigates the distribution of tricyclic (C₁₉–C₂₆) and tetracyclic terpanes in thirty fine-grained sediment samples from the Kolárovo-4, Pozba-4, and Zelený háj-1 wells to reconstruct paleoenvironmental conditions in the Miocene Danube Basin in Slovakia (NW Pannonian Basin System). The results reveal clear spatial and stratigraphic variations reflecting the transition from the Sarmatian to the Pannonian stages. In the Middle Miocene (Sarmatian) Vráble Formation, a predominance of C₂₃TT is consistent with marine to saline lacustrine conditions, followed by a shift to fluvial–deltaic and freshwater lacustrine environments with higher C₁₉ and C₂₀ homologs. Within the Upper Miocene Pannonian, the offshore Ivanka Formation shows mixed tricyclic terpane patterns that suggest a transition from marine–brackish to freshwater lacustrine settings. The overlying Upper Miocene Beladice Formation is dominated by C₂₁TT and C₂₃TT, consistent with stable freshwater-influenced delta-plain sedimentation. Overall, tricyclic terpanes represent useful complementary geochemical indicators that, when interpreted together with stratigraphic and sedimentological information, may aid the reconstruction of basin evolution and depositional environments across major paleoenvironmental changes in the Miocene Danube Basin.

Key words: Tricyclic terpanes, Paleoenvironmental proxies, Beladice Fm., Ivanka Fm., Vráble Fm., Depositional environment

Manuskript doručený: 2026-03-19

Manuskript revidovaný: 2026-06-22