Paleoenvironmental Evolution and Provenance Shifts in Campanian Marginal Gosau Basins: Evidence from Sedimentary and Geochemical Records

The paleoenvironmental and provenance evolution of the Campanian Gosau Group sediments at Grünbach-Neue Welt in the Eastern Alps of Austria was investigated across a continuous transition from terrestrial to marine settings during the depositional period, coinciding with the boundary between the Lower and Upper Gosau subgroups. This transition was primarily driven by tectonic subsidence triggered by the northward subduction of the Penninic Ocean along the northern margin of the Austroalpine microplate. The sedimentary successions record depositional and environmental changes associated with subsidence. Integrated lithological, petrographic, paleontological, mineralogical, and geochemical analyses were performed to reconstruct the paleoenvironmental conditions and trace the sedimentary provenance. Paleoenvironmental analysis implied that the Grünbach Formation (upper Santonian to lower Campanian) represents a terrestrial-dominated setting with episodic marine incursions while the overlying lower Piesting Formation (upper Campanian) is dominantly shallow-marine setting with terrestrial input. The shift toward less weathered, coarser detritus sediments across the two formations suggests changes in sediment transport pathways and sources, likely influenced by subsidence, marine transgression, and source areas’ uplift. This study provides valuable insights into the Campanian paleoenvironment and provenance shifts of the Gosau Group, highlighting the complex interplay between subsidence, sea-level fluctuations, and sediment supply. Furthermore, it advances our understanding of how coupled environmental and tectonic processes influenced basin evolution.