Sedimentary and Geochemical Records of Paleoenvironmental transition in the Campanian Gosau Group, Grünbach-Neue Welt, Austria

In Grünbach-Neue Welt (Lower Austria), the Campanian portion of the Gosau Group is exposed along the boundary between the Northern Calcareous Alps and the Vienna Basin, including the Grünbach Formation (Lower Campanian) and the Piesting Formation (Upper Campanian). The paleoenvironment exhibits transitions from terrestrial to shallow marine settings, driven primarily by subsidence and relative sea-level fluctuations. However, the detailed processes governing this depositional environment transition have not been thoroughly studied. To address this gap, this study collected sediment samples from the transitional section across the two formations, including two artificial trenches and one outcrop in Maiersdorf, as well as one outcrop in the Lupard Quarry. Lithological, paleontological, mineralogical, and geochemical characteristics were analyzed comprehensively to reconstruct the paleoenvironmental evolution. The upper Grünbach Formation, characterized by variable clastic beds interspersed with coal layers, was deposited in a predominantly terrestrial environment with occasional marine influences. In contrast, the lower Piesting Formation, composed of fine- to coarse-grained sandstones containing orbitoids and bivalve fragments, indicates deposition in a shallow marine environment. Geochemical analyses corroborate the environmental transition of the strata, highlighting a shift from terrestrial conditions with intermittent marine influences to a shallow marine setting with ongoing terrestrial input. The sediment source remained strongly altered and relatively consistent during the mid-Campanian, although changes in depositional environment and the effects of marine transgression likely affected sediment composition. This study provides a detailed examination of the paleoenvironmental and provenance characteristics of the Campanian Gosau Group in Austria. It offers better insights into the change of depositional environments driven by tectonic subsidence, sea-level fluctuation, and associated marine transgressions during the Campanian.