Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina beds (Meride Limestone, Monte San Giorgio, Switzerland)

A pioneering analysis of the Ladinian Cassina beds at Monte San Giorgio reveals the presence of a quasi-anaerobic biofacies characterized by monotypic benthic foraminiferal meiofauna, marking the first documentation of such conditions across the entire Monte San Giorgio sequence. This discovery sheds light on the depositional environment of this renowned Lagerstätte, which experienced background sedimentation under anoxic to episodically suboxic seafloor conditions, interspersed with event depositions linked to sediment input and volcanic eruptions. The study also highlights the proliferation of benthic microbial mats, inferred from microfabrics and taphonomic features, which contributed to the exceptional preservation of vertebrate fossils, including new finds of fishes such as Saurichthys and Archaeosemionotus. Additionally, the research provides insights into the shallow-waters of the adjoining Salvatore platform and critically reviews available biostratigraphic data.

Stockar, R. (2010). Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina beds (Meride Limestone, Monte San Giorgio, Switzerland). Swiss Journal of Geosciences, 103(1), 101–119. https://doi.org/10.1007/s00015-010-0008-2