Facies analysis, palaeoenvironmental reconstruction, and biostratigraphy of the “Pesciara di Bolca” (Verona, northern Italy): An early Eocene Fossil-Lagerstätte

The world-famous “Pesciara di Bolca” Fossil-Lagerstätte has been examined in its palaeontological and sedimentological aspects. A re-examination of the co-occurring age-diagnostic larger foraminifers (Alveolina and Nummulites) indicates a SBZ 11 (late Ypresian) age. Sedimentological characters allowed us to distinguish between autochthonous micritic limestones and allochthonous biocalcarenites–biocalcirudites; the latter are the product of penecontemporaneous transport from nearby areas. The depositional model here proposed involves a basin with restricted circulation and a prevailing micrite sedimentation. This basin was affected by relative sea-level oscillations and coarser grained storm-induced deposition. The palaeoenvironmental reconstruction suggests neighbouring emerged land and very shallow sea bottoms inhabited by large foraminifers such as Alveolina and Nummulites. As yet, it is unclear whether a true coral reef was present nearby. The bottom on which the Pesciara deposits accumulated is interpreted as poorly oxygenated, possibly with stromatolite-like bacterial mats, thus allowing the exceptional preservation of the fish and plants.