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

摘要

The world-famous "Pesciara di Bolca" Fossil-Lagerstatte 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. (c) 2006 Elsevier B.V. All rights reserved.