New Data about the Age and Palaeoenvirnment of the “Pesciara di Bolca” Fossil-Lagerstätte

The “Pesciara di Bolca” (Verona Province, Northern Italy) is one of the most famous fossil-lagerstätten, known since the mid XVI century for its spectacularly-preserved fish faunas. The latter were extensively studied during past years (e.g. Sorbini, 1972), but little or no attention at all was deserved to the invertebrate microfauna (especially foraminiferans) and to the facies analysis.The larger foraminiferans present in the Pesciara succession were since now neglected because, showing signs of transport, they were considered as reworked. A careful analysis of the field and microfacies features allowed us to conclude the foraminiferans are certainly mostly transported, but with no signs of a real reworking. Moreover, the alveolinas assemblages from all the collected samples belong to the same biozone (Alveolina dainellii Zone, SBZ 11 or Middle Cuisian). The only exception regards some extraclasts in the lower portion of the succession, where silicified alveolinas indicate the underlying SBZ 10 (Alveolina oblonga Zone, Early Cuisian).Previously, the age of the Pesciara was given as Early-Middle Eocene, relying on a single-sample attribution to the nannoplankton zone NP 14 (Discoaster sublodoensis Zone; Medizza, 1975). Now, the alveolina assemblages recognized over the whole succession allow a more stable datation.The facies analysis allowed us to distinguish between strictly autochthonous micritic limestones and allochthonous biocalcarenites-biocalcirudites. The former represents the fish-bearing levels, probably settled within an oxygen-depleted paleoenvironment accounting for the exceptional preservation of fossils. The latter, containing the larger foraminiferans, were probably the result of storm-induced transport from nearby very shallow sea bottom.The presence of emerged lands close to the Pesciara “basin” is testified by several continental fossils of both plants and animals (especially insects). The recent discovery of amber within the Pesciara limestones reinforces this interpretation (Trevisani et al., 2005, in press).ReferencesMedizza F (1975) Il nannoplancton calcareo della Pesciara di Bolca (Monti Lessini). St Ric Giacim Terz Bolca 2:433-444Sorbini L (1972) I fossili di Bolca. Mus Civ St Nat Verona, Verona, 133 ppTrevisani E, Papazzoni CA, Ragazzi E, Roghi G (2005) Early Eocene amber from the “Pesciara di Bolca” (Lessini Mountains, Northern Italy). Palaeogeogr Palaeoclimatol Palaeoecol, in press