A reef coral in the condensed Maiolica facies on the Mt Nerone pelagic carbonate platform (Marche Apennines): The enigma of ancient pelagic deposits

Abstract

A coral interpreted as a shallow-water zooxanthellate (z-) form has been recovered from the uppermost part of a condensed, pelagic carbonate platform-top succession, in levels with transitional characters between the Jurassic Bugarone Group and the Maiolica Formation, a calpionellid-bearing pelagic deposit. While the existence of z-corals in the Jurassic pelagic facies of northern Apenninic structural highs is well documented, with early Tithonian forms diagnostic of the lower layers of the photic zone, the species described in this paper is slightly younger (late Tithonian), possesses a different morphology and is known from typical reef facies. While this finding provides welcome evidence for the paleodepth interpretation of otherwise enigmatic facies, it also challenges our understanding of pelagic deposits, in paleoenvironments that have no modern counterparts.