"Il Calcare a Lucina pomum”della Successione Epiligure dell’Appennino modenese: stratigrafia, sedimentologia e dati geochimici.

In this paper "Lucina limestones", outcropping in the Modena area, where for the first time were found, are investigated from a stratigraphical, sedimentological and geochemical viewpoint. The data collected allow these deposits to be ascribed to the Termina Formation of the Epiligurian Sequence and to be dated at the top of the Upper Serravallian. Different outcrop types are recognized: 1) marly-calcareous lenses with lucinids, 2) marly-calcareous and calcarenitic hectometric levels with lucinids, 3) marly-calcareous breccias with lucinids. The first two outcrop types clearly show show evidence of a primary deposition and gradually pass to surrounding pelitic marls, whereas the third one is resedimented. The sedimentological and stratigraphical results obtained from this research permit to differentiate the numerous "Lucina deposits" reported in literature. Geochemical and taphonomic analyses confirm the stratigraphical and sedimentological data and lead to interpret the lucinid assemblages of the Modena territory deposits as chemosynthetic communities related to hydrocarbon sources. A methanogenic hypothesis, different from those commonly reported in literature, is here proposed which considers lucinid chemoherm as derived from local bacterical oxidation of marly-pelitic sediments