Ichnocoenoses in the Oligocene to Miocene foredeep basins (Northern Apennines, central Italy) and their relation to turbidite deposition

Abstract

Analysis of trace fossil abundance and diversity in the Oligocene to Miocene foredeep and piggyback basins of the Tuscan–Romagna–Umbrian Apennines allows us to recognize five ichnocoenoses. The deposits reflect sedimentary environments from slope to basin plain, whose sedimentation was directly controlled by synsedimentary tectonics: attached fan lobes and channels, lobe- and channel-fringes, overbank-fringes of intrabasinal highs, distal detached lobes of basin plain and slope-proximal interfans. The graphoglyptid:non-graphoglyptid ratio has been considered as the chief factor in the study of ichnologic material from Falterona–Cervarola–Trasimeno, Marnosoarenacea and Marne di Vicchio-Verghereto stratigraphic units. The study shows that there is an increase in ichnodiversity and ichnodensity of graphoglyptids, which are typical mainly in detached lobes of basin plain and overbank-levee deposits whose background ichnofauna also shows better preservation.