Statistical analysis of bed-thickness variation in a Tortonian succession of biocalcarenitic tidal dunes, Amantea Basin, Calabria, southern Italy

The statistical tests indicate that the axial zone and inner flank of the tidal complex show alternating clusters, 5-15 m thick, of thinner and thicker beds, whereas the outer flank and marginal zone show thinning-upward bed packages, 15-25 m thick. An overall thinning-upward trend characterizes the transitional flank zone. The bed packages are considered to form aggradational parasequences, whose varied lateral development is attributed to a differential response of the subtidal system to bathymetric changes. The data set indicates that the bed thicknesses are self-similar, but beds thinner than 250 cm have a different fractal dimension than the thicker beds. The pattern of bed-thickness variation is considered to be a result of internal forcing of a sedimentary system in a state of self-organized criticality, perturbed by bathymetric changes. Fractal property bears important implications for the spatial characteristics of sedimentary succession, allowing bed geometries and volumes to be assessed on the basis of thickness data from isolated logs or drilling cores.