Sequence stratigraphy of Cretaceous carbonate platforms: a cyclostratigraphic approach

Textures and early diagenetic features of Cretaceous carbonate platform deposits from central and southern Italy have been analyzed at centimetre to decimetre scale, along well exposed outcrops and in bore cores. The studied sections, despite lack of evident progradational and retrogradational geometries, show systematic variations in facies and bed thickness that evidence cyclic environmental oscillations. A hierarchy of cycles (elementary cycles, bundles and superbundles) has been recognized. Eustatic-climatic, high-frequency changes, linked to the Earth’s orbital perturbations, are considered at the origin of this hierarchy, where the elementary cycles record the precession and/or the obliquity periodicities, and the bundles and superbundles record the short- and long-eccentricity, respectively. These orbital cycles are superimposed on lower-frequency cycles (Trangressive/Regressive Facies Trends, T/RFTs), commonly made up of 2-5 superbundles.
In a sequence stratigraphy approach, the superbundles and the T/RFTs have been interpreted in terms of depositional sequences and used for high-resolution, long-distance (regional- to supraregional) correlation, as well as to assemble orbital chronostratigraphic diagrams that quantify the minimum time required for each succession to stack up.
The chronostratigraphic correlation carried out in central-southern Italy allowed us to show that the sedimentary record of the analyzed sequences may be considered quasi-continuous, at least at superbundle level, and to suggest numerical estimates for the time duration of the discussed intervals.

Keywords: Cyclostratigraphy, Sequence stratigraphy, High-resolution correlation, Orbital chronostratigraphy.