Sedimentology and high-resolution sequence stratigraphy of a lower Cretaceous shallow-water carbonate succession from the Western Gargano Promontory (Apulia, Southern Italy)

Detailed facies analysis of a lower Cretaceous shallow-water carbonate succession cropping out in the western Gargano Promontory (Apulia, southern Italy) reveals a complex stacking of depositional sequences. The organization of lithofacies associations in beds and bedsets allowed us to identify 43 elementary sequences grouped in 12 small-scale sequences forming 4 medium-scale sequences. This hierarchical organization of the sequences is interpreted as being related to composite relative sea-level changes probably driven by the Earth’s orbital perturbations in the Milankovitch frequency band.
Sequence-stratigraphic concepts were applied to all orders of sequences. Transgressive and regressive trends in vertical evolution of lithofacies and groups of lithofacies, as well as the repetition of diagnostic surfaces or intervals, are interpreted as sequence boundaries, transgressive surfaces or maximum flooding zones, allowing identification of depositional sequences and related systems tracts.
The superposition of relative sea-level changes occurring with different frequencies and amplitudes is described in terms of accommodation changing through time. It is observed that this interaction leads to the internal variability observed in all orders of sequences.
The bulk of the study succession is made up of deposits formed during medium-scale late transgressive to early highstand periods. During these phases, thick small-scale sequences, made up of a great number of elementary sequences, are recorded in the succession, suggesting a general increase in accommodation. On the other hand, during medium-scale early transgressive and late highstand periods, small-scale sequences are thinner and show a lower number of elementary sequences, suggesting a general loss in accommodation.

Keywords: Inner-shelf carbonate, Relative sea-level change, High-resolution sequence stratigraphy, Early Cretaceous, Gargano Promontory.