Cretaceous to Miocene Sequence Stratigraphy and Evolution of the Maiella Carbonate Platform Margin, Italy

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Abstract
Sequence and biostratigraphic analysis of the margin of the Apulian carbonate platform in the Montagna della Maiella (central Italy) reveal a platform margin evolution that is controlled by long-term sea-level changes, tectonism and changing platform morphology. The Upper Cretaceous to Miocene strata can be subdivided into six supersequences that are separated by deeply incised truncation surfaces. Biostratigraphy documents a major hiatus for all but one of these boundaries. The supersequences reflect distinct stages of platform development, thus the depositional systems remained the same within each supersequence but changed across the supersequence boundaries. The Apulian platform grew on a passive margin of the Jurassic-Cretaceous (Neo-) Tethys. During the early platform history, subsidence rates decreased exponentially with time and controlled the long-term aggradation potential of the platform. The generally decreasing total subsidence rates permitted the basin in front of the platform to be filled up by the Late Campanian strata (Supersequence [SS] 1), resulting in a change from aggradation to progradation. This enabled slope carbonates of Late Campanian to Late Eocene age (SS 2 to 4 and lower part of SS 5) and finally shallow-water platform carbonates of Late Eocene to Late Miocene age (upper part of SS 5 to SS 6) to prograde basinwards. The supersequence boundaries are to a large extent controlled by long-term (2nd-order) eustatic sea-level changes, but climate and tectonism influenced their duration and expression. Climate, initially tropical to subtropical but temperate in Miocene time, and the respective evolution of flora and fauna were major controls on sequence architecture but did not significantly influence the formation of the supersequence boundaries. The tectonic movements related to Alpine orogeny and foreland basin development were not able to completely obliterate the long-term eustatic signal but greatly enhanced the boundaries, although the exact amount of this influence cannot be assessed. Platform morphology was very influential on sequence architecture. From at least Early Cretaceous to Late Campanian time, the presence of a steep escarpment resulted in detached sequences, consisting of an onlapping basinal part and an aggrading part on the platform top, separated by a bypass slope. In Late Campanian to Oligocene time, a distally steepened slope profile was deeply incised, most pronounced along the platform margin and the upper slope, during 2nd-order sea-level lowstands. Sea-level fluctuations along the gently inclined Miocene shelf resulted in deposition of deepening-upward sequences under conditions of low carbonate productivity.

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