Sedimentology and micropaleontology of the core G93-C27 (Gaeta bay, central Tyrrhenian Sea, Italy)

A sedimentological and micropaleontological study was carried out on the core G93-C27 from the continental shelf of the Gaeta bay (central Tyrrhenian Sea). Grain-size analysis allowed to distinguish a lower portion, consisting of silty-sandy sediments, and an upper one consisting of sandy-silty sediments. The passage between these two parts occurs at 55 cm from the top, and coincides with a scoured base level particularly rich in bioclasts. The bioclastic content tends to decrease from this level toward the top of the core. Sedimentological parameters and optical microscopy observations allow to ascribe the older sediments to a nearshore environment and the younger sediments to an offshore setting. Frequency oscillations of benthic foraminifera indicate that the lower portion of the core (up to 55 cm from the top) is characterized by species which commonly occur on sandy bottoms of the infralittoral zone, whereas species typical of muddy bottoms of the circalittoral and bathyal zones are dominant in the upper part. This bathymetric and environmental change could record the passage from a regressive phase, which can be ascribed to the last eustatic lowstand (about 18 kyrs B.P.), to a subsequent eustatic rise.