Multi-proxy analysis in defining sedimentary processes in very recent prodelta deposits: the Northern Phlegraean offshoreexample (Eastern Tyrrhenian Margin)

Abstract

A multi-proxy analysis of Volturno River prodelta deposits in the outer shelf of Northern Phlegraean margin (Eastern Tyrrhenian Sea) has been carried out to reconstruct the sedimentary processes acting during recent times. The late Holocene sediments were characterized through Subbottom Chirp profiles coupled with sedimentological and petrophysical data. The chronostratigraphic framework was achieved by means of colorimetric parameter a* correlations with nearby dated marine sediment. A time interpretation of about 2,300 years BP is estimated for the sedimentary record collected in the cores. Seismic stratigraphic analysis shows late Holocene outer shelf deposits, characterized by fluid escape features and small-offset faults. However, the undisturbed sedimentation and the preservation of an internal geometry at decimetre scale, as detected by the sedimentological and petrophysical analysis, indicates a slow sliding without sediment reworking for this sedimentological body. So far a possible recent (\2,300 years BP) shear dominated downward displacement of high water content sediments, triggered by the occurrence of seismic activity, is inferred. Based on the depth-age conversion of the detected lithological features, a regular climatically driven change in the sediment supply of the prodelta depositional environment is suggested. The detection of spectrophotometry correlations of Holocene shelf margin sediments, several km apart, goes beyond the previous work and confirms even for continental shelf area the potential value of spectrophotometer data in high-resolution stratigraphic correlations