The Proximal Marine Record Of Somma-vesuvius Volcanic Activity In The Naples And Salerno Bays, Eastern Tyrrhenian Sea, During The Last 3 Kyrs

摘要

The tephrostratigraphic analysis of nine gravity cores acquired on the continental shelf of the Naples and Salerno bays documents the proximal record of Somma-Vesuvius volcanic activity during the latest Holocene (last 3 kyrs). Five tephra layers from southern Naples Bay and three tephra layers from northern Salerno Bay were recognised in cores and their sedimentologic structures, textural parameters, stratigraphy and major and trace-element composition described. Proximal products of the well known 79 A.D. eruption along with those of the interplinian activity at 2.7 ka B.P., were identified both in the southern Naples Bay and in the northern Salerno Bay. They represent excellent marker horizons interbedded within the Late Holocene marine record. In addition, several radiocarbon datings provided age constraints on a number of tephras overlaying the 79 A.D. deposits and allowed a detailed stratigraphic reconstruction of medieval (1137 A.D.-685 A.D.) and more recent eruptions as recorded for the first time at sea. These results integrate previous research carried out on subaerial deposits providing new insights on the dispersion, deposition and grain-size distributions, along the northern Campania coastal zone, of recent Somma-Vesuvius products, some of which are still poorly known. The tephrostratigraphic approach to the study of marine sequences of proximal and adjacent areas can thus provide a more detailed description of physical characteristics of pyroclastic deposits, necessary for the correct assessment of volcanic hazard in the area.