GNGTS 2013 - Atti del 32° Convegno Nazionale

has been interpreted to show the main stratigraphic and structural features of the Pozzuoli Gulf, reported in the geologic interpretation (in the lower inset of the figure). The seismo- stratigraphic analysis has allowed to distinguish eight seismic units. The V3 unit is the oldest one (Fig. 3) and has been interpreted as a volcaniclastic unit genetically related to the northern margin of the Pentapalummo Bank, characterized by discontinuous seismic reflectors. It appears involved in compressional deformation in correspondence to the Punta Pennata and Nisida anticlines. The unit is overlain by the G3 unit, a sedimentary unit composed of clastic deposits, ranging in age from 12 and 8 ky B.P. It is characterized by discontinuous to parallel reflectors and synsedimentary wedging and growth contemporary with folding. The dk unit denominates volcanic dykes, categorized by acoustically transparent vertical bodies, locally bounded by normal faults. The overlying G2 unit is the second unit of the basin filling and is a sedimentary unit composed of clastic deposits, ranging in age from 8 and 4 ky B.P. The NYT/PC unit categorizes the pyroclastic deposits of the Neapolitan Yellow Tuff, while the PC unit represents the tuff cones of the Nisida volcanic complex. The G1 unit is represented by a sedimentary unit composed of clastic deposits (4 ky B.P.). The transgressive and highstand deposits have also been identified (Fig. 3). High resolution seismic stratigraphy in correspondence to the Capo Miseno volcanic edifice has also been studied through the geological interpretation of the L67_7 seismic profile. A land-sea correlation of the volcanic sequences of Capo Miseno has been attempted based on seismo-stratigraphic criteria. The Capo Miseno volcanic edifice is composed of stratified yellow tuffs, i.e. the Bacoli-Isola Pennata-Capo Miseno yellow tuffs (Rosi and Sbrana, 1987). Field geo-volcanological survey of the Capo Miseno volcanic edifice (Rosi and Sbrana, 1987) has suggested that these units consist of pumiceous tuffs, regularly stratified and very highly lithified. The mass is formed by layers of pumice set in an altered ashy matrix, frequently vesciculated and pisolitic. The volcanic layers are medium to thickly bedded and are poorly sorted with a stratification ranging from subparallel to low-angle cross bedding. At the Capo Miseno tuff cone the sedimentary structures include gravity flowage ripples and slumping. Field observation suggests the emplacement of muddy material from wet eruptive clouds, resulting from hydromagmatic activity (Rosi and Sbrana, 1987). The presence of both massive and cross-bedded layers suggests the eruption of alternating pyroclastic flow and wet surges. The offshore elongment of the Capo Miseno-Isola Pennata and Bacoli yellow tuffs is represented by a thick volcanic unit, acoustically transparent and exposed over a large area and identified offshore the Capo Miseno volcanic promontory. The unit is interpreted as genetically related to the yellow tuffs cropping out onshore. On the slopes of the volcanic bank, deformed by normal faulting, the seismic unit is put in lateral contact with a pyroclastic unit, characterized by discontinuous and sub-parallel seismic reflectors. Tectonic setting. The tectonic setting of the Pozzuoli seismic units is herein briefly discussed. The V3 volcaniclastic unit is intensively deformed in correspondence to three anticlinalic structures in the Gulf of Pozzuoli, respectively named the Punta Pennata anticline, the Pozzuoli anticline and the Nisida anticline. The same unit is deformed in correspondence to two synclines, namely the central syncline of the Pozzuoli Gulf and the Epitaffio syncline, individuated due to the compressional deformation genetically related to the main magmatic events of the Phlegrean Fields volcanic complex. The G3 sedimentary unit is strongly involved by wedging and growth in correspondence to older anticlines, involving the V3 unit and related synclines. The deposition of the pyr1 unit, pyroclastic in nature, is controlled by normal faulting, since it has been deposited in a structural depression located under the Capo Miseno volcanic edifice. The dk volcanic unit is represented by several dykes whose emplacement has been controlled by normal faulting in the eastern and central Pozzuoli Gulf, inducing the magma uprising along preferential pathways represented by tectonic lineaments. The pyr2 pyroclastic unit has been deposited in the eastern Pozzuoli Gulf, where it is involved by wedging and growth, testifying its deposition during vertical down throwing of normal 9 GNGTS 2013 S essione 3.1