# Quaternary Evolution of Ischia: A Review of Volcanology and Geology
## 4 Discussion and Conclusions  
A reassessment of the volcanological and geological data of Ischia is herein advised, centering on several aspects, which, respectively, affect the volcanology, the geochemistry, the structural geology, and the marine geology and geophysics of Ischia. This reappraisal, coupled with the seismo-stratigraphic data available in previous papers and resumed in this paper, allows discoursing on the Quaternary geologic development of Ischia. It is not easy to give an answer to most of the open questions existing on Ischia. Some open questions are: What genetic model better explains the origin and the evolution of volcanism at Ischia? Which is the relation between tectonics and volcanism? How does mixing phenomena originate? What are the regional implications? etc. We have tried to do it, in this section and in the whole paper, by examining different models existing in literature and with the presentation of data and argumentation in previous sections. Figure 9: Seismic profile L47 (southern Ischia, Punta S. Pancrazio) and corresponding geologic interpretation. Linking the addressed models with the Quaternary geologic evolution of Ischia represents a main issue and novelty of this paper. The information of [PERSON] et al. [23] is in contrast with the earlier ideas of volcanologists on a long phase of quiescence of the eruptive activity of Ischia between 75 and 50 ky B.P. [8; 30]. The alluvial deposits, previously mentioned to foreground an extended pause in the volcanic activity and in related input, have been re-interpreted as pyroclastic deposits. A new volcanological evolution of Ischia during the Late Pleistocene has been declared [23]. The outcropping products include tracbyte and phonolite lava domes, lava and pyroclastic deposits ensuing from a period of time of magmas, discrimination and volcanic eruption. The happening of some scattered volcanic centers fed by magma advises a differentiated magmatic chamber below the region, preceding the MEGT eruption [8]. The S. Angelo tephra and the Tischiello tephra have upheld cierite deposits and block deposits of pyroclastic flux, proposing the intermittent growth and the destruction of the lava domes in the volcanic centers in the southern sector of the island. The volcanic activity, in correspondence with these centers, has created eruptive columns, which have aroused the dispersion of pumices on the whole territory of the island. The paleogeography of that period was unusual compared to the present-day one. The volcaniclastic and marine deposits occurring below the LMEGT (Rione Bocca) have indicated the occurrence of a depression, older than 55 ky B.P. and located in the central sector of the island. This depression was probably encircled by discrete centers (lava domes and pyroclastic fluxes of Carta Romana-Monte Cotto, S. Angelo, M. te Vico and Punta Imperatore). The geophysical data in the western offshore of Ischia [54] have sustained the remnants of a wide complex, which could be the source of some of these eruptions. Ischia could be connected to the mainland by an isthmus that added part of the present-day island of Procida, given the average sea levels were 50-80 m lower than the actual ones. This eruptive phase probably continued up to the eruption of the MEGT (55 ky B.P. ), which controlled the caldera subsidence on the whole island and has partially destroyed the magmatic chamber. This eruption had two phases of emplacement of isphrite deposits, having a thickness higher than 200 m, in the down throwing caldera. The volcaniclastic deposits occurring between the two ignimbrites show that the subsided caldera was open to the sea during the eruption. The most recent eruptive activity of the MEGT (55 ky B.P.) regards a distinct number of phreato-magmatic and magmatic eruptions, which have brought forth eruptive columns and density pyroclastic currents (Capo Grosso, Chiummano and Schiappone eruptions).