Suchergebnisse

The prehistoric (< 7 ka) Zaro eruption at Ischia island (Southern Italy) produced a lava complex overlaying a pyroclastic deposit. Although being of low energy, the Zaro eruption might have caused casualties among the neolithic population that inhabited that area of Ischia, and damages to their settlements. A similar eruption at Ischia with its present-day population would turn into a disaster. Therefore, understanding the magmatic processes that triggered the Zaro eruption would be important for volcanic hazard assessment and risk mitigation, so as to improve a knowledge that can be applied to other active volcanic areas worldwide. The main Zaro lava body is trachyte and hosts abundant mafic and felsic enclaves. Here all juvenile facies have been fully characterized from petrographic, geochemical and isotopic viewpoints. The whole dataset (major and trace element contents; Sr-Nd isotopic composition) leads to rule out a genetic link by fractional crystallization among the variable facies. Thus, we suggest that the Zaro mafic enclaves could represent a deep-origin mafic magma that mingled/mixed with the main trachytic one residing in the Ischia shallow magmatic system. The intrusion of such a mafic magma into a shallow reservoir filled by partly crystallized, evolved magma could have destabilized the magmatic system presumably acting as a rapid eruption trigger. The resulting processes of convection, mixing and rejuvenation have possibly played an important role in pre- and syn-eruptive phases also in several eruptions of different sizes in the Neapolitan area and elsewhere in the world. ; The authors are grateful to Roberto de Gennaro for his precious help in obtaining SEM-EDS-WDS data. This study was carried out in the framework of the GEOPAM Research Group (AGAUR, Generalitat de Catalunya, Ref. 2017 SGR 1494). We acknowledge the technical support of M. Rejas of ICTJA-CSIC Laboratory of Geochemistry labGEOTOP, infrastructure co-funded with resources from the ERDF, European Union, (CSIC08-4E-001, and partner of Project EPOS Implementation Phase, EPOS IP, Grant Agreement no. 676564-EPOS IP Call H2020-IFRADEV-12015-1). The INGV, OV laboratories have been financially supported by the EPOS Research Infrastructure through the contribution of the Italian Ministry of University and Research (MUR). Reviews by Prof. Dr. Gerhard Franz, as well as comments and suggestions by the Editor, greatly contributed to the improvement of the original manuscript and are kindly acknowledged. Funding Open access funding provided by Università degli Studi di Napoli Federico II within the CRUI-CARE Agreement ; Peer reviewed