Tephrochronology and Geochemistry of Tephra from the Campi Flegrei Volcanic Field, Italy

Abstract

AbstractLayers of volcanic ash (tephra) can be used as isochronous markers linking different sedimentary archives and allowing detailed analysis of the relative timing of climatic or evolutionary events. Conversely, high-resolution sedimentary tephra archives can shed light on the geochemical evolution of magmatic systems. The last ~110 kyrs of activity at the Campi Flegrei volcanic field is punctuated by several large eruptions, including the caldera forming Campanian Ignimbrite (~40 ka) and Neapolitan Yellow Tuff (~15 ka) eruptions and the more recent Pomici Principali (~12.1 ka) and Agnano-Monte Spina (~4.5 ka) all of which are preserved in distal settings several hundred kilometres away. In addition, there are a number of important distal Campi Flegrei caldera tephra layers for which the source eruption is not known (X-5 at ~105 ka and X-6 at ~109 ka) or only recently established (Y-3; ~29 ka), indicating the occurrence of large eruptions that are unknown or poorly constrained from proximal deposits. In this contribution we discuss the dispersal and age significance of these 7 key Campi Flegrei caldera eruptions. The value of distal tephra layers is dependent on the ability to identify a distinctive geochemical fingerprint for each layer, for example, the Campanian Ignimbrite and Neapolitan Yellow Tuff events tapped zoned magma chambers and thus produced unique and compositionally variable tephra layers. Micron-beam major and trace element analyses of distal and proximal volcanic glasses allow direct distal-distal and proximal–distal tephra comparisons. In addition, good stratigraphic and chronological control is important in order to identify and correlate tephra with confidence. Here, we discuss the distinctive geochemical compositions of each of the 7 highlighted Campi Flegrei caldera marker tephra layers.