Geochemical Evidences that Unrest at Campi Flegrei Resurgent Caldera (Southern Italy) Is Due to Magma Emplacement and Degassing at Shallow Depth Plus Fluxing from a Deep-Seated Regional Body

摘要

Volcanic calderas are affected by unrest episodes usuallydominated by hybrid magmatic-hydrothermal systemdynamics. Unrest episodes can evolve to eruptionsof variable intensity, up to Plinian. Campi Flegrei caldera(CFc) is a type-location for this kind of activity escalation.CFc offers unique opportunity to join volcanologicalinformation to a long record of geochemical parameters.This allows understanding the role that magmaticsystem plays on variations displayed by the hydrothermalsystem. We model uneruptive unrest episodes asdriven by i) the shallow emplacement (~4 km depth) ofone volatile-rich magma batch ascending from a deep(≥ 8 km) magmatic body of regional extent, ii) subsequentgas separation with degassing driven by crystallizationand iii) fluxing from the deep magmatic body.Our model matches three decades of geochemical constraintsfrom fumarole discharges, as well as data from melt inclusions of past CFc eruptions. Besides, magmaphysical properties demanded for modeled degassingconditions are in good agreement with existing geophysicaldata. Our results open new perspectives to thedefinition of unrest scenarios at highly-populated CFc,as well as other resurgent calderas (e.g., Orsi et al., ThisAssembly).