Hydrothermal fluid venting in the offshore sector of Campi Flegrei caldera: A geochemical, geophysical, and volcanological study

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• 作者：R. Di Napoli ; A. Aiuppa ; A. Sulli ; S. Caliro ; G. Chiodini ; V. Acocella ; G. Ciraolo ; M.A. Di Vito ; F. Interbartolo ; C. Nasello ; et al
• 刊名：Geochemistry, Geophysics, Geosystems
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：17
• 期：10
• 页码：4153-4178
• 全文大小：8.7MB
• ISSN：1525-2027

文摘

The ongoing unrest at the Campi Flegrei caldera (CFc) in southern Italy is prompting exploration of its poorly studied offshore sector. We report on a multidisciplinary investigation of the Secca delle Fumose (SdF), a submarine relief known since antiquity as the largest degassing structure of the offshore sector of CFc. We combined high-resolution morphobathymetric and seismostratigraphic data with onshore geological information to propose that the present-day SdF morphology and structure developed during the initial stages of the last CFc eruption at Monte Nuovo in AD 1538. We suggest that the SdF relief stands on the eastern uplifted border of a N-S-trending graben-like structure formed during the shallow emplacement of the Monte Nuovo feeding dike. We also infer that the high-angle bordering faults that generated the SdF relief now preferentially allow the ascent of hot brines (with an equilibrium temperature of 179°C), thereby sustaining hydrothermal degassing on the seafloor. Systematic vertical seawater profiling shows that hydrothermal seafloor venting generates a sizeable CO₂, pH, and temperature anomaly in the overlying seawater column. Data for the seawater vertical profile can be used to estimate the CO₂ and energy (heat) outputs from the SdF area at ∼50 tons/d (∼0.53 kg/s) and ∼80 MW, respectively. In view of the cause-effect relationship with the Monte Nuovo eruption, and the substantial gas and energy outputs, we consider that the SdF hydrothermal system needs to be included in monitoring programs of the ongoing CFc unrest.