“…Digital rock studies are a powerful tool to quantitatively explore rock microstructure and physical properties in 3D and non-destructively. Investigations mainly focused on sedimentary (especially sandstone and carbonate) rocks so far 11 – 14 but they are rapidly expanding to other types of rocks, including volcanic ones 3 , 29 – 33 . Although several works are now available for unconsolidated volcanic pyroclasts and lavas with relatively simple textures, very few efforts have been done to examine consolidated microporous volcanic rocks 6 , 7 .…”
Section: Resultsmentioning
confidence: 99%
“…1 ). The eruption occurred from the Campi Flegrei caldera (Naples, Italy), one of the most dangerous active volcanic area in Europe 27 – 29 , where surface tuffs are largely widespread and caldera-filling deposits are dominated by subsurface tuffs 5 . Figure 1 Location, distribution, aspect and 3D imaging of Campanian Ignimbrite tuff.…”
Digital rock physics offers powerful perspectives to investigate Earth materials in 3D and non-destructively. However, it has been poorly applied to microporous volcanic rocks due to their challenging microstructures, although they are studied for numerous volcanological, geothermal and engineering applications. Their rapid origin, in fact, leads to complex textures, where pores are dispersed in fine, heterogeneous and lithified matrices. We propose a framework to optimize their investigation and face innovative 3D/4D imaging challenges. A 3D multiscale study of a tuff was performed through X-ray microtomography and image-based simulations, finding that accurate characterizations of microstructure and petrophysical properties require high-resolution scans (≤ 4 μm/px). However, high-resolution imaging of large samples may need long times and hard X-rays, covering small rock volumes. To deal with these limitations, we implemented 2D/3D convolutional neural network and generative adversarial network-based super-resolution approaches. They can improve the quality of low-resolution scans, learning mapping functions from low-resolution to high-resolution images. This is one of the first efforts to apply deep learning-based super-resolution to unconventional non-sedimentary digital rocks and real scans. Our findings suggest that these approaches, and mainly 2D U-Net and pix2pix networks trained on paired data, can strongly facilitate high-resolution imaging of large microporous (volcanic) rocks.
“…Digital rock studies are a powerful tool to quantitatively explore rock microstructure and physical properties in 3D and non-destructively. Investigations mainly focused on sedimentary (especially sandstone and carbonate) rocks so far 11 – 14 but they are rapidly expanding to other types of rocks, including volcanic ones 3 , 29 – 33 . Although several works are now available for unconsolidated volcanic pyroclasts and lavas with relatively simple textures, very few efforts have been done to examine consolidated microporous volcanic rocks 6 , 7 .…”
Section: Resultsmentioning
confidence: 99%
“…1 ). The eruption occurred from the Campi Flegrei caldera (Naples, Italy), one of the most dangerous active volcanic area in Europe 27 – 29 , where surface tuffs are largely widespread and caldera-filling deposits are dominated by subsurface tuffs 5 . Figure 1 Location, distribution, aspect and 3D imaging of Campanian Ignimbrite tuff.…”
Digital rock physics offers powerful perspectives to investigate Earth materials in 3D and non-destructively. However, it has been poorly applied to microporous volcanic rocks due to their challenging microstructures, although they are studied for numerous volcanological, geothermal and engineering applications. Their rapid origin, in fact, leads to complex textures, where pores are dispersed in fine, heterogeneous and lithified matrices. We propose a framework to optimize their investigation and face innovative 3D/4D imaging challenges. A 3D multiscale study of a tuff was performed through X-ray microtomography and image-based simulations, finding that accurate characterizations of microstructure and petrophysical properties require high-resolution scans (≤ 4 μm/px). However, high-resolution imaging of large samples may need long times and hard X-rays, covering small rock volumes. To deal with these limitations, we implemented 2D/3D convolutional neural network and generative adversarial network-based super-resolution approaches. They can improve the quality of low-resolution scans, learning mapping functions from low-resolution to high-resolution images. This is one of the first efforts to apply deep learning-based super-resolution to unconventional non-sedimentary digital rocks and real scans. Our findings suggest that these approaches, and mainly 2D U-Net and pix2pix networks trained on paired data, can strongly facilitate high-resolution imaging of large microporous (volcanic) rocks.
“…This work is part of the INGV research project LOVE-CF (Linking surface Observables to subvolcanic plumbing-system: a multidisciplinary approach for Eruption forecasting at Campi Flegrei caldera (Italy). Petrological and geochemical data are available through Pappalardo and Buono (2021) and Chiodini et al (2021). Open Access Funding provided by Istituto Nazionale di Geofisica e Vulcanologia within the CRUI-CARE Agreement.…”
Section: Acknowledgmentsmentioning
confidence: 99%
“…Consideration of all available petrological data for Campi Flegrei volcanic products, has suggested the existence of a multidepth magmatic system (e.g., Pappalardo & Buono, 2021 and references therein), constituted by a shallow (150–200 MPa, corresponding to 6–8 km) felsic (trachyte‐phonolite) storage area, recharged by a mafic (trachybasalt‐shoshonite) deeper (>200 MPa) source. These reservoirs, identified by petrological data, possibly represent permanent long‐lived storage areas, still present today as indicated by geophysical studies (e.g., Costanzo and Nunziata, 2017; De Natale et al., 2006; Fedi et al., 2018; Zollo et al., 2008).…”
The Campi Flegrei caldera is considered the most dangerous volcano in Europe and is currently in a new phase of unrest (started in 2000 and still ongoing) that has persisted intermittently for several decades (main crisis occurred from 1950 to 1952, 1970–1972, and 1982–1984). Here, by combining the petrological and geochemical data collected in recent decades with numerical simulations, we place new constraints on the source(s) of the current dynamics of the volcano. In particular, we show that the measured (N2‐He‐CO2) geochemical changes at the fumaroles of Solfatara hydrothermal site are the result of massive (about 3 km3) magma degassing in the deep portion (≥200 MPa, 8 km of depth) of the plumbing system. This degassing mechanism would be able to flood the overlying hydrothermal system with hot gas, thus heating and fracturing the upper crust inducing shallow seismicity and deformation. This implies that the deep magma transfer process (≥8 km) has been decoupled from the source of deformation and seismicity, localized in the first kilometers (0–4 km) of caldera‐filling rocks. This information on magma transfer depth can have important implications for defining the best monitoring strategies and for forecasting a future eruption. Finally, this study highlights how petrological and geochemical data allow us to explore the dynamics of the deep portion of the plumbing system and thus trace the occurrence of recharge episodes, in a portion of the ductile lower crust where magma transfer occurs in the absence of earthquakes.
“…In this work, the geothermobarometers of Putirka [13] and Masotta et al [30] have been used to estimate pressures and temperatures of crystallization of olivine, clinopyroxene and feldspar crystals from volcanic products belonging to different periods of Campi Flegrei activity. In the last decades, various studies that used different geological, geochemical and/or geophysical information have tried to estimate the depths of magma storage below Campi Flegrei (e.g., [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]). Moreover, geothermometric estimates have been performed in several studies (e.g., [51][52][53][54][55][56][57][58]) in order to reconstruct the pre-eruptive temperature conditions of the magmas feeding different eruptions (e.g., Campanian Ignimbrite, Agnano-Monte Spina, Astroni).…”
The eruptions of Campi Flegrei (Southern Italy), one of the most studied and dangerous active volcanic areas of the world, are fed by mildly potassic alkaline magmas, from shoshonite to trachyte and phonotrachyte. Petrological investigations carried out in past decades on Campi Flegrei rocks provide crucial information for understanding differentiation processes in its magmatic system. However, the compositional features of rocks are a palimpsest of many processes acting over timescales of 100–104 years, including crystal entrapment from multiple reservoirs with different magmatic histories. In this work, olivine, clinopyroxene and feldspar crystals from volcanic rocks related to the entire period of Campi Flegrei’s volcanic activity are checked for equilibrium with combined and possibly more rigorous tests than those commonly used in previous works (e.g., Fe–Mg exchange between either olivine or clinopyroxene and melt), with the aim of obtaining more robust geothermobarometric estimations for the magmas these products represent. We applied several combinations of equilibrium tests and geothermometric and geobarometric methods to a suite of rocks and related minerals spanning the period from ~59 ka to 1538 A.D. and compared the obtained results with the inferred magma storage conditions estimated in previous works through different methods. This mineral-chemistry investigation suggests that two prevalent sets of T–P (temperature–pressure) conditions, here referred to as “magmatic environments”, characterized the magma storage over the entire period of Campi Flegrei activity investigated here. These magmatic environments are ascribable to either mafic or differentiated magmas, stationing in deep and shallow reservoirs, respectively, which interacted frequently, mostly during the last 12 ka of activity. In fact, open-system magmatic processes (mixing/mingling, crustal contamination, CO2 flushing) hypothesized to have occurred before several Campi Flegrei eruptions could have removed earlier-grown crystals from their equilibrium melts. Moreover, our new results indicate that, in the case of complex systems such as Campi Flegrei’s, in which different pre-eruptive processes can modify the equilibrium composition of the crystals, one single geothermobarometric method offers little chance to constrain the magma storage conditions. Conversely, combined methods yield more robust results in agreement with estimates obtained in previous independent studies based on both petrological and geophysical methods.
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