The monzogabbroic intrusion in the island of Vulcano, Aeolian Archipelago, Italy

Faraone, Domenico; Silvano, A.; Verdiani, Giorgio

doi:10.1007/bf01081758

Cited by 50 publications

(22 citation statements)

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“…The lack of magnetic properties in a large area beneath the western part of the caldera, deduced from the magnetic modelling, could be interpreted as a result of hydrothermal alteration that occurred in the past, suggesting that the hydrothermal system is now less developed. In fact, the drillings show that temperature at 1 km reaches a value of approximately 100°C (Faraone et al 1986), and this means that the demagnetization of the structures pertaining to the volcanic edifice cannot be simply explained as a consequence of present thermal anomalies.…”

Section: Subsurface Structure Beneath the Fossa Calderamentioning

confidence: 98%

“…This well encountered rapidly increasing temperatures from approximately 1,140 m (112°C) to the bottom at 2,050 m, where the temperature exceeded 419°C. A second well was drilled, which deviated towards north and reached a vertical depth of 1,578 m, with a lateral shifting of 458 m. This hole found a temperature of 243°C at 1,338 m and between 350 and 400°C at the bottom (Faraone et al 1986). …”

Section: Structural Features and Volcanic Evolution Of Vulcanomentioning

confidence: 98%

“…Drilling carried out by the Italian National Petroleum Company AGIP for geothermal purposes provided very valuable information on the subsurface structure beneath the Fossa caldera (Faraone et al 1986). The two boreholes drilled inside the caldera (Fig.…”

Section: Structural Features and Volcanic Evolution Of Vulcanomentioning

confidence: 99%

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Imaging and modelling the subsurface structure of volcanic calderas with high-resolution aeromagnetic data at Vulcano (Aeolian Islands, Italy)

2006

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In this paper, we present a magnetic model of the subsurface structure of Vulcano island based on highresolution aeromagnetic data. Three profiles across the most intense magnetic anomalies over the Piano and Fossa calderas were selected for the magnetic modelling, which was constrained by structural and volcanological data, previous geophysical models, paleomagnetic data, and borehole stratigraphy obtained from two deep wells. The interpretation of the magnetic sources represents a significant contribution to the understanding of the Piano and Fossa calderas' underlying structure, providing us with evidence of the lateral discontinuity between them at depth. We propose that the positive magnetic anomalies in the Piano caldera area are caused by: (a) the remnants of an early submarine volcano; (b) an outcropping dyke swarm related to the feeding system of the Primordial Vulcano phase (beneath Mt. Saraceno); and (c) the presence of a non-outcropping dyke system intruded along a NE-SWoriented intra-caldera fault (beneath the eastern part of the Piano caldera). Offshore, to the west, the magnetic anomaly map suggests the presence of a submarine volcanic structure, not revealed by bathymetric data, which could represent the eruptive centre, the presence of which has been indirectly deduced from the outcrop of eastern-dipping lavas on the western seashore. Magnetic modelling of the Fossa caldera points to the presence of a highly magnetized cone-like body inside the Fossa cone, centred beneath the oldest crater rims. We interpret this body as a pile of tephritic lavas emplaced in an early phase of activity of the Fossa cone, suggesting that the volume of mafic lavas that erupted at the beginning of the construction of the Fossa edifice was more significant than has previously been deduced. Furthermore, the presence of a magnetized body inside the Fossa cone implies that high temperatures are contained in very limited spaces, do not affect its bulk inner structure, and are restricted to fumarolic conduits and vents. In addition, structures beneath the western and northern part of the Fossa caldera are revealed to have null or low magnetization, which can be ascribed to the presence of pyroclasts and hyaloclastites in this area as well as to a large volume of hydrothermally altered materials. This suggests that the hydrothermal system, with a very limited extension at present, affected a larger area in the past, especially beneath the western part of the caldera.

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Section: Subsurface Structure Beneath the Fossa Calderamentioning

confidence: 98%

Section: Structural Features and Volcanic Evolution Of Vulcanomentioning

confidence: 98%

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Imaging and modelling the subsurface structure of volcanic calderas with high-resolution aeromagnetic data at Vulcano (Aeolian Islands, Italy)

2006

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“…The southern-most borehole encountered a shallow monzodioritic intrusion at c. 1350 m b.s.l. (Faraone et al 1986). Overall, the interpretation of the subsurface sequences above the collapsed volcanic products would suggest the presence of both lavas and minor hyaloclastites, hundreds of metres thick.…”

Section: Site and Structural Settingmentioning

confidence: 99%

Chapter 11 Geology, volcanic history and petrology of Vulcano (central Aeolian archipelago)

Astis

Lucchi

Dellino

et al. 2013

Memoirs

108

183

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Vulcano is an active NW–SE-elongated composite volcano located in the central Aeolian archipelago. Based on available radiometric ages and tephrochronology, the exposed volcanism started at c. 127 ka and spread through eight Eruptive Epochs separated by volcano-tectonic events and major quiescent stages. Various eruptive centres and two intersecting multi-stage calderas resulted from such evolution. Vulcano geological history displays several changes of eruption magnitude, eruption styles and composition of magmas through time. Vulcano rocks range from basalt to rhyolite and show variable alkali contents, roughly increasing during time. Magmas with low to intermediate SiO2 contents and high-K to shoshonite affinity prevail in the early Epochs 1–5 (c. 127–28 ka), whereas intermediate to high-SiO2 shoshonite and potassic alkaline products dominate the last three Epochs (<30 ka). This sharp increase in silicic products is related to the shallowing of the plumbing system and resulting major role of the differentiation processes in shallow-level reservoirs. Radiogenic isotope compositions are variable (87Sr/86Sr=0.70424–0.70587, 143Nd/144Nd=0.51254–0.51276, 206Pb/204Pb=19.305–19.759, 207Pb/204Pb=15.659–15.752, 208Pb/204Pb=39.208–39.559) as a result of both source heterogeneities and shallow-level interaction of magmas with continental crust. The compositional variations of mafic magmatism with time suggest that the source zone changed from a metasomatized, fertile, ocean island basalt- (OIB-) like mantle to a metasomatized depleted lithospheric mantle.DVD:The 10 000 scale geological map of Vulcano is included on the DVD in the printed book and can also be accessed online at http://www.geolsoc.org.uk/Memoir37-electronic. Also included is a full geochemical data set for Vulcano.

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“…The La Fossa crater of Vulcano is theoretically a favourable environment for the observation of volcanomagnetic phenomena, since the subsurface structure includes (1) a large shallow aquifer (Cioni & D’Amore 1984), (2) an intrusive body (Ferrucci et al 1991) composed of high‐susceptibility rocks (Barberi et al 1994), and (3) displays evidence of very high temperatures (420 °C) at depths of less than 2 km (Faraone et al 1986). Up to now, geophysical evidence for the existence of a magma chamber has not been recognized in seismic (Ferrucci et al 1991), gravity (Budetta et al 1983; Faraone et al 1986) or magnetic (Barberi et al 1994) data. However, the extremely evolved nature of Vulcanian magmas (De Astis et al 1997) requires a shallow storage level, allowing for the final in situ evolution of intermediate magmas of deeper origin (mostly andesitic).…”

Section: Magnetic Transients Expected At Vulcanomentioning

confidence: 99%

Volcanomagnetic effects at Vulcano Island (Aeolian archipelago, Italy)

Negro¹,

Ferrucci

2000

Geophys. J. Int.

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The installation of two continuously operating proton magnetometers, 2 km apart and sampling simultaneously every 5 min, on Vulcano Island from 1990 November to 1991 December allowed the detection of some transient anomalies thought to result from internal variations in the physical state of the volcano. The difference of mean values in the magnetic field at the two stations underwent a slow variation of 2 nT during the period of measurements. The mean values in the total intensity at one station were inversely correlated to the difference between the mean values of the two stations. This suggests that the contribution to the signal generated by the transitory magnetic field may be broken down into two parts: one of external origin, which is identical for both stations, and another of internal origin, proportional to the former, but dependent on the site. Following on from this simple description of the magnetic field, a method of analysis was developed to distinguish between transients of volcanomagnetic origin and transients generated by strong variations in the external transitory magnetic field. An accurate analysis, which takes into account the correlation between the measurements at the two stations, leads to the singling out of three magnetic anomalies (on 1991 April 2, July 18 and December 23). Comparison of the experimental data with the list of earthquakes occurring at Vulcano during 1991 showed the close temporal correspondence between the magnetic anomalies and earthquakes. The amplitude (between 2 and 4 nT), spatial extent (approximately 2 km) and polarity of anomalies point to the piezomagnetic effect as the primary physical mechanism driving these transient changes. On the other hand, the anomaly with respect to the regional field, observed over one year, is explicable in terms of a thermomagnetic effect detected at both stations. The magnetic static anomaly produced by a completely demagnetized spherical source, of 250 m radius located under the La Fossa crater at a depth of 1300 m, is in agreement with the slow changes observed at Vulcano.

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The monzogabbroic intrusion in the island of Vulcano, Aeolian Archipelago, Italy

Cited by 50 publications

References 2 publications

Imaging and modelling the subsurface structure of volcanic calderas with high-resolution aeromagnetic data at Vulcano (Aeolian Islands, Italy)

Imaging and modelling the subsurface structure of volcanic calderas with high-resolution aeromagnetic data at Vulcano (Aeolian Islands, Italy)

Chapter 11 Geology, volcanic history and petrology of Vulcano (central Aeolian archipelago)

Volcanomagnetic effects at Vulcano Island (Aeolian archipelago, Italy)

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