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A new geological map of Stromboli (southern Italy) at 1:10,000 scale is performed by adopting a modern stratigraphic approach based on lithostratigraphic units (rock types), lithosomes (landforms eruptive centres) and unconformity-bounded units (correlations). The eruptive, structural and magmatic history of Stromboli is described as a result of six major constructional stages (eruptive epochs) separated by periods of quiescence, erosion and volcano-tectonic collapses (calderas and lateral collapses). The epochs of activity are characterized by distinctive compositional features of the erupted products, ranging from the calc-alkaline to potassic, through high-K calcalkaline and shoshonitic series. Insights on hazard assessment are provided by stressing the role played by recurrent lateral collapses in controlling the location of eruptive vents and activity through time. A number of eccentric eruptive fissures are recognized along the NE and W flanks of Stromboli during the Holocene, together with a detailed mapping of the most recent lava flows from summit vents and fissures along Sciara del Fuoco and the distribution of the major paroxysmal spatter deposits. Moreover, a (chrono)stratigraphy of the Recent Stromboli units and information on the onset of the Present-day activity of Stromboli are provided.

New stratigraphic data allowed the reconstruction of the activity responsible of the construction of the Monte dei Porri cone. Alternating explosive and effusive activity, which emplaced fall and pyroclastic density current deposits, and lava flows, form the volcanic cone. The magma composition that fed the different phases of the Monte dei Porri eruptive cycle is poorly evolved to intermediate (basaltic, basaltic andesite and andesite), with the exception of that of the initial phase (dacitic). Hydromagmatic fragmentation cannot be claimed for explaining large variations in explosivity deduced from the stratigraphic succession, being excluded by SEM image analysis on coarse ash from the different pyroclastic units. This suggests that mechanisms responsible of eruption style transitions have to be searched in timing of magma rising, including variations in the local tectonic stress in combination with variable magma chamber overpressure.

Vulcano geological history displays several changes of eruption magnitude, eruption styles and composition of magmas through time. Various volcanic edifices and two intersecting multi-stage calderas resulted from such evolution. The collection for many years of detailed geological data on this island (as well as on those nearby) have made it possible to carry out a detailed lithostratigraphy together with the identification of lithosomes and unconformity-bounded units (UBU) based on the main volcano-tectonic events and/or shifting of volcanic centres. Together with the critical use of available radiometric ages and compositional data as well as the knowledge of regional tephrochronology, this has finally provided the ability to synthesize in a map - at 1:10,000 scale - a large number of information, ranging from the duration of the volcanic activity to the hazard(s) assessment on the island. In particular, this geological map includes a thematic map on volcanic hazard derived from an even more detailed stratigraphy and geological survey performed on La Fossa Cone, where the most recent volcanic activity occurred. The historical activity of this tuff cone is characterized by several eruptions, with the latest eruption occurred during 1888–1890 AD and representing the tail of a two millennia long period of activity. As it is deduced from its stratigraphic record, most of the eruptions were characterized by pulsatory explosive events mainly driven by phreatomagmatic processes, with a minor role for magmatic fragmentation. Both the fragmentation mechanisms involved compositionally distinct magmas (from shoshonites to rhyolites), often mutually interacting (mingling, mixing). They led to the formation of hundreds of meters thick, dilute and turbulent pyroclastic density currents (PDCs), of base surges type, formed in rapid succession and moving down the volcano slope at velocities exceeding 50 m/s. The dispersion of these PDCs affected the whole Vulcano Porto and Vulcanello areas and for one eruption (Grotta dei Palizzi 2 Formation, 1.6 ka) also overrode the La Fossa Caldera rims, spreading radially over further Vulcano areas. Fallout of ballistic blocks and bread-crust bombs on intermediate-distal area was limited. With the aim to provide for a possible reactivation of La Fossa cone, a short-term eruptive scenario (tens to hundreds of years) has been drawn. Going into detail, the PDCs related to the Grotta dei Palizzi 2 activity are expected to be the most hazardous events in future eruptions and the corresponding deposits are used as the best reference for this hazard scenario. In order to quantitatively express the expected impact of these density currents, the dynamic pressure and particle volumetric concentration were calculated. It’s important to stress that these parameters and the impact energy of ballistic blocks are derived through the physical stratigraphic study of volcanic products (definition of individual depositional units and their thickness, sedimentary structures, granulometry and clast morphology of the Grotta dei Palizzi 2 pyroclastics). In order to depict even a long-term eruptive scenario with similar physical parameters, also older deposits (the Upper Brown Tuffs) produced by recurrent hydromagmatic eruptions from the multiphase La Fossa Caldera were studied in detail.

Stromboli (southern Italy) is a 924 m-high active composite volcano made up of thick successions of scoriaceous products and lava flows subdivided by erosional discontinuities related to five calderas and seven large-scale lateral collapses (Francalanci et al. 2013). Volcanic hazards generated by the present-days intermittent and moderately explosive strombolian activity mostly consist of fallout of scoriae and ballistic blocks affecting the area around the summit craters, together with lava flows flowing down the Sciara del Fuoco collapse. These processes produce a limited hazard for the settled areas, which are only occasionally affected by the fallout of bombs and blocks during higher-energy explosions or paroxysms (at a decade-scale). Moreover, events of gravitational instability at various scales (both in time and volume) have occurred throughout the Stromboli history mostly along the north-western flank of Stromboli in the frame of the Sciara del Fuoco collapse, although minor SE-dipping collapse events are recognized to truncate the Pizzo cone on the summit of Stromboli in late Medieval times. The steep Sciara del Fuoco scar is the place where the historic to Present-day activities have mostly taken place, and is the result of recurrent NW-dipping collapses, at times associated with the development of landslides or debris avalanches giving rise to tsunamis events. A low-probability but remarkable hazard scenario is that a flank collapse triggers a large-scale hydromagmatic explosion (as a consequence of a sudden decompression of the magmatic-hydrothermal system) resulting in the generation of pyroclastic density currents (PDC) that flow down the slopes of the volcano (Bertagnini and Landi 1996; Giordano et al. 2008). Based on new geological and geochemical data, we provide the evidence for three distinct hydromagmatic eruptions occurred during the Holocene evolution of Stromboli at ~12.5 ka (Semaforo Nuovo), ~7 ka (Secche di Lazzaro) and ~4 ka (Semaforo Labronzo). As discussed in the literature, they are more likely related to successive collapse events of the Stromboli volcano. These eruptions have produced dilute PDCs able to reach the lower slopes of the volcano and deposit meters-thick pyroclastic accumulations in the surroundings of the settled areas of San Vincenzo-Stromboli (Semaforo Nuovo), Ginostra (Secche di Lazzaro) and Piscità (Semaforo Labronzo). According to these data, the occurrence of collapse-driven hydromagmatic eruptions and PDCs is an eruptive scenario more frequent than previously thought, thus introducing further (previously undervalued) source of volcanic hazard on Stromboli.

The Panarea volcanic group is made up of dome-fields that are the subaerial culminations of a largely dissected volcanic complex mostly located below sea level. The correlation of marine isotope stage (MIS) 5 marine terrace deposits and numerous tephra layers, combined with the available radiometric ages, shows that the Panarea dome-fields mostly developed between c. 155– 149 and 124–118 ka through the emplacement of successive lava domes, lava flows and minor pyroclastic products, interrupted by dormant periods and episodes of faulting in a context of regional uplift, plus volcano-related deformation. Recurrent explosive phases subsequently occurred in the area of minor islets at c. 100 ka (Punta Falcone), 67–56 ka (p1) and 24–8.7 ka (Drauto), together with the emission of the c. 54 ka Basiluzzo dome. The Panarea volcanic group is presently in a quiescent state with fumarolic activity and episodic gas outbursts. Panarea rocks show basaltic andesite and high-K basaltic andesite to high-K dacite and rhyolite compositions, with minor shoshonites. Radiogenic isotope signatures range between those typical of the western Aeolian islands and Stromboli. This reveals a heterogeneous mantle source, which resulted from migration of more primitive asthenospheric mantle from the west during slab rollback, and its admixture with more strongly contaminated Stromboli-type resident mantle

Stratigraphic, structural, volcanological and geochemical data allow a detailed reconstruction of the geological history of the island of Salina (central Aeolian sector). Its subaerial volcanism (~244 ka to 15.6 ka) developed through six successive Eruptive Epochs interrupted by major quiescence periods, volcano-tectonic collapses and recurrent episodes of marine terrace formation during MIS 7 and MIS 5. Several stratovolcanoes were constructed by strombolian and effusive (Pizzo Capo, Mt. Rivi, Mt. Fossa delle Felci, Mt. dei Porri) to hydromagmatic and subplinian (Mt. dei Porri, Pollara) activity, with a general east-to-west shift of active vents, controlled primarily by the dominant NNW-SSE and minor NE-SW regional tectonic trends, and a progressive chemical differentiation of the erupted products from calc-alkaline basalts to rhyolites. The magma compositions and variations through time are the result of contamination of primary magmas derived from a subduction-modified mantle source with the Calabro-Peloritano lower crust and subsequent differentiation dominated by polybaric fractional crystallisation. Magma mixing and mingling processes occurred during individual eruptions. The early basalts were fed from deep reservoirs located near the crust-mantle boundary, whereas the later andesitic to dacitic and, ultimately, rhyolitic magmas originated through combined assimilation and fractional crystallisation processes in magma reservoirs at mid- to upper-crustal levels.

A regional framework for stratigraphic correlations in the Aeolian archipelago is provided by widespread tephra layers and Late Quaternary marine terrace deposits combined with the available radiometric ages. Several tephra layers of Campanian and Aeolian provenance extending back to c. 110 ka are reported. The most important key-beds are the Ischia Tephra (56 ka), the Grey Porri Tuffs (70–67 ka) and Lower Pollara products (27.5 ka) from Salina, the M. Guardia pyroclastics from Lipari (27–24 ka) and the Brown Tuffs from Vulcano (c.70–8 ka). Late Quaternary marine terrace deposits are recognized along the coastal slopes of most of the Aeolian archipelago. They record distinct interglacial sea-level peaks during marine isotope stages (MIS) 5 and 7 in a context of prevalent long-term crustal uplift. Key erosional unconformities bounding the terrace deposits are the F1, UI, L3 and UII (in stratigraphic order). They are the ravinement surfaces formed at the onset of MIS 7.3 (F1), MIS 5e (UI) and MIS 5c interglacial peaks (L3), and the subaerial unconformity formed during the MIS 5a sea-level fall up to the emplacement of Brown Tuffs (UII). These unconformities are important regional-scale markers for chronostratigraphic classification and correlation between distant islands of the Aeolian archipelago.

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 shallowlevel reservoirs. Radiogenic isotope compositions are variable (87Sr/86Sr ¼ 0.70424–0.70587, 143Nd/144Nd ¼ 0.51254–0.51276, 206Pb/204Pb ¼ 19.305–19.759, 207Pb/204Pb ¼ 15.659–15.752, 208Pb/204Pb ¼ 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.

The geological history of Filicudi in the Middle–Late Pleistocene (246–29 ka) is described by four successive Epochs of activity separated by quiescence stages, erosional episodes during marine isotope stage (MIS) 7 and MIS 5 and the Vallechiesa sector collapse. The partially overlapping Casa Ficarisi, Fossa Felci and Chiumento stratocones and the Monte Guardia scoria cone are built up under control of the WNW–ESE regional tectonic trend, with a subsequent progressive south-eastwards shift and chemical differentiation towards the Monte Terrione and Capo Graziano domes. The Monte Montagnola dome (64 ka) and Case dello Zucco Grande pyroclastics (,56 ka) are the youngest products, together with the Canna neck (29 ka) of an independent volcanic centre offshore of Filicudi. Filicudi rocks are calc-alkaline basalts, basaltic andesites and high-K andesites with minor dacites. Incompatible elements increase from basalts to dacites, with much scatter. Sr, Nd and Pb isotopes show moderate variations. d18O‰of clinopyroxene phenocrysts ranges from þ5.37 to þ6.20, and shows the highest values in the mafic rocks. Geochemical data suggest a complex interplay of different evolution processes (fractional crystallization, crustal assimilation and mixing) for the various eruptive centres of Filicudi. Variable incompatible element ratios of mafic rocks are suggested to reflect source heterogeneity.

The Alicudi composite volcano (western Aeolian archipelago) was constructed between c. 106 and 28 ka by lava flows, domes and strombolian scoriae erupted during six Eruptive Epochs, interrupted by periods of dormancy and three caldera-type collapses in the summit area. Marine Isotope Stage (MIS) 5a (81 ka) terrace deposits and widespread Brown Tuffs of external origin are recognized and provide important marker beds for regional stratigraphic correlations. Volcanism was of central type, under control of the summit caldera collapses with negligible influence of regional tectonic trends. Alicudi rocks are basaltic to high-K andesitic and have the most primitive petrological compositions (high MgO, Ni, Cr contents), the lowest Sr–O and the highest Nd–He isotope ratios (87Sr/86Sr ¼ 0.70352 to 0.70410; 143Nd/144Nd ¼ 0.51289 to 0.51279; d18O ¼ þ5.0 to 5.6; 3He/4He–R/Ra ¼ c. 6.5 to 7.1) over the entire Aeolian archipelago. Their composition and variation through time are the result of polybaric crystal–liquid fractionation of parental calc-alkaline basalts to give basaltic andesitic and andesitic derivative melts. These underwent crustal assimilation during ascent, with basalts being contaminated more strongly than andesitic magmas. Sr–Nd–Pb isotopes suggest source metasomatic modification by fluids from an oceanic-type slab, with a minor role for subducted sediments.

Introduction to the Memoir no 37 of the Geological Society of London dedicated to the geology, eruptive history and magmatology of the Aeolian Islands (including a CD-ROM with 1:10000 scale maps and three mathy-morphological maps of the submarine portions)

The geological map at 1:50.000 scale of the El Tatio volcanic area (central Andes, northern Chile) is presented. The map is performed on the basis of i) geological field survey, ii) satellite-aerial imagery analysis, iii) petrochemical investigation and iiii) literature radiometric ages. Using reconstructed unconformity-bounded stratigraphy, together with more descriptive lithostratigraphic units and lithosomes, the Miocene Quaternary geological history of the study area is described in terms of the interaction between volcanic activity of local and external provenance, and regional fault systems. Local andesitic to dacitic lava cones, stratovolcanoes and monogenic lava domes are emplaced mostly during the Pleistocene (and subordinately during the Miocene) under control of NE-SW to N-S alignments. Local volcanic products are interbedded with regional ignimbrite sheets originated in the Altiplano Puna Volcanic Complex from Miocene to Pleistocene. Periods of volcanic inactivity during the Pleistocene are characterized by extensional tectonic phases developing along NW-SE-aligned normal faults. The youngest tectonic event during middle-late Pleistocene is demonstrated by a series of roughly NNE-SSW trending, west-verging thrust faults, which, in addition to a local NW-SE-oriented strike-slip lineament, indicate contractional deformation processes in a NW-SE direction. The easternmost thrust fault is proposed to have driven magma ascent leading to the emplacement of the 34-ka-old Co. La Torta rhyolitic lava dome, which is the youngest recorded phase of activity in the study area. Field evidence of glacial advance during the Last Glacial Maximum (and, subordinately, during middle-late Pleistocene major glaciations) is recorded in the entire study area providing a relative age assignment of most of volcanic products and tectonic features. At present, the study area is characterized by intense fluid discharge in the El Tatio geothermal field, which is apparently conditioned by the westermost portion of the demonstrated thrust fault system.

We report new petrographic and geochemical data on volcanic rocks emplaced fromMiocene to late Peistocene in El Tatio volcanic region (Central Volcanic Zone, Andes). They originated from dominantly effusive volcanism and minor low-mild explosive eruptions, giving rise to several stratovolcanoes and lava domes belonging to the Western Cordillera volcanic chain, in alternance with intense ignimbrite-type explosive activity from external caldera systems in the Altiplano Puna Volcanic Complex. El Tatio volcanics are mostly erupted in the last 1 Ma and display compositions ranging from calcalkaline (CA) to high-K calcalkaline (HKCA) basaltic andesite to rhyolite, with prevalence of andesites and dacites, which bear a tipycal subdution-related signature. Petrographic features of studied De Astis et al. 2 rocks - deeply resorbed and rounded mineral phases, reaction rims, skeletal habits, large ranges of mineral compositions with direct and reverse zoning, oxidations and uralitizations phenomena - are generally related to strong disequilibrium conditions in the crystallizing system. Based on our data, these disequilibrium features are better explained by convective self-mixing processes in magma reservoirs cooling from above and heated by mafic magma batch at camera bottom, rather than by magma mixing between compositionally different magmas. The high crystallization degree of rocks, together with evidence provided by geochemical data, suggests that fractional crystallization (FC) of recurrent mineral assemblages (plag.±pyrox±hornbl±bt) is the most significant differentiation process for several magmas from El Tatio suites. In addition, AFC (Assimilation plus FC) is another important evolutionary mechanism able to explain some trends correlating the few available isotopic data and some geochemical indexes. Isotopic trends and patterns of incompatible elements (i.e., LILE enrichment, LILE/HFSE ratios) mirror the addition, via subduction, of different amounts of crustal material. Magma modification can occur either in the mantle wedge (fluids and melts from the slab) or during the ascent/ponding of parental magmas within the thick crust of Central Andes. Finally, we suggest that the high level magma reservoirs hosting magmas of El Tatio region are characterized by multistage evolutionary processes consistent both with open- and closed-system regimes.

Pure CO2 fluid inclusions are observed in fifteen quartz-rich xenoliths collected in basaltic-andesitic to andesitic volcanic products relevant to the older evolutionary stages of Lipari Island (223-105 ka). In volcanics forming central composite volcanoes (M. Mazzacaruso, 223-127 ka; and M. S.Angelo, 105 ka), fluid inclusions are trapped during two distinct events: early Type I inclusions formed before host magma transport, and late (i.e. secondary) Type II inclusions trapped during magma ascent. Early Type I inclusions show homogenization temperatures corresponding to densities from 0.9 to 0.6 g/cm³, while Type II inclusions record a considerably lower density interval between 0.38 and 0.1 g/cm³. At the estimated trapping temperatures between 950 and 1090°C, obtained density values correspond to pressures of 0.58-0.25 GPa (22-16 km) for Type I, and 0.13-0.03 GPa (5.5-1 km) for Type II inclusions, respectively. In those magmas erupted from fissural eruptive vents aligned along the main regional NNW-SSE and E-W faults systems (Timpone Ospedale, Monterosa and M.Chirica; 223-127 ka) only early Type I inclusions are observed. Density values form to two distinct intervals between 0.8 and 0.6 g/cm3 (M. Chirica), and between 0.68-0.18 g/cm³ (0.32-0.05 GPa; 12-2 km; Timpone Ospedale and Monterosa). Fluid inclusion data together with tectonic features outline a complex magma storage and ascent evolution during the Lipari’s older evolutionary stages. Beneath the central volcanoes of M. Mazzacaruso, M. S.Angelo and the M. Chirica, two magma reservoirs, located at lower crustal depths (~22 km; close to the Moho) and at very shallow levels (5.5-1 km), are present. Mantle-derived magmas are accumulated into the deep magma chamber and may then reside in the shallower reservoir for a short period of time before being erupted to the surface. Such a magma feeding system is similar to those outlined for the Alicudi and Stromboli volcanoes, and for most of the Vulcano’s eruptive stages. Conversely, an intermediate magma reservoir at middle crustal levels (~12 km) is shown to play an important role in storage and differentiation processes of mafic magmas relevant to the fissural eruptive vents of Timpone Ospedale, Monterosa, and M. Chirica. Magmas more likely arise from the deepest magma storage level located close to the Moho, as outlined by M. Chirica eruptive vent. The proposed scenario is that the regional fault systems control the magma storage evolution, contributing to create a zone of preferential accumulation at mid- crustal levels. Fault systems may also influence magma ascent and determine the upward magma movement directly to the eruptive system without an effective ponding in the shallow reservoirs located at 5-1 km depth. At mid-crustal depths, magmas may reside for long time, and low rates of fractional crystallization occur. The occurrence of an intermediate storage level at similar depths beneath the rhyolitic Lentia domes at Vulcano, which are aligned along the main NNW-SSE tectonic trend, supports present model.

breve sintesi delle peculiarità vulcanologiche e naturalistiche dell'arcipelago Eoliano

The Unconformity-bounded units are employed for the reconstruction of the geological evolution of the Ustica Island as the result of the interaction between volcanic activity, tectonics, and sea-level fluctuations. The Ustica Island is located in the Southern Tyrrhenian sea in the eastern sector of the Sicilian-Maghrebian Chain. It mainly consists of volcanic products, basaltic to trachitic in composition and belonging to a sodic-alkaline series and, subordinately, of marine deposits (conglomerates, sands and fossiliferous sediments) belonging to a well-preserved series of terraces intercalated within the volcanic succession. Seven successive raised paleo-shorelines are recognized at elevation ranging from 115 m to 8 m a.s.l and are attributed to major sea-level highstand peaks by means of stratigraphic relationships with dated volcanic products, relative dating of fossils and relative chronostratigraphic attribution: paleoshoreline I is attributed to marine oxygen-isotope stage (MIS) 13, paleoshoreline II and III to distinct peaks during MIS 9, paleoshorelines IV, V and VI to MIS 7, paleoshoreline VII order (a, b, c) to MIS 5. Following modern stratigraphic procedures to stratigraphic analysis in volcanic areas, marine deposits are adopted as a powerful means of correlation by adopting the unconformity-bounded concept. They are interpreted as transgressive deposits formed during main sea-level highstands and are bounded by sub-horizontal unconformities: the basal unconformity is the marine erosion surface formed during the sea-level raising, whereas the top unconformity is the surface of subaerial exposure and erosion developed during the following sea-level lowering. In addition, several unconformities formed in relation to endogenous processes of modification of the volcano (quiescence periods, shifting of eruptive centres, ecc.) are introduced at Ustica and hierarchized according to their areal extendibility. First-order unconformities UI and UII bounding MIS 5 marine deposits have a potential regional stratigraphic significance and are documented at Ustica after their first definition across the Aeolian archipelago. Then, five second-order (and one third-order) unconformities with stratigraphic significance for the whole Ustica Island are introduced. The resulting unconformity-bounded stratigraphy allows reconstruction of the geological evolution of Ustica as the result of four successive constructive, relatively short-lived stages of volcanic activity (eruptive epochs), which are separated by longer inter-eruption periods of quiescence when erosion and mass-wasting processes in subaerial and marine environments become prevailing. Most ancient volcanic products dated at more than 750 ka are represented by subaerial pyroclastic deposits emplaced from dilute pyroclastic density currents coming from an eruptive centre located SWwards offshore the Ustica Island. Then, the second and third eruptive epochs document the progressive transition from submarine volcanism (hyaloclastites and pillow lavas) to subaerial eruptive activity with the emplacement of lava products, and of pyroclastic deposits from both dilute and concentrated pyroclastic density currents originated from eruptive centres located in the central sector of Ustica. The fourth and most recent volcanic activity, between 200 and 124 ka, determines the construction of the eccentric Falconiera tuff cone, located in the NE portion of the island. The Ustica Island is inactive during the last 124 ka, and is charaterized by diffuse and recurrent subaerial erosion and reworking.

guida vulcanologica e naturalistica delle Isole Eolie

In the meanframe of the “EDU-GEO” Project sponsored by FIST, we propose a prototype of a geological field excursion across the active Vulcano island (Aeolian archipelago) which provides a 130 ka old outstanding record of building and destruction processes in volcanic terranes and of ongoing volcanic phenomena. Studied since at least the 18th century, the Vulcano Island is the paradigm of the Vulcanian type of eruptions and has featured significantly in the vulcanological literature for more than 200 years, still continuing to provide a fundamental field for volcanological studies of on-going development of landforms. The excursion is focused on mature high-school students (17-19 years old) and on their teachers by means of an appropriate educational strategy based on high scientific content. We believe that Vulcano is an excellent field example for introducing Volcanology to students because it addresses all main criteria in the geosites definition suggested by European ProGeo that is: 1) representativeness; 2) scientific interest; 3) rarity; 4) landscape importance; 5) educational value; 6) accessibility; 7) conservation standing; 8) vulnerability. The whole excursion is performed on the field because landforms and deposits are perfectly exposed at Vulcano, whereas introductory concepts are provided through the Internet by guidelines for teachers and lecture notes for students. We aim at improving students knowledge of rocks and landforms as tools for studying a volcanic area through a typical scientific approach based on the objective observation of field data and their consequent interpretation. So, independent observation and interpretation by the students are always stimulated by means of cause-effect examples and of comparison with other reknown examples. The following main geological aspects of a volcanic area are addressed at Vulcano: 1) building and destruction of a volcano; 2) origin and emplacement mechanisms of volcanic deposits; 3) criteria for the evaluation of volcanic hazard and risk. The first part of the excursion is focused on the fundamental stages of birth and evolution of the Vulcano island by means of an easily accessible (even for disable people) route from the harbour of Vulcano to the base of the La Fossa cone. The route consists of a few stops which are especially meaningful for the high degree of exposure of landforms aimed at showing a logically set out sequence of geological events from the progressive emergence of the volcanic island (e.g. the 2000 years old Vulcanello peninsula) to its subaerial stabilization (e.g. the 6000 years old and still active La Fossa cone). Traces of main caldera collapses displacing the volcanic apparatus are shown so to highlight the role of destructive events in the evolution of a volcano. The second part of the excursion is developed across the footpath that goes to the summit crater of La Fossa. There, detailed observation of lavic and pyroclastic deposits is possible and the connection to the corresponding source of provenance and emplacement mechanisms (effusive activity, fallout processes, pyroclastic density currents) is explained. Finally, the last part of the excursion is performed across the summit crater of the La Fossa cone with the purpose of showing main procedures of geochemical monitoring (e.g. the crateric high-T gas fumaroles) and evaluation of volcanic hazard from pyroclastic currents.

The Aeolian Volcanic District is a geologically complex region characterised by a wide spectrum of volcanism and compositionally variable magmatism younger than 1-1.3 Ma. Submarine and subaerial volcanic activities formed seven large strato-volcanoes, that upraise from ~1500-2000 m b.s.l., and several seamounts. The Aeolian volcanism is the result of the long interplaying among collision, subduction and extension processes occurred in the Mediterranean area affected by multiple geodynamic processes. Geophysical, seismological and geochemical data allow recognition of three main sectors, each characterized by remarkably similar structural, volcanological and compositional features. The eastern sector (including Stromboli-Panarea) is characterised by a prevailing nne-ssw to ne-sw striking fault system, deep seismicity and magmas with variable affinity, from CA to KS, generally outpured through low-intensity eruptions. The central sector (including Lipari, Vulcano and the younger part of Salina) is strongly affected by the presence of the nnw-sse oriented strike-slip lithospheric fault system known as ‘Tindari-Letojanni’. Eruptive activity in the central sector shows the wider spectrum of magma compositions in the archipelago – ranging from basalts to rhyolites, with CA, HKCA, SHO and KS affinity – and the eruptions with the highest intensity and magnitude. The western sector (including the older part of Salina, Filicudi and Alicudi) is characterized by a main wnw-ese striking fault system that conditioned the development of both subaerial and submarine volcanoes, basically characterized by CA to HKCA mafic and intermediate magmas of subduction origin. Going from east to west, a general increase of crust thickness (from ~17 km below Stromboli up to ~25 km below the western sector) and magma composition variations (with a general decrease of Sr-isotopes and an increase of Nd-, Pb-isotope and LILE/HFSE ratios) are observed. Overall, trace elements and radiogenic isotopes signatures variations along the avd indicate modifications in the nature and intensity of metasomatic processes occurred in the Aeolian mantle. The eruptive history of each island is reconstructed by giving special emphasis to the chronostratigraphic role played by fossil marine conglomerates intercalated to volcanic products. Older and more primitive CA basalt to basalt-andesite volcanic products related to strombolian and effusive volcanic activity were emplaced on Salina and Filicudi in a poorly constrained time span started around 430-400 ka. After an apparently long period of quiescence, volcanic activity started again between ~220 and 124 ka on Filicudi, Salina, Lipari and Panarea, with the emplacement of CA basalt-andesite to andesite and dacite volcanics related to mainly strombolian and effusive activity, with a minor role for explosive hydromagmatic eruptions. Between ~124 and 80 ka, HKCA andesitic and subordinate dacitic volcanic products related to both explosive (mainly hydromagmatic) and effusive volcanic activity were emplaced on Lipari, and Alicudi, whereas on Vulcano and Stromboli SHO products were erupted together with minor HKCA lavas. Starting from ~80 ka, more evolved CA and HKCA andesitic to daci-trachytic -up to rhyolitic products were mainly erupted on Lipari and Salina and to a lesser extent on Panarea, Alicudi and Filicudi. Most of these magmas were produced by effusive activity (mainly dome-forming) and associated high-energy explosive eruptions. In the last 25 ka ca., a growing and intensification of the volcanism in the central sector – probably associated to increased activity of the Tindari-Letojanni fault system – occurred; whereas volcanism ceased in the western sector and was regular and almost continuous in the eastern one through Stromboli. At present time Vulcano, Stromboli and submarine area of Panarea show active volcanic phoenomena.

The area of El Tatio (Chile), in the central sector of Andean Cordillera, is known since long time owing to the presence of a large geothermal field and to its location at the center of one of the widest Neogene ignimbrite provinces on Earth. Since the late Cretaceous and in particular starting from the late Miocene (about 10.4 Ma), intense and repeated episodes of silicic volcanism gave rise to a volcanic province, the Altiplano-Puna Volcanic Complex, between latitudes 21°-24° S in the Central Volcanic Zone. New stratigraphic studies of the El Tatio area have highlighted the occurrence of significant unconformities in the frame of the volcanic activity developing in the time span between Cretaceous and Holocene. Those unconformities allow volcanic history to be subdivided in four main eruptive epochs: • the late Cretaceous eruptive epoch is characterized by volcanic activity, probably occurring in a backarc geodynamic setting, which is documented by scarce outcrops in the northwesternmost sector of the studied area, of pyroclastics and lavas intercalated within the top portion of the underlying sedimentary succession; • in the upper Miocene-Pliocene, volcanic activity is mostly explosive and determines the emplacement of great volumes of ignimbrites (Rio Salado, Sifon and Puripicar and to the intrusion of the Copacoya subvulcanic body; • the Pleistocene eruptive epoch is characterized by the intensemost volcanic events which determine the emplacement of several volcanic edifices (the main ones are Quebrada Chucula, Tatio and Deslinde-Tatio) through mainly effusive volcanic activity. Those volcanic edifices are N-S and NNE-SSW-aligned (in the easternmost sector) following the main tectonic lineament developing on a regional scale which borders the margin of the Altiplano-Puna representing a segment of the Western or Main Range of the chilean Ande. During the Pleistocene eruptive epoch, an important explosive event also occurs determining the emplacement of widespread ignimbrites (Tatio ignimbrite) in the whole central and eastern sectors of the studied area; • finally, the recentmost Holocene eruptive epoch is characterized by the building of the Tocorpuri volcanic edifice which is located in the southeasternmost sector of the studied area. As regards tectonics, four thrust surfaces offset the above described volcanic successions and the volcanic edifices, probably extending in depth and cutting the volcanic conduits. Thrust surfaces strike in a grossly N-S direction and dip to the east. The direction of tectonic transport (vergence) is toward the west, as suggested by thrust geometry, displacement of the volcanic bodies and mesostructural analyses. Another structural lineament of regional importance is a system of en-echelon sinistal strike-slip faults, extending from southest to northwest and offsetting the thrust planes (Cizalla del Tatio fault). Notably, the displacement of thrust surfaces due to the strike-slip fault system decreases from west to east. This may suggests that the Cizalla del Tatio fault has been active together with the thrust faults, and the onset of the westernmost thrust planes, such as the Cablor and Cablor superior thrusts, should be older than the esternmost (Tocorpuri thrust). The different age of nucleation of thrusts is also suggested by the different ages of the displaced volcanic stratigraphic units. Moreover, the Cizalla del Tatio fault plays an important role in the hydrothermal activity of the well-known El Tatio geothermic field. The petrochemical study of volcanics from the El Tatio area puts in evidence the occurrence of prevailing dacites and subordinate andesites and rhyolites related to calcalkaline and HK-calcalkaline associations. Despite the limited range of shown compositions, the occurrence of strong differentiation allowed evolutive patterns to be evaluated.

The goal of this paper is to describe a modern approach to the geological cartography in volcanic settings based on an integrated use of UBSU, lithosomatic and lithostratigraphic units.

Over the last ~267 ky, the island of Lipari has erupted magmas ranging in compositions from basaltic andesites to rhyolites, with a notable compositional gap in the dacite field. Bulk geochemical and isotopic compositions of the volcanic succession, in conjunction with major and trace elemental compositions of minerals, indicate that the rhyolites were dominantly generated via crystal fractionation processes, with subordinate assimilation. Radiogenic (Sr, Nd, and Pb) and stable (O) isotopes independently suggest ≤30 % of crustal contamination with the majority of it occurring in mafic compositions, likely relatively deep in the system. Within the rhyolites, crystal-rich, K2O-rich enclaves are common. In contrast to previous interpretations, we suggest that these enclaves represent partial melting, remobilization and eruption of cumulate fragments left-over from rhyolite melt extraction. Cumulate melting and remobilization is supported by the presence of (1) resorbed, low-temperature minerals (biotite and sanidine), providing the potassic signature to these clasts, (2) reacted Fo-rich olivine, marking the presence of mafic recharge, (3) An38–21 plagioclase, filling the gap in feldspar composition between the andesites and the rhyolites and (4) strong enrichment in Sr and Ba in plagioclase and sanidine, suggesting crystallization from a locally enriched melt. Based on Sr-melt partitioning, the high-Sr plagioclase would require ~2300 ppm Sr in the melt, a value far in excess of Sr contents in Lipari and Vulcano magmas (50–1532 ppm) but consistent with melting of a feldspar-rich cumulate. Due to the presence of similar crystal-rich enclaves within the rhyolites from Vulcano, we propose that the eruption of remobilized cumulates associated with high-SiO2 rhyolites may be a common process at the Aeolian volcanoes, as already attested for a variety of volcanic systems around the world., Contributions to Mineralogy and Petrology, 170 (5-6), ISSN:0010-7999, ISSN:1432-0967