P42_copertina_R_OK C August 20-28,2004 Florence -Italy Field Trip Guide Book - P42 Post-Congress P.L. Rossi,C.A.Tranne L. Francalanci,F. Lucchi,M.Rosi, Associate Leaders:N.Calanchi,P.F. Dellino, Leader: R.DeRosa VULCANO (AEOLIANISLANDS) OF STROMBOLI,LIPARI, AND GEOLOGY ANDVOLCANISM 32 Volume n°5-fromP37toP54 GEOLOGICAL CONGRESS nd INTERNATIONAL P42 26-05-2004, 15:00:25 The scientific content of this guide is under the total responsibility of the Authors

Published by: APAT – Italian Agency for the Environmental Protection and Technical Services - Via Vitaliano Brancati, 48 - 00144 Roma - Italy

Series Editors: Luca Guerrieri, Irene Rischia and Leonello Serva (APAT, Roma)

English Desk-copy Editors: Paul Mazza (Università di Firenze), Jessica Ann Thonn (Università di Firenze), Nathalie Marléne Adams (Università di Firenze), Miriam Friedman (Università di Firenze), Kate Eadie (Freelance indipendent professional)

Field Trip Committee: Leonello Serva (APAT, Roma), Alessandro Michetti (Università dell’Insubria, Como), Giulio Pavia (Università di Torino), Raffaele Pignone (Servizio Geologico Regione Emilia-Romagna, Bologna) and Riccardo Polino (CNR, Torino)

Acknowledgments: The 32nd IGC Organizing Committee is grateful to Roberto Pompili and Elisa Brustia (APAT, Roma) for their collaboration in editing.

Graphic project: Full snc - Firenze

Layout and press: Lito Terrazzi srl - Firenze

P42_copertina_R_OK D 26-05-2004, 14:59:11 Volume n° 5 - from P37 to P54

32nd INTERNATIONAL GEOLOGICAL CONGRESS

GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS)

AUTHORS: R. De Rosa1, N. Calanchi2, P.F. Dellino3, L. Francalanci4, F. Lucchi2, M. Rosi5, P.L. Rossi2, C.A. Tranne2

1Università della Calabria, Dipartimento di Scienze della Terra, Arcavacata di Rende, Cosenza - Italy 2Università di Bologna, Dipartimento di Scienze della Terra e Geologico-Ambientali, S. Donato, Bologna - Italy 3Università di Bari, Dipartimento geomineralogico, Bari - Italy 4Università di Firenze, Dipartimento di Scienze della Terra, Firenze - Italy 5Università di Pisa, Dipartimento di Scienze della Terra, Pisa - Italy

Florence - Italy August 20-28, 2004

Post-Congress P42

P42_R_OK A 26-05-2004, 15:03:26 Front Cover: A panoramic view of North Vulcano as seen from the Island of Lipari

P42_R_OK B 26-05-2004, 15:03:28 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

Leader: R. De Rosa Associate Leaders: N. Calanchi, P.F. Dellino, L. Francalanci, F. Lucchi, M. Rosi, P.L. Rossi, C.A. Tranne

Introduction The Aeolian island arc represents a unique geological area, very well known all around the world as the site of some unusual volcanic activities and related deposits. Therefore, the fi rst aim of this fi eld trip will be to observe the two still active volcanic apparata of Stromboli and Vulcano, where the typical “strombolian” and “vulcanian” eruptive styles have been described. Moreover, well-known volcanic deposits, such as the obsidian lava fl ows of Rocche Rosse and the pumiceous pyroclastics of Monte Guardia, will be shown on the Island of Lipari. The detailed analysis of the structural and textural features of some well-documented pyroclastics and lavas will be focused on, with the aim of acknowledging the processes governing the eruptive activity. The Figure 1 - Location of the Aeolian volcanic islands and deposits related to low-medium energy eruptive associated seamounts. dynamics of acid and basic magmas (strombolian, of seven main islands (Alicudi, Filicudi, Salina, surtseyane, and vulcanian), that characterize the Lipari, Vulcano, Panarea, and Stromboli), and seven younger explosive eruptions of the Aeolian volcanoes, minor seamounts emplaced on a 15-20 km thinned will be analyzed in detail. The wide variability of continental crust (the Calabrian Arc) (Ventura et al., pyroclastic deposits that are present in Stromboli, 1999). Vulcano, and Lipari, and the broad compositional In the light of structural, seismological, and spectrum of emitted products, offer the possibility geochemical data (De Astis et al.,2003), the Aeolian of analyzing the depositional facies of an adequate volcanism may be divided into three main structural/ number of eruptions. Particular emphasis will be volcanological sectors (Fig. 2): given to the reconstruction of the transportation and emplacement mechanisms of pyroclastic deposits. For some well-documented eruptive sequences, the quantitative assessment of hazard will be proposed. Furthermore, special attention will be devoted to the observation of ancient marine deposits (on Lipari, Salina, and Filicudi), indicating the complex relationships between volcanic activity and Late Quaternary eustatic fl uctuations. Stratigraphical relationships between volcanics and raised ancient shorelines will be carefully described, showing the complex interaction between “local” volcanic and “global” Late-Quaternary eustatic events in the geological evolution of this volcanic apparatus. Volume n° 5 - from P37 to P54 n° 5 - from Volume Regional geological setting Figure 2 - Temporal evolution of the volcanism of the The volcanoes of the Aeolian Archipelago, and the Aeolian area, based on the available geochronological associated volcanic seamounts, form a ring-shaped data. From De Astis et al. (2003). structure (Beccaluva et al., 1985), around the subsiding Marsili basin (1.8-0.2 Ma; Savelli, 2000) a) A western sector, which extends from the Glauco and Marsili seamount (0.7Ma-active; Marani and seamount to the Alicudi and Filicudi Islands. In this Trua, 2002) (Figs. 1). sector, the volcanism developed between 1.3 Myr and The ring-shaped structure (the Aeolian Arc) consists 30-40 kyr (Beccaluva et al., 1982; 1985; Santo et al.,

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa feature oftheyoungerSalina,Lipari,and Vulcano phenomena amongthesemagmasareacommon dacites, andshoshonites.Mixingmingling less abundant high-Kcalcalkalinebasalts,andesites, and Lipari,weregenerallyeruptedtogetherwith Rhyolites wereemittedatPanarea, Vulcano, Salina, and, inalesseramount,trachytes(Criscietal.,1991). are associatedbothinspaceandtimetorhyolites bearing lavas wereemitted. These K-richmagmas ka ago,shoshoniticandsomeundersaturedleucite- during theyoungerstage,whichstartedabout40 calcalkaline basaltstodaciteswereerupted,whereas stage, productsrangingfromcalcalkalineandhigh-K activity (Beccaluva etal.,1985).Duringtheolder Aeolian volcanism ischaracterizedbyatwo-stage Petrological dataindicatethattheevolution ofthe 1997). expression ofNE-SWstrikingfaults (Volpi etal., complexes, whichhasbeeninterpreted asthesurface Gioia basinandthePanarea andStrombolivolcanic canyon, amorphologicalincisionlocatedbetweenthe et al.,1993). This isalsothestrike oftheStromboli affects theStromboliandPanarea Islands(Gabbianelli prevailing NNE-SSWtoNE-SWstrikingfault system seismicity characterizesalltheeasternseamounts. A 1991; Calanchietal.,1995a),andavery shallow Panarea (Gabbianellietal.,1990;ItalianoeNuccio, activity characterizesthesubmarinezonesaround 0.8 Ma,anditisstillactive atStromboli.Fumarolic seamounts. Inthissector, volcanism startedatabout and StromboliIslandstothe Alcione andPalinuro c) An easternsector, whichextends fromPanarea 1997). Continisio etal.,1997;Lanzafame andBousquet, scale Maltaescarpmentfault system(Ghisetti,1979; fault systemrepresentsthenortherntipoflarger structural depression(Barberietal.,1994). The TL volcanoes arealigned alongaNNW-SSE-striking TL) affects thevolcanoes ofthiscentralsector. These fault system(“Tindari-Letojanni” system,hereafter areas (Gamberietal.,1997). A NNW-SSE striking seismicity characterizelarge submarineandon-land (Keller, 1980).Fumaroles,hotspringsandshallow AD); atSalina,thelasteruptionoccurred13ka still active atLipari(580 AD) and Vulcano (1888-90 started at0.4Ma(Beccaluva etal.,1985),anditwas Salina, Lipariand Vulcano. Here,thevolcanism b) A centralsector, whichincludestheislandsof the tectonicsofthisarea(Calanchietal.,1995b). fault system(“Sisifo-Alicudi”system),characterized 1995; DeRosaetal.,1993a). A WNW-ESE striking 1 km eruptions alsoincreased:volumes intheorderof0.5- With theappearanceofrhyolites,energy ofthe al., 1993;DeRosaet1996;2003a). eruptions (DeRosaandSheridan,1983;Calanchiet western-central andtheeastern Aeolian arc(Fig.3). element ratiosandisotopicsignatures,betweenthe strong differences intermsofincompatibletrace Recent geochemicalandisotopicstudieshighlighted pyroclastics (e.g.Mt.Pilatopumice-coneatLipari). Panarea extrusions) orlow-energy strombolian fl evolved magmas,therhyoliteswereemitted as lava De Rosaetal.,2003b)]. When notassociatedwithless al., 1993);Mt.Guardia,22ka(Sheridanet1987; [e.g. thePollaraeruptions,24and13ka(Calanchiet a moreradiogenicSr-isotope signature,andshows contrast, theeasternsector(Panarea, Stromboli)has al., 2000,2003;GertisserandKeller, 2000).By et al.,1992;Francalanci1993;De Astis et unradiogenic Sr-isotope compositions(Esperanca magmatic arcgeochemicalsignatures,andrelatively Filicudi, Salina,Lipari, Vulcano), have typical Rocks fromthewestern-centralislands(Alicudi, ows, domes(e.g.obsidiansatLipariand Vulcano; 3 wereemittedduringsingleexplosive episodes Figure 3-K diagrams for Aeolian mafi 2 O/Na 2 O andTh/Hfvs.MgOvariation From De Astis etal.,2003. c rocks (MgO>4wt%). 26-05-2004, 15:04:00 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

trace element abundances intermediate between arc edifi ce. The subaerial part of the main cone was built and intraplate compositions, even if some Panarea up during the last 100 ka, through mainly effusive rocks show compositions partly similar to those of activity and minor explosive eruptions. Six main the mafi c rocks from Alicudi and Filicudi, and partly periods of activity characterized the volcanological intermediate between the compositions observed in history of Stromboli (namely, from the oldest to the two sectors of the arc (Peccerillo, 2001; Calanchi the youngest: Paleostromboli I, II, III, Vancori, et al., 2002a). Neostromboli, Recent Period) (Hornig-Kjarsgaard In conclusion, available geochemical, isotopic, and et al., 1993; Pasquarè et al., 1993); and they were fi eld data (e.g. Barker, 1987; Ellam and Harmon, recognized on the bases of structural changes and 1992; Esperanca et al., 1992; De Astis et al., 1997), stratigraphic unconformities. Several collapses of suggest that interaction between magma and upper crust is a signifi cant evolutionary process in the Aeolian arc. However, geochemical and isotopic studies on mafi c magmas, and on the crystalline basement, suggest that the main compositional differences between primary magmas are likely to have been inherited from a heterogeneous mantle source (De Astis et al., 2000, and references therein). The reasons for mantle heterogeneity are still a matter of discussion, although the majority of authors have suggested that it results from the interaction between various reservoirs, including MORB- and OIB-type mantle, and slab-derived sediments and fl uids (e.g. Francalanci et al., 1993; De Astis et al., 2000, 2003; Calanchi et al., 2002a). In a recent paper, De Astis et al. (2003) in the light of structural, seismological and geochemical data, suggest that the rapid transition from CA and HKCA, to SHO and KS, products may refl ect the transition from a collisional-type volcanism (CA), to post-collisional/rifting volcanism (SHO-KS). Therefore the late phase of the Aeolian volcanism may be mainly related to the rifting-type processes, more than to the subduction processes. In this framework, the Aeolian volcanism might be related to post-collisional extension processes in an arc collision zone.

Field Itinerary DAY 1 Stromboli Figure 4 - a) Panoramic view from the NE of Stromboli Volume n° 5 - from P37 to P54 n° 5 - from Volume Island; b) Simplifi ed geological map of the island, Stromboli stratovolcano, the northernmost island of showing dikes and volcano-tectonic features. 1 = eruptive the Aeolian volcanic arc, rises from a depth of about fi ssure; 2 = crater rim; 3 = fl ank and sector collapses; 2,000 m b.s.l., to an elevation of 924 m a.s.l. (Fig. 4), 4 = summit caldera; 5 = dike; 6 = young parasitic vent; lying up on a 20 km thick continental crust. 7 = active vent; 8 = Paleostromboli I, II and III lava,s The oldest subaerial rocks of the volcano, with an and pyroclastic rocks; 9 = Vancori lava sequence; 10 = age of 204 ± 25 ka (Gillot and Keller, 1993), is the Neostromboli lavas and scoriae; the Recent and present day lavas and pyroclastic rocks are indicated in white. Strombolicchio neck, located about 1.7 km NE of Numbers on the map refer to the different collapses. From Stromboli, and belonging to the same submarine Pasquarè et al. (1993).

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa Paleostromboli I andIII,pyroclastic deposits(fl which aremainlyconstitutedbylava fl lavas arecalc-alkaline,asPaleostromboli IIrocks, Hornig-Kjarsgaard etal.,1993).Strombolicchio few trachytes)(Fig.6)(Francalanci etal.,1989;1993; K andesites),andshoshonitic(shoshoniticbasaltstoa through high-Kcalc-alkaline(high-Kbasaltstohigh- alkaline (potassictrachybasaltsandshoshonites); alkaline (mainlybasaltic-andesites),topotassic- setting, anddisplayslarge variations, fromcalc- The rockcompositionistypicalofanorogenic et al.,1993; Tibaldi, 2001). present dayactivity takes place(Rosi,1980;Pasquarè of Stromboli(Fig.5),andthecraterterrace,where Sciara delFuocoscar, asteeptroughontheNWfl the formationofsomepeculiarfeatures,suchas collapses affected theNWpartofcone,leadingto later on.Inparticular, afterthe Vancori period,four Vancori period),andmainlyfl collapses before13ky ago(uptoandincludingthe building (Fig.4). They weremainlycraterandcaldera collapses), alternatedwithperiodsofvolcano different natures(crater, caldera, fl From Romagnolietal.(1993). mounded features; 5=slumpedareas;Cycanyon. identifi described inthetext.1=lateralwalls ofSciarascar;2= of SciaradelFuoco,withmainmorphologicalfeatures Figure 5-Shadedreliefmapofthesubmergedextension ed limitofthefan-shapeddeposits;3=levee; 4= ank andsectorcollapses ank, andsector ows. During ows. ank ow, are youngerthanPizzopyroclastic rocks(Hornig- by theproductsofpresentdayactivity, which by thehigh-KbasaltsofS.Bartololavas, and,thirdly, Fossa, withshoshoniticbasaltcomposition,secondly, by, fi than 5.6±3.3ka(GillotandKeller, 1993),areformed al., 1993). The rocksoftheRecentperiod,younger (Francalanci etal.,1989,1993;Hornig-Kjarsgaard the volcano, except fortheSciaradelFuocoscar composition, whichmainlyformtheNWpartof scoriaceous lava fl parts ofthevolcano. Neostromboli rocksarethin peak andtheyoungestoutcropsinSSE which eruptedshoshoniticlavas, formingthehighest period was mostlycharacterizedbyeffusive activity, alkaline composition,wereerupted. The Vancori surge, andfall) and lavas, withmainlyhigh-Kcalc- near oppositecorrelationexists forthecompatible with theincompatibletraceelementcontents,but a The potassiumcontentofrocksispositively correlated opaques arepresentasaccessorymineralphases. in latitesandbasaltic-andesites(Fig.7). Apatite and series, respectively. Orthopyroxene ismainlyfound products oftheshoshoniticandhigh-Kcalc-alkaline Biotite andhornblendeappearinthemostevolved phenocryst inthemafi the prevailing mineralphases.Olivine ispresentas 10 to55vol.%. Plagioclaseandclinopyroxene are textures, withphenocrystcontentsrangingfromabout Rocks mainlyhave holocrystallineporphyriticseriate Kjarsgaard etal.,1993). all theStrombolirocks. Dataarereportedonwater-free rstly, thepyroclastic coneofPizzoSoprala Figure 6-K bases. RedrawnfromFrancalanci etal.(1993). 2 O versus SiO ows, withpotassic-alkaline c rocks,uptobasicandesites. 2 classifi cation diagramfor 26-05-2004, 15:04:08 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

datings actually indicate that such a continuous state of activity started between the third and seven century A.D. (and continues to this day?) The typical activity of Stromboli consists of intermittent mild explosions, ejecting scoriaceous bombs, lapilli, and ash from vents where glowing lava stands at a high level in an open conduit (Ripepe et al., 2001; Chouet et al, 2003). The explosions occur when large bubbles of compressed gas burst

Figure 7 - Modal composition of the Stromboli rocks

at different degrees of evolution (SiO2 ranges). The mineral proportions are given on the total of phenocryst content. OLV = olivine; CPX = clinopyroxene; OPX = orthopyroxene; PLG = plagioclase; LEU = leucite (micro- phenocrysts); OPQ = opaques. Data from Francalanci et al. (1993). elements (Fig. 8). A broad positive correlation is also

present between K2O and Sr isotope ratios, with calc- alkaline magmas having lower 87Sr/86Sr than potassic- alkaline magmas (general range from 0.70519 to 0.70757, respectively). Some exceptions to this rule, however, do exist. In the Recent Period, for example, the basaltic shoshonitic scoriae of Pizzo Sopra la Fossa and the high-K basaltic lavas of S.Bartolo have higher 87Sr/86Sr than the older rocks with the same serial affi nity (Fig. 8) (Francalanci et al., 1988, 1989, 1993, 2003; Luais, 1988) The petrochemical variations of Stromboli rocks indicate that magmas underwent variable and complex differentiation processes. Simple fractional crystallization mainly affected shoshonitic and high-K calc-alkaline magmas, and potassic melts evolved through crustal assimilation associated with crystallization, whereas mixing and a combination of the previous processes occurred in different types of magma. Two magma reservoirs, at least, sited at different depths, were present all during Stromboli’s history. Variable partial melting degrees of a heterogeneous mantle wedge have also been proposed in order to explain the genesis of the different parental magmas (Francalanci et al., 1988, 1989, 1993; Luais, P37 to P54 n° 5 - from Volume 1988; Ellam et al., 1989; Vaggelli et al, 2003).

Present day activity The volcanic activity of Stromboli has been known and described since the Classical Age. However, Figure 8 - Diagrams of trace element contents (ppm,) historical sources older than 1000 A.D. are not and Sr isotope ratios, versus silica (wt %). Variations of accurate enough to assess if the activity was exactly incompatible and compatible trace elements are generally the same as we see it today. Stratigraphic data and 14C similar to those of Rb and Ni contents, respectively.

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa CO and consistingmainlyofH with anestimatedoutputof6,000-12,000t/day is associatedwiththecontinuousstreamingofgas, time interval being10-20min.Explosive activity and take placeatregular intervals, themostcommon fragments. The explosions lastforafew seconds, formation ofajethotgas,andincandescentlava at thesurface ofthemagmacolumn,resultingin abundant mineralphase( and microphenocrysts).Plagioclaseisthemost seriate texture (ca.45-60vol% ofphenocrysts Blackscoriaeandlavas have ahighlyporphyritic activity have remainednearlyconstant. rocks eruptedsincethebeginning oftheStrombolian The chemicalandpetrographiccharacteristicsof two typesofmagma(Rosietal.,2000). A.D. anditseemstobeassociatedwiththepresenceof Strombolian activity began betweenIIIand VII century often intermingledinthesameejecta. This persistent et al.,2001).Blackscoriaeandlightpumiceare et al.,1999,2003;Bertagnini1999;Métrich “LP magma”)(Bonaccorsoetal.,1996;Francalanci a volatile-rich, Low Porphyriticmagma(hereafter with ahighlyvesciculated lightpumice,representing component isanHPmagma,whicheruptedtogether and paroxysms. The mostvoluminous juvenile magmas are,instead,eruptedfrommajorexplosions magma (hereafter“HPmagma”). Two typesof fl Black scoriae,scoriaceousbombsandlapilli,lava two villagesonthecoast. of kilometersfromthecraters,andoftenaffecting the blocks, andincandescentfragmentswithinadistance violent explosions occur. They produceshowers of (Bertagnini etal.1999).Lessfrequently, muchmore per yearhasoccurredover thepast100years from thecraters.Onaverage, two orthreeexplosions blocks withinadistanceofseveral hundredsofmeters short-lived blaststhatejectmeter-sized spatter, and violent explosions. Mid-scaleexplosions consistof lava fl activity ofthevolcano isperiodicallyinterruptedby minor HClandHF(Allardetal.1994). The routine mineral phaseinsize,generallyrangingfrom64% bands ofdiopside.Olivine is thesecondlargest augite composition,but usuallyshowing internal clinopyroxene (up to 1cmlong),withaprevalent normal intherims. The largest phenocrystphaseis ranges from60%to87%,thezoningiscomplex but The anorthite(An)contentofplagioclasegenerally clinopyroxene ( ows areformedbyavolatile-poor, HighlyPorphyritic 2 (2900-5800t/day),SO ows withintheSciaradelFuoco,andbymore ≈ 15vol%), andolivine ( } ≈ 35vol%), followed by 2 (400-800t/day),and 2 0 (3200-6300t/day), ≈ 5vol%). signifi 0.70615 ofpresentdayscoriae.Pumicesampleshave then startsmoothlytodecrease,upthevalue of 85 A.D., areconstant,withanaverage of0.70626, the beginning ofthe20 Fig. 10). evident formostofthemajorandtraceelements(e.g. shoshonites, withK shoshonitic basalts,but scoriaeandlava glassesare those ofscoriaeandlavas: pumiceglassesarestill of pumicearesharplydistinctincompositionfrom and lavas (Fig.9),whereastheglassygroundmasses Pumice samplesareslightlylessevolved thanscoriae 1999, 2003;Rosietal.,2000;Métrich2001). high-K toshoshoniticbasalts(Francalancietal., Scoriae, lavas andpumicecompositionsrangefrom An >80%.(Francalancietal.,2003). from 60%to90%,withequilibriumcrystalshaving usually reverse. An contentofplagioclaseranges as clinopyroxene inscoriaeandlavas, but zoningis Clinopyroxene shows thesamecompositionalrange Phenocryst zoningissometimeslarge andreverse. equilibrium withthegroundmassisaround81-86%. olivine isfrom68%to86%,but thecompositionin proportions inthedifferent samples.Fo contentof olivine, clinopyroxene andplagioclase,withvariable %), withglassygroundmass.Mineralsconsistof has poorlyporphyriticseriatetextures (<10vol to 74%ofForsterite (Fo) content.Lightpumice (Francalanci etal.,1999,2003;Métrich2001). as mixing,associatedwithfractionalcrystallization day activity ofStrombolican, therefore, bededuced evolution affecting themagmaswhichfeedpresent to thatoftheHPmagma. The pre-eruptive processof characterized bydifferent physico-chemical conditions magma, whicharrives fromadeeperreservoir, anditis erupted aslightpumice,representsthereplenishing state conditionsaremaintained. The LPmagma, and replenishedshallow reservoir, wherethesteady and evolves inacontinuouslyerupting,crystallizing has beenalsosuggestedthattheHPmagmaresides Francalanci etal.,1999;2003;Rosi2000).It Allard etal.,1994,2000;HarrisandStevenson, 1997; from theStrombolianactivity (Gibertietal.,1992; of thehomogeneouscompositionrockserupted on thebasesofthermalandgasbudget balances,and plumbing systemofStrombolihave beenhypothesized The generalsteadystateconditionsofthepresent same (around0.51256)(Francalancietal.,2003). major eruptionsin1996and1998 A.D., arenearlythe isotope ratiosofscoriae,lavas, andpumicefromthe 87 Sr/ 86 cantly lower Srisotoperatiosthanscoriae,with Sr

≈ Sr isotoperatiosofscoriaeandlavas from 0.70610(Francalancietal.,1999). 2 O between3.5-5.2wt%. This is th centurytoaround1980- 26-05-2004, 15:04:19

Nd

GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

2002, and April 5, 2003, when a large tsunami wave hit the village of Stromboli and blocks fell on Ginostra.

Onset of the activity and Sciara del Fuoco slope failure The volcanic crisis started on December 28, 2002, when voluminous, unusually fast-moving lava fl ows were issued from several vents in the NNE sector of the Sciara del Fuoco. Lava fl ows reached the sea in various places, giving rise to moderate explosions and vapor emission. Between 28 and 30 December the lava fl ow activity was accompanied by signifi cant displacement seawards of masses of volcanic materials, thus forming the infi ll of the Sciara del Fuoco, and by the formation of moderate volume debris avalanches. At 1:15 p.m. of 30 December 2002, slope perturbation, caused by Figure 9 - K2O versus SiO2 classifi cation diagram showing the compositional fi elds for the rocks of the present day eruptive phenomena, culminated in the catastrophic activity of Stromboli, including the scoriae and lavas from failure of the northern sector of the Sciara slope. the 2002-2003 eruptive crisis. Data are reported on water- Surveys conducted in January 2003 revealed that the free bases. Data unpublished and from Francalanci et al. collapse involved an elongated, irregularly-shaped, (2003,) with references therein. rock body with a maximum thickness of about 40 meters, which detached from both the subaerial and submarine portion of the Sciara, between 600 m a.s.l. and 600 m b.s.l.. The catastrophic failure resulted in a strong sea level perturbation, and the concurrent generation of tsunami waves, which hit the village of Stromboli causing substantial damage, and a few injuries. The maximum height of the tsunami waves which hit the village, was about 9 m. The opening of an effusive vent at an elevation of 500 m caused the drop of the magma level in the volcano conduit, the collapse Figure 10 - Variation of MgO contents over time, for the of the summit craters, and immediate cessation of the glassy groundmasses of the scoriae, lavas, and pumice erupted by the present day activity of Stromboli, including Strombolian activity. the 2002-2003 eruptive crisis. Data unpublished and from Francalanci et al. (2003). Effusive eruption From 30 December 2002, to 14 February 2003, the 2002-2003 eruptive crisis volcano produced continuous lava emissions from a During the fi rst seven months of 2003, Stromboli vent located at about 500m a.s.l. By mid-February, produced the most intense and dangerous eruptive the effusive vent moved eastwards at about 550 m crisis of the past three centuries. Due to the threat of a.s.l.. From mid February to 21 July, the effusive (and eventual) slope failure and tsunami, part of the vent remained more or less stable, and the effusion resident population voluntarily left the island using rate progressively declined. By the end of the effusive air transportation facilities made available by the eruption, the scar produced on the 30 December had national Civil Protection authorities. The eruptive been partially fi lled up, and a new lava bulge had been P37 to P54 n° 5 - from Volume crisis started on 28 December 2002, and ended on 21 formed in the eastern sector of the Sciara, as a result July 2003, when the volcano returned to its normal of lava accumulation. Preliminary estimates indicate state of persistent activity. The volcanic crisis consisted that the total volume of the erupted lava was in the in the combination of the following eruptive phases order of 10 million of m3. (Bonaccorso et al., 2003): I) the onset of the eruption, and the Sciara del Fuoco slope failure, ii) effusive Paroxysmal explosion of April 5, 2003 eruption, and iii) the paroxysm explosion of 5 April, In the fi rst half of April, three explosions occurred 2003. The volcanic hazard climaxed on December 30, in the summit craters on the 3 th, 5 th and 10th of this

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa (volume 1-1.5km Sciara delFuocoinstability the previously eruptedpumice. reveals Srisotoperatiosofabout0.70611,similarto the lava fl 0.70616, showing somefl blocks (fromparoxysm),rangebetween0.70614to whole rocks,andgroundmassesofscoriae,lavas and not changesignifi Even pumicefrom5 plagioclase, large clinopyroxene, andolivine. activity, withphenocrystsofprevalent andsmaller different fromthoseoftheprevious Strombolian eruptive crisisarehighlyporphyriticrocks,not Scoriae andlavas eruptedduringthe2002-2003 mountain. blocks andpumiceousbombsintheupperpartof wave. The explosion depositedafamiliar blanket of reported broken windows duetothetransitofashock falling blocks.Inthesamevillage,somehouses water tankwereseverely damagedbymeter-seized on theSWsideofisland,ahouseandrain- Km fromthecraterarea.InvillageofGinostra, and SWfl hundreds ofmetersabove thevent fellbackontheNE and Basiluzzo.Meter-sized blockslaunchedseveral the fallout ofpumiceintheseabetweenStromboli This columnwas blown southbythewind,producing a dark,2kmhigh,convective column(Calvari, 2003). blocks andincandescentfragments,whichgenerated violent. The explosion consistedofavertical jetof 9:12 a.m.localtime,was suddenandbyfar themost month. The explosion whichoccurredon April 5that volume of2-3km which affected the Vancori edifi of thenorthwestfl Stromboli hasproducedatleastfourmajorcollapses inferred fortheperiodolderthan13ka.Sincethen, failure ofitsfl dominated bycalderacollapsesandthegravitational The morphostructuralevolution ofStrombolihasbeen the scoriaeandpumiceof5 the compositionsofglassygroundmasses(including and lessevolved scoriaeandlavas (Figs.9,11).Even the samecompositionalfi scoriae andlavas (datauptoJanuary2003)plotin Whole rockdataofmajorandtraceelementsfor differences fromthatoftheoldermineralphases. composition seems,however, toreveal somesmall the previously eruptedpumice. The mainmineral any importantpetrographicchangesinrelationto ank ofthevolcano, uptoadistanceof1.5-2 ow eruption.Pumicegroundmassanalysis anks. Calderastructureshave been cantly (Fig. 10).Srisotoperatiosin 3 3 ank ofthecone. The olderone, ), beheadeda900mhighcone, . The following collapseepisode th April 2003doesnotshow uctuations beforeandafter elds aspreviously erupted th ce, hadanestimated April paroxysm)do collapse), duringwhichvolumes ofabout1.08km another gravitational failure (TheSciaradelFuoco la Fossa edifi was formed(PizzoSopralaFossa). The PizzoSopra area. After thisevent, anabout1000mhighcone whose summitwas situatedabove thepresentcrater turn, canproduceseaperturbations. unstable andexposed togravitational collapsethat,in of reposethematerials,andasaresult,slopeis slope oftheSciarais40-45°,very closetotheangle by seawave action. The subaerialandsubaqueous debris suppliedbyfast abrasionwhichwas produced sea level, materialisentirelymadeupofvolcanic with subordinateintercalationsoflava fl part oftheSciaradelFuoco,consistsloosedebris Material presentlyaccumulatedwithinthesubaerial generated thepresentdepressionofSciara. of volcanic materialslidintothesea. The lastone The lavas, whichwere,eruptedbyalocaleruptive center. Upper Paleostromboli Ihigh-Kbasaltic-andesite (Paleostromboli III), iswellexposed. Itoverlies the of pyroclastic depositsandlavas ofthe island (closetotheStromboliharbour),sequence In thelocalityof“LaPetrazza”,inNEfl Stop 1.1: variation ofBaandNicontentsover timefor therocks of the presentdayactivityofStromboli.Dataunpublished, Figure 11-Compositionofscoriaeandlavasfromthe eruptive crisisof2002-200,3andcomparisonwiththe Scari complex ce was inturnlargely dismantledby isrestrictedtothispartofthe and fromFrancalanci etal.(2003) with references therein. Scari complex ows. Below ows. ank ofthe 26-05-2004, 15:04:31 3

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COA (“Centro Operativo Avanzato”), an integrated structure where data produced by the monitoring activities are evaluated in team with Civil Protection personnel for the management of the volcanic crisis. An effi cient radio link between Stromboli, the Aeolian Archipelago, and northern Sicily and Calabria, was also set up. Main scientifi c institutions involved in the volcano monitoring activities at Stromboli are: INGV (National Institution of Geophysics and Volcanology), JRC (Joint Research Centre of the European Community), and the University of Florence. During the fi rst half of 2003, instrumental networks were substantially expanded and upgraded to monitor volcanic activity, the slope dynamics of the Sciara, and tsunami wave generation. Principal current networks include: broadband seismic network Figure 12 - Location of stops (INGV), seismic-acoustic network (U. Florence), continuous ground gas emission (INGV), continuous island, possibly deriving from a local vent. It is a gas streaming from the summit craters (INGV), Radon sequence of up to 50 m thick pyroclastic deposits (Rn) monitoring (U. Turin), ground-based, Linear with a lava fl ow unit subdividing the Scari tuffs into SAR (Lisa) (JRC Ispra – U. Florence), total station Lower and Upper Scari Tuffs (LST, UST). The lava (INGV), continuous GPS stations (INGV), Tiltmeters fl ow, showing scoriaceous aa-breccias at top and , and (INGV), two ondameters (Civil Protection), and with an age of 34.6 3 ky (Gillot and Keller, 1993), is ± optic and thermal videocameras (INGV). Periodic a shoshonite (SiO = 52.5wt% and K O = 2.5wt%), 2 2 topographic and bathymetric surveys were also with prevalent plagioclase phenocrysts, followed by conducted by the University of Rome “La Sapienza” large clinopyroxene and olivine. and by the IGM – CNR of Bologna. The LST is a sequence of dominantly Strombolian air- fall layers of 10 cm to 2 m thick, constituted of scoriae The ascent to the top of Stromboli (918 m. a.s.l.), and lapilli, with some bombs and lava fragments. Thin to observe the active cone of the present day bands of brown ashes are often interbedded with the Strombolian activity, starts with a small street passing fall deposits. Intercalated in the basal part is the alkali- between the houses of Piscità towards the Labronzo trachytic marker tephra of the Aeolian Islands, known lighthouse. Passing through the houses of Piscità, it is as “Ischia Tephra”. It is a 25-30 cm thick tephra layer, possible to observe to the left (looking at the volcano) composed of a yellowish, well-sorted fi ne ash. The the morphology of the NE fl ank of the volcano, juvenile components of LST, from the bottom to the consisting of several hills corresponding with young top, vary from high-K basalts to shoshonite. (<13 ka) lateral vents and eruptive fi ssures. These The UST starts with a sequence of strombolian are aligned along the NE-SW direction, which is the lapilli beds, similar to those of LST. These fall units most important tectonic direction of the recent period, are followed by a phreatomagmatic series, which is along which the active craters and the feeding dykes formed by coarse explosion breccias with scoriaceous are also lined up. The houses of Piscità, in particular, bombs and large blocks, overlain by a crudely-bedded are built up on the San Bartolo black lavas, erupted surge and lahar series. The latter is constituted of by one of these lateral vent less than 6 ky ago, and sand-wave bed forms, low angle cross-bedding, ash- forming lava tunnels visible at the beach. They are P37 to P54 n° 5 - from Volume rich beds with accretionary lapilli, and these form high-K basalts, rich in olivine, clinopyroxene and the terrace cliff above the houses of Scari-Pizzillo. plagioclase phenocrysts, and xenoliths of cumulate Juvenile caulifl ower bombs and scoriae range from origin. The path continues up to the top on the shoshonitic basalts to shoshonites. Neostromboli potassic lavas, which can be observed several times during the ascent. They are potassic Stop 1.2: trachybasalts to shoshonites, with very evident As a result of the eruptive phenomena of 2002- phenocrysts of clinopyroxene, followed by olivine 2003, the National Civil Protection set up, the and plagioclase (Figs. 6-8).

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa a.s.l. Large blocks eruptedbytheparoxysmof5 are alsovisiblearoundthepathfromabout400m major eruptionsandparoxysms(e.g.1930eruption?), Scoriae andpumiceeruptedduringthemorerecent the Neostromboliperiod. occurrance ofhighlyexplosive activity attheendof ash bedsrichinaccretionarylapilli,andtestifytothe deposits arefound. They aremainlyconstitutedof bolilavas, several outcropsoftheLazzaropyroclastic Continuing towards thetop,above theNeostrom- evident. the northernpartofSciaradelFuoco,isparticularly afar. The 2002-2003lava fl blocks, lavas andash),canbealsoobserved from Strombolian activity (scoriaceousbombsandlapilli, Fuoco, representingtheproductsofpresentday several dykes (Fig.4). The depositsofSciaradel along thesidesofSciaradelFuoco,andcutby aa scoriaeisvisiblebelow, exposed bythecollapse The sequenceofNeostrombolilavas andassociated lateral collapseoftheNWpartcone(Fig.5). the deepscarformedinpresentshapebylast time ontheimpressive view ofSciaradelFuoco, At about300ma.s.l.,thepathopensforfi Stop 1.3: the NEcrater, whichisusuallythemostactive, and strombolian explosions take placefromthevents of fi On average, thereareaboutthree craterswithabout the intermittentmoderateStrombolianexplosions. to have animpressive view ofallthecraters,and vents, itispossible (withgoodweatherconditions), the endofascent.Being150mabove theactive The topofPizzoSopralaFossa (918ma.s.l.)is Stop 1.4: vents presentintheNEsectorofvolcano. (Neostromboli), andtothesiteofotherlateral to have alooktotheeruptive fi The view down towards Strombolivillage, allows us depression. period, whichdiptowards theSciaradelFuoco are indiscordancewiththedepositsofRecent bearing latitesandtrachytes)breccias,which a narrow ridgeontheUpper Vancori lavas (biotite- leaves theNeostrombolirocks,andpassesthrough Just beforetheLiscionepeak(865m.a.s.l.),path well observed fromabout750m.a.s.l.. The Strombolianactivity fromtheNEcratercanbe April 2003starttobefoundfromabout500ma.s.l. ve eruptive vents continuouslydegassing. Typical ow, widespreadallover ssure of Vallonazzoof ssure rst th

activity eruptions. the lapilliandcoarseashemplacedbynormal clinopyroxene crystals(augite)canbecollectedfrom “Fossetta” valley, whereassingle,well-preserved, recent majoreruptionscanbeseentowards the Scoriaceous bombs,blocks,andpumicefromthe as areseveral geologicdiscordances. younger lateralcollapses,arealsovisibleallaround, (at about13ky) (Fig.4). The rimsofthis,andthe by thefi and highestpeak(924ma.s.l.)ofthevolcano, cut lavas andafew pyroclastic rocks,formingtheclose It isalsopossibletoobserve the Vancori sequenceof shoshonitic juvenile composition. discordant pyroclastic falls andfl Sopra laFossa yellow tuffs, whicharecomposedof During thedaytime,wecanhave alookatthePizzo different magmafountains. it ispossibletoestimatetherealsizeandshapeof We willwait hereuntildusk.Indeed,onlyinthedark, over time. in thecraterterrace,however, issubjectedtochange from theSWcrater. The morphologyanddynamics stratigraphical successionwillbestronglyconditioned the island;asaconsequence,descriptionof sun exposure, weproposeacounterclockwisetourof fl between volcanic activity andLateQuaternaryeustatic special attentionpaidtothecomplex relationships stratigraphical evolution oftheislandLipari,with The seconddaywillbedevoted toillustratingthe uctuations. Inordertohave thebestconditions of Figure 13-Bathymetricsketch mapofthe Aeolian Arc rst hugelateralcollapsetowards theNW DAY 2 (southern Tyrrhenian Sea) ows, withabasaltic 26-05-2004, 15:04:38 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

by the succession of outcrops encountered along Detailed evaluation of stratigraphic relationships to the tour. The stratigraphy is defi ned by taking into the volcanic substratum, allows for their correlation account the relationships between volcanic products with Late-Quaternary eustatic highstands of and ancient marine deposits of Tyrrhenian age: Tyrrhenian age, corresponding to marine oxygen therefore, the volcanic succession will be described isotope substages (MIS) 5e, 5c, and 5a, dated to 124, in terms of pre-Tyrrhenian, Tyrrhenian and post- 100, and 81 ka, respectively. Tyrrhenian age units. The alternation of marine deposits with volcanics allows for main unconformities to be defi ned in the Lipari stratigraphy of Lipari, and these represent signifi cant The Island of Lipari represents the emerged portion of hiatuses of volcanic activity. The unconformities have a broad volcanic edifi ce that rises about 2000 m from been produced by marine erosional episodes which the sea fl oor in the central sector of the Aeolian Arc, corresponded to the discrete eustatic highstands, and in the southern Tyrrhenian Sea (Fig. 13). following subaerial erosion. The hierarchy of the The age of volcanic activity on Lipari ranges from at unconformities is established by taking into account least 223 ka to the present time. This age span takes the potential extensibility at a regional scale. By into account dates derived by K/Ar (Cortese et al., taking this approach, two fi rst order unconformities 1986; Gillot, 1987; Crisci et al., 1991), Ar/Ar (Lucchi, (UI and UII), have been introduced (Tranne et al., 2000a) and 14C techniques (Crisci et al., 1983; Losito, 2002), thus fi xing the boundaries of the marine 1989). deposits of Tyrrhenian age (Figs. 15a,b and 16), Indicators of three raised fossil shorelines (Fig. 14), which have been correlated on most of the Aeolian located at elevations of 43-45 metres asl (I order), archipelago. UI is the marine erosional surface related 23-27 m (II order), and about 12 m (III order), are to the eustatic highstand, corresponding to MIS 5e, recognized on the Island of Lipari (Calanchi et al., whereas UII is the erosional surface produced by 2002b; Lucchi et al., 2003). strong subaerial erosion processes, which are related to the sea level lowering at the end of MIS 5. Although not syncronous, these unconformities developed over a short time span and, therefore, they assume an important chronostratigraphic signifi cance, and allow main stages in the geological evolution of Lipari to be put in evidence (Fig. 15b). The building of the island has been described as the result of two mainly constructive stages of strong volcanic activity, pre-Tyrrhenian and post-Tyrrhenian, spaced out by the Tyrrhenian stage and characterized by the alternation of marine erosional episodes with volcanic activity (Figs. 15a,b, and 16). The pre-Tyrrhenian stage ranges in age from ca. 220 ka to 124 ka (Fig. 14b), and consists of several episodes of strong volcanic activity, during which the products of the Paleolipari informal unit and Piano Grande Synthem (Fig. 15a, b) were emplaced. • The Paleolipari informal unit includes the oldest outcropping products (scoriaceous deposits, lava fl ows, and subordinate hydromagmatic P37 to P54 n° 5 - from Volume pyroclastics), CA basaltic-andesite in composition. They are related to the mainly strombolian and effusive volcanic activity of several eruptive centers located along the west coast (Timpone Carrubbo, Monte Mazzacaruso, Figure 14 - Geomorphological and volcano-tectonic Timpone Pataso, Timpone Ospedale, Valle di sketch map of Lipari, and distribution of the Tyrrhenian Pero, Pietrovito, and Chiesa Vecchia; Fig. 15, fossil shorelines (from Tranne et al., 2002; modifi ed). sections c-o) and, subordinately, in the central-

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa Figure 15-Geologicalsketch mapofLipari(fromLucchi etal.,2003;modifi ed ). 26-05-2004, 15:04:47 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

Fig. 16 - Correlation of stratigraphic sections along the west coast of Lipari (from Lucchi et al., 2003; modifi ed). Symbols: (1) main stratigraphic units (see Fig. 15); (2) “cordierite-bearing lavas” and “leaf-bearing pyroclastics” (Pulera and Timpone del Grado formations; see Fig. 15); (3) main stratigraphic correlations; (4) and (5) minor stratigraphic correlations; (6) paleosol; (7) I order fossil shoreline (slt; see Fig. 15): A, littoral conglomerates; B, cemented littoral conglomerates; (8) II order fossil shoreline (pcl; see Fig. 15): A, littoral conglomerates; B, sands; (9) III order fossil shoreline (fo; see Fig. 15): littoral conglomerates; (10) “cordierite-bearing lava” pebbles; (11) lapilli tuffs and tuffs; (12) pumiceous pyroclastics; (13) loose scoriaceous lapilli; (14) welded scorias; (15) stratifi ed pyroclastics; (16) clastogenic lavas; (17) exotic pyroclastic layers; (18) massive lava; (19) columnar-jointed lava; (20) brecciated lava or carapace; (21) dyke; (22) slope detritic deposit; (23) fault. eastern sector of Lipari (Monterosa, Timpone sector of Lipari. Lavas of the Mt. S.Angelo Croci). Radiometric ages of 223±0.9 ka (K/Ar eruptive centre are dated to 127±8 ka (K/Ar date, date; Crisci et al., 1991), 150±10 and 127±9.5 Crisci et al., 1991). P37 to P54 n° 5 - from Volume ka (K/Ar average dates; Gillot, 1987) have been The Tyrrhenian stage, ranging from 124 to 81 ka obtained for these products. (Fig. 15b), was characterized by recurrent sea- • The Piano Grande Synthem comprises lavas level highstanding episodes, during which marine and hydromagmatic pyroclastics (CA to HKCA reworking processes occurred on the coastal slopes basaltic-andesite, to andesite in composition) of the growing volcanic edifi ce, and caused the related to the fi rst phase of volcanic activity of emplacement of marine conglomerates, sands, and the NNW-SSE aligned Mt. S.Angelo and Mt. terraces. This stage is also characterized by several Chirica stratovolcanoes, located in the central episodes of volcanic activity, with the emplacement

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa in thePuntaLeGrotticelleSupersynthem,which of exotic provenance. These volcanics areincluded activity, andwiththeemplacementofpyroclastics the occurrenceofseveral episodesofstrongvolcanic portions oftheislandLipariwerebuilt up,with time span,mostofthesouthernandnorth-eastern bsl (ChiocciandRomagnoli,inpress).Duringthis been recognizedatanaverage depthof 105-120m likely formedduringthelastglaciallowstand, has In particular, awell-developed marineplatform, of thevolcanic edifi that marineerosionanddepositionaffected portions of thetime,considerablylower thanatpresent,so 81 katothepresenttime,sea-level was, formost During thepost- • • • Synthems (Fig.15a,b). the ScoglioLe Torricelle, Bruca,andFontanelle the CalaFicoSupersynthem,whichisdivided into volcanic deposits are stratigraphicallycomprisedin stratocones. The resultinginterbeddedmarineand to thebuilding oftheMt.S.AngeloandChirica of large volumes oflavas andpyroclastics related 100 kaand81ka,respectively. which areattributed toMIS5cand5a,dated Punta delleFontanelle lithosomes,Fig.15b), of IIandIIIorder(PuntadelCugnoLungo interbedded withtheraisedmarineconglomerates Chirica 2lithosome). The volcanic productsare 92±10 ka)andMt.Chiricastratocones(Monte Angelo (MonteS. Angelo 3lithosome,datedat related tothefi The Fontanelle Synthemcomprisesthevolcanics sections l-n). lavas and CAandesitelava fl pyroclastics” 15a, b):they consistofpeculiar stratocone (MonteS. Angelo 2lithosome;Fig. made upthemainportionofMt.S.Angelo The BrucaSynthemincludesthevolcanics which reworked conglomeratesoutcrop). (up to20-25metersnearCalaSciabeca,where dei Lacci,withanaverage thicknessof2m sector betweenP. delLegno Nero,and Vallone The conglomeratesoccurinthewesterncoastal highstand, correspondingtoMIS5e(124ka). which isattributed tothe Tyrrhenian eustatic (at anelevation of43-45masl;Fig.14) c-d, f-m)relatedtotheIorderfossilshoreline the marineconglomerates(Fig.16,sectionsa, The ScoglioLe Torricelle Synthemincludes 105 ± 19 ka(Puleraformation;Figs.15band16 ”), thelatteronesdatedto104 Tyrrhenian (Timpone delGradoformation), nal building stagesoftheMt.S. ce whicharenow submerged. stage,ranginginagefrom ows(“ cordierite-bearing “leaf-bearing ± 3.5 kaand • • Bianco Synthems(Fig.15b). is divided intothe Valle Muriaand Vallone Fiume the well-known, widespread“ the exotic tephras,atleasttwelve layersof with tephrasofexotic provenance. Among the entireIslandofLipari,andareinterbedded “ These pyroclastics, inparticulartheonesof precede therecurrenteffusive phases ofactivity. are emplacedduringexplosive phases,which The pumiceoushydromagmaticpyroclastics (Tranne the 37-23ka,22-20and13-11katimespans third, andthefourthoneswereemplacedin date; Gillot,1987),whereasthesecond, correlated tothe“ have beenidentifi activity, ranginginagefrom11.4 and fl the emplacementofviscousrhyoliticlava fl phases, andtheselatterwerecharacterizedby hydromagmatic phases,whichprecededeffusive widespread, andwereemplacedduringexplosive sector ofLipari. The pumiceouspyroclastics are volcanic activity focusedinthenorth-eastern composition, whicharerelatedtotherecurrent pyroclastics andlavas, HKCArhyolitein The Vallone FiumeBiancoSynthemcomprises (Tranne etal.,2002,andreferencestherein). Tuff” succession), and13ka,(theageofthe“ “ interval betweenmorethan70ka,(theageofthe succession was emplacedinthechronological represents asignifi form apeculiarpyroclastic successionwhich The interbeddedlocalandexotic pyroclastics (Tranne “ date; Crisci of effusion ofdomesisdatedto42 HKCA rhyoliteincomposition. The fi NNW-SSE andN-S-alignedvolcanic domes, phases characterizedbytheemplacementof pyroclastics associatedwithfoureffusive of widespreadpumiceous,hydromagmatic in easternLipari. These productsconsist southern sectoroftheisland,andsubordinately and thisactivity ismainlyfocusedinthe related torecurrentstrongvolcanic activity, The Valle MuriaSynthemincludesthe products Island ofSalina,the“ Monte Guardia sequence”, Grey Porri Tuffs Lower Pollara Tuffs layerlocatedatthetopofsuccession) owing domes.Several phasesofvolcanic et al et al et al ., 2002,andreferencestherein). ., 2002,andreferencestherein). ” locatedatthebottomof ., 1991)and40.5 cant stratigraphicmarker: the ed, together withtephras Grey Porri Tuffs ” fromtheIslandofSalina Ischia Layer arewidespreadover Brown Tuffs ± ± 1.8 ka(K/ar ± ” fromthe 3 ka(K/Ar ” andthe 3.1 (K/Ar rst phase rst 26-05-2004, 15:04:58 Brown ows ” GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

date; Crisci et al., 1991) to about 1.3 ka (Cortese Punta le Grotticelle (Fig. 18) allows us to estimate the et al., 1986), occurred with regard to the eruptive maximal age for the corresponding marine platform centers of Vallone di Gabellotto, Monte Pilato, (Lucchi, 2000a). and Forgia Vecchia. A fl ight of three fossil shorelines has been inferred from the evaluation of main morphological features, Fossil shorelines such as inner margins and notches, and of the cross- Raised fossil shorelines are recorded along most of the cutting relationships (Lucchi et al., 1999; Calanchi et west coast (between Punta le Grotticelle and Punta del al., 2002b; Lucchi et al., 2003). The fossil shorelines Legno Nero; Fig. 2), and only in a few places along the occur (Figs. 13 and 15) at the present elevation of east coast (nearby Porto Pignataro and Monterosa) of 43-45 m (I order), 23-27 m (II order), and ~12 m Lipari (Calanchi et al., 2002b). Along the west coast, (III order). A continuous and complete threefold fossil shorelines occur mainly on the steep coastal staircase did not form, or has not been preserved on cliffs, and are indicated by sloping, terraced surfaces, the island, because the shorelines may be missing or whose present distribution is strongly conditioned laterally discontinuous, owing to subaerial reworking both by the covering of more recent deposits, and by subaerial and submarine reworking processes. The most visible feature consists of marine platforms (capped by littoral conglomerates), whose inclined sections outcrop at different elevations (Fig. 17).

Figure 17 - At Cala Fico, the I order terraced surface (mp = marine platform, at elevation of 30-40 m asl; co = littoral conglomerates of the Scoglio le Torricelle Synthem; see Figure. 15) cuts lavas and pyroclastics (A) which are related to the Paleolipari informal unit (M. Mazzacaruso eruptive centre). The surface is capped by the Valle Muria Synthem pyroclastic succession (B). (From Lucchi et al., 2003; modifi ed).

In places, transversal sections of the original terraced surfaces have been observed: there, particular Figure 18 - Emergent remnants of fossil shorelines attention has been devoted to the identifi cation (and (from Lucchi et al., 2003; modifi ed). (a) Terraced to the measurement of the elevation) of the inner surface occurring on the steep coastal cliff at Cala terrace margins or of the marine notches (Fig. 18a, b), Fico (im = inner margin, at elevation of ca. 45 metres asl; pc = palaeocliff; mp = marine platform; co = as these are considered as representing the shoreline littoral conglomerates); this surface cuts massive lavas at the time of a sea-level peak. (A) related to the Paleolipari informal unit (Monte Volume n° 5 - from P37 to P54 n° 5 - from Volume Marine deposits consist of cliff base conglomerates Mazzacaruso eruptive centre) and is extensively capped by capping the marine platforms, of reworked the pyroclastic succession of the Valle Muria Synthem (B). conglomerate deposits lying on submarine erosional (b) Terraced surface occurring on the steep coastal cliff surfaces, and of submerged beach sands. A detailed at Punta le Grotticelle (im = inner margin, at elevation of lithological study of the conglomerates has provided 25-27 metres asl; pc = palaeocliff; mp = marine platform; co = littoral conglomerates); the surface cuts massive relevant stratigraphical constraints: the presence lavas (A) related to the Paleolipari informal unit (T. of pebbles of “cordierite-bearing lava” (Pulera Carrubbo eruptive center) and is covered by ancient slope formation; Figs. 14b and 15, sections l-n) in the detrital deposits (de). (From Lucchi et al., 2003; modifi ed). littoral conglomerate outcropping between Bruca and

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa 2003; modifi hinder thestratigraphiccontacts.(From Lucchi etal., (C), andbyrecentdetritaldeposits(D),which partially capped bythepyroclasticsof Valle MuriaSynthem of thispeculiarlithotype.Thestratigraphicsuccessionis platform) andIIIorder(co conglomerates; mp because theco stratigraphically lieonthe“cordierite-bearinglavas”(B) deposits andarenotaffected bythefaults.Bothsurfaces marine platform) terracedsurfacesovercut thedetrital Shackleton (1986),whichhasnotbeenmodifi curve, e.g.the curve proposedbyChappelland and indirectlydated,tothepeaksofaglobaleustatic the staircasedshorelinescanthereforebecorrelated, >70 ka. According tothesestratigraphicconstraints, the IIandIIIordersdeveloped betweenabout105and develop onlybetweenabout130and105ka,whereas Interglacial. In particular, theIordershorelinecould that thethreeshorelinesarenotolderthanLast and Valensise, 1998). The conclusionsreachedare for LatePlaeistocenemarineterraces;Bordoni assuming asimilartrendofuplift(asusuallyassumed between distinctshorelinesaretaken intoaccount, al deposits relatedtoeachshoreline(Fig.4;Lucchi relationships betweenvolcanic productsandmarine shorelines areconstrainedbythestratigraphical The chronologicalintervals offormationthefossil correlation withmarineoxygenisotopestages(MIS). the cross-cuttingrelationships,andinferred basis oftheirchronologicalintervals offormation, The fossilshorelinesatLipariaredatedonthe younger shorelines. processes ortomarineerosionduringtheformationof unit. Thelowered sectorisfi surface cutslavas(A)relatedtothePaleolipari informal remnants ofaIorderterracedsurface(co Figure 19- At Bruca,four normalfaults(F)displacethe between theIordershoreline,andeustaticpeak Chappell the periodconsidered,byrevision suggestedby (det). IIorder(co ., 2003).Moreover, thecross-cuttingrelationships et al ed). 2 andco . (1996). A clearcorrelationappears 2 = littoralconglomerates;mp 1 = marineplatform): theterraced 3 conglomeratescontainpebbles 3 lled withdetritaldeposits = littoralconglomerates;mp 1 = cemented 2 = marine ed, for ed, 3 et = 125 ka(Lucchi rates ofvertical mobilityoccurringatLipariinthelast orders offossilshorelineshave beenusedtoestimate Chronological andheightdatarelative tothethree dated 100and81ka,respectively (Fig.20). the eustaticpeakswhichcorrespondtoMIS5cand5a, and IIIordershorelinescanbereliablyattributed to Quaternary marinestratigraphy(Vai, 1996). The II corresponds totheEutyrrhenianinMediterranean corresponding toMIS5e,dated124ka,which rate ofca.0.16mm/aisobtainedforthetimeintervals formation oftwo shorelines),aconstantmeanuplift from vertical displacement occurringbetweenthe the otherside,partialupliftratesareestimated(i.e. offset bynormalfaults (Figs.114 and19).If,on homogeneous heightdistribution isonlylocally parallel profi horizontal distribution oftheshorelinesinshore- Such aregular uplifttrend isconfi 0.34, and0.38mm/arespectively). calculated fortheI,II,andIIIordershorelines(0.31, is quiteconstantifweconsiderseparatelythevalues mm/a resultsforthelast125ka(Fig.21):thisrate A continuousandregular meanupliftrateof~0.34 of itsage,wecanestimatetherelevant upliftrates. displacement ofeachdatedshorelineasafunction each shorelineandpresenttime,byplottingthe a constantupliftbetweenthetimeofformation numeric andgraphicapproach(Fig.21):byassuming each shoreline. This estimate iscomputedwitha thus obtainingthevertical displacementwhichaffects eustatic sea-level changestotheirpresentelevation, we canestimatetherelative contribution ofglacio- of fossilshorelinescorrespondswithsea-level peaks, references therein).So,assumingthattheformation superimposed onarisingcoastline(Lajoie,1986,and record ofLate-Quaternarysea-level fl fact, afl Shackleton, 1986.Thecorrelationtakes intoaccountthe Figure 20-Correlationofthefossil shorelinesofLipari isotope stages,accordingtothecurve ofChappelland reconstructed intervalsofformation (ingrey).(From to theeustaticpeaksandassociatedmarineoxygen ight ofraisedfossilshorelinesisthegeologic les alongthewestcoastofLipari:this et al ., 1999;Calanchi Lucchi etal.,2003;modifi rmed bythealmost et al ., 2002b).In uctuations, 26-05-2004, 15:05:04 ed). GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

obtained for Panarea (variable, during the last 125 ka, between 0.69 and 1.56 mm/a; Lucchi et al., 1999). These results indicate a similar trend of continuous uplift for the whole central part of the Aeolian Arc (Lucchi et al., 2003). Crustal vertical movements of the volcanic edifi ces are interpreted as the result of interaction between punctuated eruptive, volcano- and neo-tectonic processes (transitory and active at local scale), and long-term sustained tectonic processes (slower, usually of lower magnitude and active at regional scale). In this view, the continuous and constant, long-term uplift trend occurring in the whole central-western Aeolian Arc during the Late-Quaternary should be explained by assuming a prevailing regional tectonic component. Regional Figure 21 - Numeric and graphic estimate of vertical crustal uplift at rates <1.21 mm/a (Bordoni and movements of the volcanic edifi ce of Lipari during Valensise, 1998) is known to affect the whole inner the last 125 ka. Models for the Islands of Filicudi, sector of the Calabrian Arc, and has done so since Salina and Panarea are also provided (Lucchi, 2000b). the Mid-Pleistocene. Here, crustal deformations are Legend: 1 = order of raised shorelines; 2 (E) = present connected with the subduction of the Ionian plate, elevation (metres asl) of the raised shorelines; 3 (e) = the main geodynamic process which controls the original elevation (m asl) of marine palaeo sea-level, geological evolution of the southern Tyrrhenian Sea corresponding to the formation of the raised shorelines (from the eustatic curve of Chappell and Shackleton, (Amato and Montone, 1997; Gvirtzman and Nur, 1986); 4 (U) = uplift (in meters) of the raised shorelines; 1999). These results indicate that vertical movements, 5 = ranges of uplift values, related to the fossil shorelines due to volcanic and volcano-tectonic processes, have (from column 4); 6 (aU) = average uplift values (from not been intense enough to condition the vertical column 5); 7 (t) = age (ka) of the raised shorelines ; 8 (R) mobility of all the volcanic edifi ces. Volcano- and neo- = mean uplift rate values in m/ka=mm/a (*= mean of the tectonic processes have been brought up to explain values obtained). (From Lucchi et al., 2003; modifi ed). the local occurrence of historical submergence trends 124-100 ka, and 100-81 ka (Tyrrhenian stage). This (5-10 mm/a in the last centuries) evident in some represents a further confi rmation of the notably places along the eastern coast of the Island of Lipari regular vertical behaviour of the volcanic edifi ce of (Calanchi et al., 2002b). On the other side, at Panarea Lipari. Evidence of rapid submergence during the last (located in the eastern Aeolian arc), where vertical few centuries, opposite to the long-term uplift trend, movements are continuous but not constant in time, has been observed only in some places on the east eruptive and volcano-tectonic processes seem to play coast of Lipari (Calanchi et al., 2002b). This process a signifi cant role in controlling the long-term coastal occur at rates considerably higher (ca. 10 mm/a) than tectonics (Lucchi et al., 2003). the relative sea-level rise estimated for the coasts of Sicily in the same period (Antonioli et al., 2002), and, General conclusions for this reason, it is explained with the occurrence of A threefold staircase of fossil shorelines, attributed to prominent neo- or volcano-tectonics (Calanchi et al., a Tyrrhenian age, has been defi ned along the emerged 2002b). Although such submergence movements are slopes of Lipari. They have been used as signifi cant likely to be responsible for the independent motion stratigraphic and morphotectonic markers. of discrete sectors of the volcanic edifi ce of Lipari, From a stratigraphic point of view, marine deposits P37 to P54 n° 5 - from Volume the long-term pattern which is put in evidence by (and their boundaries) allow main unconformities the coastal elevation changes, is one of persistent in the geological evolution of Lipari to be defi ned.

emergence (Calanchi et al., 2002b). The average Two fi rst order unconformities, UI and UII, have uplift rate estimated for the Island of Lipari (0.34 been introduced in the stratigraphy of Lipari, and

mm/a during the last 125 ka), is fully concordant then correlated at Panarea and Filicudi. UI and UII with rates similarly estimated for Filicudi and Salina must represent signifi cant stratigraphic constraints (0.31 and 0.36 mm/a, respectively; Lucchi, 2000a, b) for the whole Aeolian archipelago. They allow main for the same period (Fig. 20), but it differs from that evolutionary stages to be uncovered. In particular, the

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa tectonic processes. mm/a), explained bytheprevalence ofregional continuous uplift(atanaverage rateofabout0.34 at leasttheLastInterglacial, theoccurrenceofa coastal elevation changes.Ithasinvolved, since during theLate-Quaternaryhasbeeninferredfrom crustal deformationofthevolcanic edifi From amorphotectonicpointofview, apatternof predominant. “ by prevalent volcanic activity, spacedoutbythe and “post- be describedasthreemainstages:“pre- geological evolution ofthe Aeolian archipelagomay enrichment displayedbyvolcanic productsfromother show thesameunusuallyhigh gradientofK- The chemicalcompositionofthelavas fromLipari along theNNW-SSE tectonicalignment. eruption ofviscouslava fl magmas producedstrongerexplosive activity and whereas youngerhigh-Kandesiticandrhyolitic strombolian falls anderuptionoflow viscositylavas, the E-Wfracturesystemandarecharacterizedby volcanic productsappeartobeassociatedwith The oldestandmoreprimitive basalt-andesite Figure 22-K younger volcanic cycles. activity; andrhyoliticmeltsbecameabundant inthe 63% SiO2)ischaracteristicofintermediatecycles of appearance ofandesitesandhigh-K(58- basaltic andbasaltic-andesiteincomposition; follows (fi from theIslandofLiparicanbesummarisedas The petrologicevolution ofthevolcanic products Petrology oftheproducts Crisci etal.,1991,modifi Tyrrhenian Tyrrhenian g. 22):theearliestrocksareprimarily ” stage,whenerosionalepisodesare 2 O vs.SiO ” stages,whicharecharacterized 2 diagramofLipariproducts(from ed). ows ordomes,primarly ce ofLipari Tyrrhenian ” melts. favoured complex mixingduringtheascentof of sourcematerialswithdifferent compositions of theisothermsandalmostcontemporaneousmelting and/or toactive subductionprocesses. The quickrise input, andrelatedtotheopeningof Tyrrhenian Sea melting, initiallycausedbyanincreaseinthethermal in thelateractivity. The petrogeneticmodelinvolves time, andthecrustalcomponentbecomesdominant of theRomanComagmaticprovince) increaseswith input fromthealkalinemantlecomponent(source to theearlyevolution ofthevolcanism inLipari; of Tyrrhenian tholeiites),isanimportantcontributor with time. The sub-alkalinemantlecomponent(source the system,but the relative proportionsappeartovary mantle end-membersarealmostalways presentin Esperanca etal.,1992).Meltsfromthecrustaland and/or crustally-derived materials(Criscietal.,1991; and theotheralkaline,inadditiontocrustalmelts two mantle-derived components,onesub-alkaline evolved over timebyacomplex interplaybetween suggest thatthegeochemistryofLiparivolcanism lavas andpyroclasts, andgeochemicalmodelling, macroscopic andmicroscopicheterogeneityinsome fi rhyolites thatistypicalofsomebimodalvolcanic marks acompositionalgapbetweenandesitesand islands inthearc. The scarcityofdaciticcompositions elds. Geochemicalandpetrographicevidence for Figure 23-Locationofstops. 26-05-2004, 15:05:10 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

magmatic pyroclastics and lavas is exposed. The tuff- ring is covered by the “U Mazzuni2”scoria cone.

Stop 2.2: Locality: From Spiaggia della Papisca, to Punta delle Rocche Rosse. Description: Post-Tyrrhenian volcanics (11-1.3 ka). We will describe the stratigraphical relationships between different superimposed orders of rhyolitic domes and related pyroclastics. The internal structures (foliation and rampart structures), of the famous Rocche Rosse obsidian lava fl ow will be observed. Figure 24 - Shore-parallel vertical profi le of the eastern sector of Monterosa, eastern Lipari, where a natural stratigraphic section of the Monterosa lithosome is visible. In the basal portion of the cliff, a cross section of the Sciarra di Monterosa tuff ring occurs: the tuff ring is made up of hydromagmatic (sc1a) and scoriaceous pyroclastics (sc1b), and is capped by massive lavas (sc2). In the middle portion, scorias and lavas of the Pignataro di Fuori formation (pf) lie on a well-developed subaerial erosion surface, which cuts the remnants of the Sciarra di Monterosa formation. The stratigraphic succession of the Monterosa lithosome, is closed by scoriaceous pyroclastics and lavas of the Monterosa formation (mo1 and mo2). At the top of the cliff, a thin layer of Brown Tuffs (pi=Pianoconte formation) occurs. Stop 2.1: Locality: Monterosa Description: Pre-Tyrrhenian volcanics. Cross-section of the “Sciarra di Monterosa” tuff-ring, where the transition from hydromagmatic pyroclastics, to

Figure 26 - Shore-parallel vertical profi le near Bruca (central western sector of the island), where a natural stratigraphic section is exposed: the cross-cutting relationships between the three orders of fossil shorelines and main unconformities are particularly visible.

UI, UII = I order unconformities; L2 – L3 = II order unconformities; lb - lb = III order unconformities. (From

Tranne et al., 2002; modifi ed). P37 to P54 n° 5 - from Volume Figure 25 - Shore-parallel vertical profi le between Stop 2.3.: Spiaggia della Papesca and Capo Rosso (eastern Lipari), where a natural stratigraphic section is shown. The Locality: From Punta del Legno Nero to Punta le rhyolitic endogenous dome of the Capo Rosso formation Grotticelle. (cr), is capped by the pumiceous pyroclastics of the Description: Pre-Tyrrhenian volcanics (<125 ka) Vallone del Gabellotto (vg), and Sciarra dell’Arena and Tyrrhenian volcanics and marine deposits (125- formations (sa2). These stratigraphic relationships make 81 ka). The pre-Tyrrhenian units show the typical evident the II order unconformity L4 and the III order features of strombolian and hawaiian eruptive unconformity lg. (From Lucchi et al., 2004).

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa dome isclearlyvisible. At PuntaS.Giuseppe,apitcraterwithresurgent (foliation andrampartstructures)arevisible. structures ofrhyoliticendogenousdomes exposed. Along thissectionthetypicalinternal a spectacularnaturalgeologicalcross-sectionis particularly at“ScoglierasottoilMonte”,where domes andrelatedpyroclastics willbeobserved, different superimposedordersofrhyolitic ka). The stratigraphical relationshipsbetween Description Locality: Stop 2.4: Lucchi etal.,2004). “Lesser Brown Tuffs” (pi=Pianoconteformation). (From with pyroclasticlayersofexoticprovenance, known as recurrent lavicdomesandpyroclasticsareinterbedded to thecorrespondingexplosive phases(pe2,fa1,gi1).The associated withthepumiceouspyroclasticlayersrelating phase; fa2=IIgi2IIIphase).Thedomesare endogenous domeeffusion arehighlighted(pe1=I relationships between thethreefi section isshown. Inparticular, thestratigraphic western coastofLipari,whereanaturalstratigraphic Figure 27-Shore-parallelvertical profi (81-13 ka). covered bypost-Tyrrhenian pyroclastic successions of ancientshorelines. These depositsareuniformly marine deposits,attributed tothree different orders to M.ChiricaandM.S.Angelostratocones) hydromagmatic pyroclastics andlavas (related by complex stratigraphicalrelationshipsbetween style. The Tyrrhenian depositsarecharacterized deposits whichcharacterizedtheyoungervolcanic depositional facies, andfacies evolution, ofthe The thirddaywillbedevoted toillustratingthe Lipari From Valle MuriatoLipari. : Post-Tyrrhenian volcanics (81-13 DAY 3 DAY 3 rst phasesofrhyolitic le alongthesouth- 0.5 km of densemagmaeruptedwas estimatedatcloseto materials (Sheridanetal.,1987). The totalvolume out. Lipari, wheretheyoungestvolcanic productscrop coast oftheisland,toreachnorthernsector we willtake theroadwhichcrosseseastern deposits oftheMt.Guardiasequence;afterwards, domes structuresandtheproximalpyroclastic surge leaving Liparitown eastwards, tolookoutatthe stratigraphy oftheIslandLipari 3.25x10 The volume oferuptedproductswas estimatedtobe 29). morphological barriertothesurge dispersal(Fig. Mt. St. Angelo (nearly600mhigh)actingasa The depositsaredispersedtothenorth,with viscous lava domepluggedthevent. frequency untiltheendoferuption,whena and wetfi from meterstotensofcentimeters(fi fall deposits,andsurge bedswithwave-lengths breccias, whichareoverlain byaseriesoflapilli of theisland. The initialdepositsarelithic-rich the vent islocated,to<1minthenorthernpart more than50mjustoutofMonteGuardia,where cover LipariIsland,rangingintotalthicknessfrom +/- 200yearsago(Criscietal.,1981). The deposits fl pyroclastic depositsthatliebetweenbrown ash- An eruptionofshortdurationproducedthick The MonteGuardialithosome The juvenile fraction:macroscopic description domes. Figure 28-Low-angle cross-stratifi wet anddrysurgesoftheMt.Guardiasequence. ow tuffs, datedat22,600+/- 300and16,800 3 , ofwhichaboutahalfwas emplacedaslava 8 m ne laminatedsurge bedsincreasein 3 oflava, and4.75x10 cation intheupper 8 m 3 ofpyroclastic . We willbe g. 28).Dry 18-06-2004, 14:36:53 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

The dark grey clasts, the banded clasts and the enclaves are most abundant at the bottom of the sequence; upwards, their abundance decreases and the grey clasts become lighter and lighter in colour. At the top of the coarse-grained fall deposits, 85 vol%

Figure 29 - Simplifi ed geological map of Mt. Guardia products. From De Rosa et al., 2003 modifi ed. and vertical variations in the deposits The pyroclastic deposits are mainly composed of juvenile glassy fragments, showing a wide variability in colour and texture. De Rosa et al. (1993b) distinguished three main classes of juvenile fragments (white, grey, and Figure 30 - a) and d): White pumice with tabular shape streaky) (Fig.30). The white fragments (Fig. 30a,d) and elongated vesicles (bar =1cm) .b) and e): Grey pumice, rounded, poorly vesicular and crystal rich are mostly highly vesicular, elongated, «woody» (bar=1cm). C) and f) Banded pumice characterized by pumice with low crystal content. Unaltered mafi c enclaves. From De Rosa et al., 2003. obsidian-like clasts occur, showing the same mineralogy of white pumice. The dense clasts of the juvenile fraction is made up of white juvenile may originate during interaction of magma with components, and the remainder, of very light grey external water, since a hydromagmatic mechanism clasts (Fig. 31). of fragmentation was operative during the Monte Microthermometry on melt inclusions and feldspar Guardia eruption (Crisci et al., 1981; De Rosa, geothermometry (Wen and Nekvasil, 1994) 1999). Also, the obsidians may derive from the indicates a temperature of crystallization of around disruption of the chilled top of the magma column 760°C for the Monte Guardia rhyolite. The mineral in the conduit, formed in the time between the association and the presence of bivalent Europium

explosive pulses (Crisci et al., 1981). This latter indicate crystallization in conditions of low fO2.

mechanism may account for the high abundance of The pre-eruptive content in dissolved H2O is obsidian clasts in some beds. around 5 wt%, and was determined by FTIR on melt The grey pumice clasts are round-shaped, mildly inclusions and by the plagioclase-melt equilibrium vesicular, and with spherical vesicles (Fig. 30b),e). (Housh and Luhr, 1991), and is in accordance with P37 to P54 n° 5 - from Volume They display a large variation in colour within the presence of unrimmed hornblende (Rutherford individual samples and between samples; as a general and Devine, 1988). Dissolved chlorine is about

rule, the darker the colour, the more abundant the 3000 ppm, while CO2 and S are absent in the melt. mafi c phenocrysts in the pumice. These data indicate a P of crystallization of at least Streaky pumices show grey to dark grey bands 200 MPa, or 6-8 km of depth. The data collected on alternating with white bands (Fig. 30c,f). Grey and the older Lipari rhyolites (42 ky) indicate the same banded clasts often contain brown rounded enclaves, conditions (Gioncada et al., 2003). The described a few cm in size at most. pre-eruptive conditions characterize both the

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa the exhaustion ofthemafi the rhyoliticmagmafractionwhichtookplacewith The increaseinviscosity, duetotheincreaseof by thepulsatingcharacterofexplosive phase. the eruption(Woods andKoyaguchi, 1995),and rather low masseruptionrate at thebeginning of loss duringascentmayhave beenfavoured bythe in thecaseofMonteGuardiaeruption.Gas factor ontheshiftfromexplosive toeffusive style and Allegre 1991),mayhave beenthegoverning magma intheconduit(Eichelberger, 1995;Jaupart magmas. Syn-eruptive degassing duringtherisingof main factor controllingtheeruptive styleofrhyolitic eruptive volatile contentdoesnotrepresentherea fragmentation mode,andeffusively. Thus, thepre- explosively, withamagmaticandanhydromagmatic H km), andthatthey hadcloseto5wt%dissolved magmatic reservoirs locatedatmediumdepth(6-8 rhyolites eruptedatsouthernLipariascendedfrom De Rosaetal.(1993b)suggestthatthedifferent fragmentation Factors controlling thepossibilityof the effusive one. explosive activity and,atleastintheinitialphase, From DeRosaetal.,2003. the sequenceofdepositsMonteGuardiaeruption. Figure 31- Variation ofthemixingproportions through 2 O. These features characterizemagmaserupted c mixed magma,was a Rosa etal.,2003c). column, inbetweensuccessive explosive pulses(De devolatilization andcoolingatthetopofmagma degassing magmaalongtheconduitwalls, andfrom obsidian clastsinthedepositscomefrom emptying ofthechambertookeffect. The abundant eruption rate,beforetheeffect oftheprogressive main factor indeterminingtherapiddecreaseof distance inthetractioncarpet. These materialsform ballistic fall population,oraresweptalongforashort settle toitsbase. There they eitherremainin place asa coarser particlesthatfall intoamoving surge cloud They assumethat duringhighvelocity transport,the model fortheemplacementofsurge bedsofthistype. ash layer, Frazzettaetal.(1989),have proposedanew pumice, thatgradesupwards intoanoverlying fi of bedsetswhichcontainacoarselower layer of a typicalfeaturesofthesurge depositsisthepresence dune-forms, withminorantidunestructures.Because The wavy bedsshow symmetricalandasymmetrical of fall andlarge-scale wavy bedformsofsurge origin. clasts (<5%). The sequence isformedbyanalternation obsidian clasts(<5%),andgeothermalalteredlava The depositsconsistofaphyric,rhyoliticpumices, excellent sections(Fig.30and32). Bianco areawhereextensive quarryinghasexposed outcrops lieinGabellottogorge andintheFiume contour onthenorthernpartofisland. The best deposits cover anareaofabout11km (Pomiciazzo lava; BigazzieBonadonna,1973). The and 8.6karespectively byfi fl al. (1986),andthelarge endogenousobsidian-rich the Gabellotto-FiumeBiancotephraofCorteseet The Gabellottolithosomeincludesthedepositsof The Vallone delGabellottolithosome owing domeofPomiciazzoformation,datedat11.4 Figure 32-Panoramic viewoftheGabellottoproductsin ssion-track determinations the Gabellottogorge. 2 withinthe2m 26-05-2004, 15:05:29 ne GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

the coarse part of the bedset, while the fi ner material is partly covered, and partially destroyed, by the effusion either transported above the traction carpet, or trapped of the obsidian lava fl ow of Rocche Rosse that ended between the larger stationary pumice clasts. A large the eruptive activity. Dellino and La Volpe (1995, portion of the deposit has been moved by saltation 1996) identifi ed four main lithofacies, representing or intermittent saltation. As the cloud slows, either 90% of the erupted products (Fig. 34). with time, distance, or due to local fl ow perturbations, These lithofacies include well-sorted pumice lapilli progressively smaller clasts settle into the traction carpet, where they are deposited together with the rolling coarse pumice. At the waning stages of the passage of a surge, and at more distal localities where the velocity is suffi ciently slow, most of the coarse pumice has been deposited, and clasts transported by saltation and suspension form the capping horizon of the bedsets. A paired bedset thus represents the passage of a single surge cloud. The Mt. Pilato lithosome The Mt. Pilato lithosome mainly includes the pumiceous succession which builds the cone of Mt. Pilato and the Fossa delle Rocche Rosse formation. Historical reports indicate the date of AD 729 for the latest volcanic activity (Cortese et al., 1986). The internal structure of the cone is clearly visible in the Campo Bianco and Acquacalda quarries (Fig. 33). The deposits mainly consist of pumiceous lapilli

Figure 34 - Schematic composite stratigraphic section of Mt. Pilato-Rocche Rosse sequence (from Dellino and La Volpe, 1995). Figure 33 - The internal structure of the Monte Pilato pumice cone (Campo Bianco quarry). graded beds of fall origin (lithofacies 1), poorly- sorted massive beds of fl ow origin (lithofacies 2), and bomb layers, alternating with pumice lapilli plane-parallel surge beds (lithofacies 3), and fi ne ash layers with abundant ash matrix in the middle part deposits with abundant accretionary lapilli (lithofacies of the sequence. The top part consists of fi ne ash 4). Field and laboratory data lead to the suggestion Volume n° 5 - from P37 to P54 n° 5 - from Volume layers rich in accretionary lapilli, which alternate that during the Monte Pilato-Rocche Rosse eruptions, with rare pumice lapilli and bomb layers. Outside magmatic and hydromagmatic mechanisms occurred, the cone structure, only the deposits that form this frequently at the same time, and that both fallout and upper portion of the sequence crop out. In the inner fl ow emplacement mechanisms were operative. crater zone, there is an erosional contact between the Monte Pilato sequence, and the deposits of Fossa General considerations delle Rocche Rosse formation, which consists of a 20 Rhyolites of Vallone Gabellotto, and Mt. Pilato m thick coarse grained pumice strata, alternating with lithosomes, lack any phenocrysts in equilibrium ash layers formed a small cone that subsequently was with the silicic glass, so we have no indications

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa During ascent,H The S.Nicoladomeisasmallasymmetrical-type dome (Fig.36). mingling structuresandtextures oftheS.Nicola Mt. Guardiapyroclastic sequence.Close-upofthe and Mt.Giardinarhyoliticdomes,aswellofthe Description: Locality: NearS.Anna Stop 3.1: Figure 35-Locationofstops dilute theH inducing crystalresorbing.Meltingofcrystalswill become lower thanthetemperatureofmagma, ~ 0.5°C/MPa (JohannesandHoltz,1996),may the temperatureofliquiduswilldecreaseatarate an undersaturatedmagmaascendsandPdecreases, (Blundy andCashman,2001). They argue that,as to water-undersaturated isothermaldecompression heating byamafi the absenceofphenocrystscouldberelated,notto hypothesis, DeRosaetal.(2003c)suggestthat on theirpre-eruptive conditions. As aworking degassing willprovokes themigrationof T aphyric rhyoliticproducts. This maybewhathappenedinthecaseofLipari silicic melts,whereitmaybekineticallyimpeded. result incrystallization,except forhighlyviscous to highervalues. The consequentundercoolingwill 2

O dissolved, postponingH Panoramic view oftheMt.Guardia c magmathatisnever erupted,but 2 O-saturation willbeattained,and 2 O saturation. liquidus

1993). enclaves oflatiticcomposition(Gioncadaetal., a sub-aphyricrhyolitecontainingvariously deformed along aNNW-SSE direction. This domeconsistsof lithosome (between23.5and16.8ka),isaligned domes whichbelongtothePuntaS.Giuseppe northermost extrusion ofthreeendogenouslava “low lava dome”ofBlake, 1990).Itrepresentsthe sector ofLipari(the40mhighand200mwide, dome structure,whichoutcropsinthesoutheastern Pilato pumiceousdepositsisexposed inthisquarry. Description: Locality: Stop 3.4: amplitude of25m. of thesequence,wherewave structureshave an origin. The surge sequenceprevails intheupperpart pumice fall strata alternatewithlayersofsurge Gabellotto formation.Inthelower partofthesection gorge,, wewillobserve thesequenceof Vallone deposits oftheLamicenter. Onthewall ofthe Description: Locality: Stop 3.3: upper dryandwetsurge deposits ofthesequence. correlate themeasuredsections.2) A close-upofthe grained beds,thathave beenusedaskey markers to grained beds,whicharealternatedwithdistinctfi includes: 1) A panoramicview ofthelowest coarse- proximal area,whereitisabout25mthick. The stop exposure ofmosttheMt.Guardiasequenceina Description: Locality: ValloneMuria Stop 3.2: Figure 36-Mafi Acquacalda quarry Near Lamivillage Close-upofthespatterpumiceous The valley provides anexcellent A hundredmeter-thick sequenceofMt. c enclaves oflatiticcompositionincluded in therhyoliticlavadomeofS.Nicola. 18-06-2004, 14:37:32 ne- GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

The strata are mainly meter-thick layers of pumice volcanic structures (Fig. 37): the South Vulcano bomb and ash, with scattered lithic clasts, which centers, the Lentia complex, the Fossa cone and alternate with decimeter-thick layers of pumice lapilli. Vulcanello. A signifi cant part of the sequence can be interpreted as Two caldera-type structures are present in the central due to secondary volcaniclasti processes. part of the island. The Caldera del Piano was formed (98 ka) by the collapse of the summit part of South Stop 3.5: Vulcano. This depression was infi lled partially by Locality: Fiume Bianco quarry compound lavas, and successively by pyroclastic Description: Close-up of the Vallone Gabellotto deposits related to volcanic centers mostly located sequence. The sequence shows wave-like bedforms inside the caldera and along its rim. The present with minor planar bedforms. Several of these layers caldera fl oor has a mean altitude of 350m a.s.l., and form paired bedsets, with a coarse pumiceous lower the caldera rim reaches a maximum height of 500m part that grades upwards into overlying fi ne ash a.s.l.. The younger Caldera della Fossa depression layers. was formed by large collapses affecting the northern sector of the Caldera del Piano and the Lentia volcanic DAY 4 complex during the last 50ka (Gioncada and Sbrana, Vulcano 1991; Voltaggio. M. 1993 pers. comm.). The present fl oor of the depression has an altitude ranging from 7m (northern sector) to 172m (southern sector). The Island of Vulcano is an active volcano of the The La Fossa cone, which is the active volcanic Aeolian archipelago. edifi ce of the island, as made evident by the intense The whole subaereal part of the island was built fumarolic emission, has developed inside the Caldera up during the last 120ka, and consists of four main della Fossa depression. The subaereal part of the cone was formed in the last 6ka, and rests on the compound lava fl ows of La Roia (14ka). The Vulcanello peninsula was formed between the 2nd century B.C. and the 16th century A.D. in the northern sector of the island. The last eruptions of Vulcano took place at the La Fossa cone in 1888-90 (and these were of the “vulcanian” type of eruptions). STRATIGRAPHY AND VOLCANOLOGY OF THE ACTIVE CONE OF Volume n° 5 - from P37 to P54 n° 5 - from Volume

Figure 38 - Photograph showing the La Fossa cone and Figure 37 - Geological sketch map of Vulcano Island, the walls of the La Fossa caldera of Vulcano. showing the distribution of the volcanic units erupted during the six main periods of activity (modifi ed after LA FOSSA De Astis, 1995). The top inset shows the location of the Aeolian arcipelago in the Tyrrhenian Sea; the bottom The stratigraphy of La Fossa di Vulcano has been inset represents a structural sketch map of the Vulcano- studied at the centimeter scale, and beds due to each Lipari-Salina Islands (modifi ed after Ventura, 1994) of the eruptive events of the volcanic history have

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa or partlymodifi successive eruptive activities have onlyemphasized of themainstructurevolcanic edifi activity ofLaFossa, andhasleadtotheedifi of theeruptedmaterialwholeeruptive area isshown infi The PunteNereSuccession,whosedepositsdispersal characterized bythreeeruptions. 5), theCratere Attuale Succession,whichhasbeen Succession, whichismadeupof2eruptions;and has beenformedby3eruptions;4) The Commenda comprises 3eruptions;3)thePalizzi Succession,which 3 eruptions;2)the Tufi are: 1)thePunteNereSuccession,whichencompasses From theoldertoyoungeronethesefi of LaFossa (Fig.39). eruptions, have beendistinguishedinthestratigraphy scheme, fi eruptions andquiescenceperiods.Following this these subdivisions, andtodelineatethetimingof Geochronological datahave beenusedtosupport and tothegroupingoferuptionsinto“Successions”. lead totheattribution ofbedstoindividual eruptions, The discontinuitiesidentifi been distinguished(DellinoandLa Volpe, 1997). products ofLaFossa di Vulcano. (modifi Figure 39-Schematic stratigraphicsectionoftheeruptive and la Volpe, 1997) ve successions,whichcompriseatotalof14 ed theconeform. This Succession g 38a,representsthemostpart Varicolori Succession,which ed inthestratigraphyhave ed afterDellino ve successions c. The ce. cation accumulation, thevolcanic conereachesaheight this unithave aninclinationof30°andduetotheir with hydromagmaticashlayers. The depositsof in decimetertometer-thick layers,whichalternate lapilli andblockdeposits,duetoballisticfallout, angle. The intermediateunitiscomposedofdense formed a150meter-high tuff ringwitha15°slope years BP, ispresent. The depositsofthisunithave scoriae, witharadiometricageof5300+2200/-1100 of thesedeposits,ametriclayerlatiticwelded of theeruptive historyofLaFossa. Inthetoppart of ashprevail. They arethemost disperseddeposits In thelower unit,latitichydromagmaticdrydeposits different dispersalareasoftheproducts. lithological characteristicsofthedeposits,andin has beensubdivided intothreeunitsthatdiffer inthe Figure 40-Mapsrepresentingthedispersalareaof Vulcano. a=PunteNereSuccession;b=Tufi eruptive productsofthe5SuccessionsLaFossa di Succession; c=Palazzi Succession;d=Commenda (modifi Succession; e=Cratere Attuale Succession ed afterDellinoandla Volpe, 1997). Varicolori 26-05-2004, 15:05:50 GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

of about 250 m. The upper unit is represented by Cotte rhyolitic lava fl ow, which was effused in 1739 a trachitic lava fl ow, with a radiometric age of AD on the eastern sector of the cone, and closes the 3800+2200/-1100 years BP. unit. The deposits of this unit are dispersed around The second succession, whose deposits dispersal the cone. area is shown in Fig 40b, Tufi Varicolori di La The post 1739 unit is made up of an alternation of Fossa, has been subdivided into three units that hydromagmatic ash layers and dense lapilli and blocks are separated by erosional surfaces. These three deposits due to ballistic fallout. It has been formed by units have similar lithological characteristics and periodic and intermittent eruptive activity. The eruption dispersal area. The lower and upper units are made up chronicles reports that in the period 1739 – 1888, mainly of hydromagmatic ash deposits, whereas the frequent eruptive events occurred. The dense lapilli intermediate one is composed of a sequence of latitic and block deposits have a dispersal area restricted to and shoshonitic ash layers, with some intercalations the volcanic edifi ce, whereas isolated outcrops of some of shoshonitic layers of vesiculated lapilli and layers of hydromagmatic ash have been found outside bombs due to ballistic fallout. One of the latter has a the cone, on the Caruggio area, and also outside the rim radiometric age of 2900+/-350 years BP. of the La Fossa caldera, both at the Lentia complex, and The third succession, whose deposits dispersal area at the base of Monte Saraceno. The 1888-90 eruption is shown in Fig. 40c, Palizzi, has been subdivided unit is formed by a sequence of dense lapilli and blocks into three units based on the occurrence of erosive deposits, with intercalations of hydromagmatic ash surfaces. The lower complex unit is made up of layers. A layer of vesiculated lapilli and bombs of a sequence of hydromagmatic ash deposits, with latitic composition is also present within this sequence. two intercalations of vesiculated lapilli and bombs Dense clasts of lapilli and blocks with scattered bread due to ballistic fallout. The fi rst one has a rhyolitic crust bombs, represent the products of the last eruptive composition, the second, trachitic. One of the ash beds has a radiometric age of 2100+/- 300 BP. The intermediate unit consists of a lava fl ow that surrounds the eruptive vent, and has fl owed only a few hundred meters from the emission crater. The upper complex unit, formed about 1500 years BP, is made up of a sequence of hydromagmatic ash deposits, and by a trachitic lava fl ow that extends southwards down to the cone base. The fourth succession, the Commenda succession, whose deposits dispersal area is shown in Fig. 40d, was formed about 1250 years BP. It is made up of a breccia unit at its base. It is composed of a metric layer of dense lapilli and blocks set in an ash matrix, by a dense lapilli and blocks layer due to ballistic fallout and by an ash layer. These deposits are mainly composed of lithic clasts showing a high degree of hydrothermal alteration. After a brief period of rest, the varicolori ash unit formed. It is mainly composed of a densely- stratifi ed sequence of latitic hydromagmatic ash deposits. They are the most widespread deposits of the whole Commenda succession. P37 to P54 n° 5 - from Volume The fi fth succession, whose deposits dispersal area is shown in Fig. 40e, the Cratere attuale one, has been subdivided into three units, taking into consideration both stratigraphic features and eruptions chronicles. Figure 41 - a= Photograph showing a close-up view of The complex unit of Pietre Cotte is composed at the a dry surge bed of La Fossa di Vulcano; b= photograph base of latitic hydromagmatic ash deposits. A metric showing the contrasting lithological features of dry surge vesiculated lapilli and bombs deposit, due to ballistic (top) and wet surge (bottom), deposited at fallout of rhyolitic composition comes after the Pietre La Fossa di Vulcano.

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa In thedryones,depositionissimplyof the wetones(fi deposits. The drydepositsarecoarsergrainedthan refl vapor wassuperheated instead. This difference is transportation, forthewettype.Indrytype of asignifi The difference betweenthetwo isdueto the presence into two sub-types,dryandwet(fi These hydromagmaticashdepositsaredistinguished been alittledeeperintheconduit. amount oflithicclasts,thefragmentationlevel has and Tufi in theconduit.OnlyfordepositsofPunteNere Vulcano probablyoccurredatvery superfi the hydromagmaticfragmentationatLaFossa di volcano. Becauseofthescarcitylithicfragments, it fedgravity fl «low angle»eruptive cloud was thusformed,and out ofthevent, togetherwithgasesandvapors. A magma/water interaction,ashparticleswereexpelled the explosion andfragmentation,duetoeffective hydromagmatic eruptive processes. As theresultof dilute fl ash layersthatwereemplacedbyturbulent and layers ismadeupofcentimetertodecimeter-thick the mostrecurrentone,costitutingmorethat80%of and transportationdynamics. Among theselithofacies which representdepositsduetosimilarfragmentation La Fossa have beengroupedinto5lithofacies eachof structure, bedsofthewholestratigraphicsequence Using aschemebasedonthickness,grainsizeand Hydromagmatic depositsofLaFossa around LaFossa cone. crateric area,have arelatively large dispersionarea event. These clasts,uptoseveral metersbiginthe centimeter-thick wet surgebedsofLaFossa di Vulcano. Figure 42-Photographshowing aclose-upviewof ected inthestructuralandtextural featuresof Varicolori successions,whichshow alimited ows (surge). These depositsarerelatedto cant amountofcondensingwater during g. 43). ows thatexpanded radiallyfromthe g 41and42). cial levels cial In thewetones,depositionoccursbywater lamination (fi decimeter-thick layerswhichshow inclinedinternal tractional typeanddepositstypicallyoccuras Figure 44-GeneralviewofdrysurgebedsthePalizzi Figure 43-Grain-sizedistribution ofrepresentative dry g. 44). eruptions, showing alaminatedstructure surge (a)andwet surge(b)beds. and tractionalfeatures 26-05-2004, 15:06:01 . GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

condensation, and there is a consequent aggregation of fi ne ash at the fl ow base. Deposits are centimeter- thick depositional units, with minor tractional structures, and typically show features such as accretionary lapilli, vesiculated tuffs, and plastic deformations (fi g. 45), which refl ect the presence of liquid water at the onset of deposition. To make a hard and fast distinction between the

Figure 46 - Comparison between characteristic particles from experiments with those from natural deposits of La Fossa di Vulcano, using scanning electron microscope images. a, Blocky and equant-shaped particle from ‘dry’ explosion Figure 45 - General view of wet surge beds of the experiment (series I) with stepped surfaces and etches Commenda eruption, showing plastic type deformations on the surface. b, Analogue particle from a ‘dry’‘wet’ induced by ballistic impacts. explosion experiment (series II,) showing addition branching quench-crack structures. d, Analogue particle structural and textural features of these two types from a ‘wet’ phreatomagmatic surge deposit of La Fossa. of deposits is to refer only to the emplacement experiments of the dry type (series I) typically mechanism. In fact, it must be remembered that a show blocky, equant shapes, and “stepped” glass continuous spectrum between the two types exists; surfaces by “mechanical” etching (fig. 46a). The inside the deposit sequences where the dry type same type of particles are present in the fine ash prevail, some layers of the wet type are present too, fraction of natural dry and wet deposits (fig. and, conversely, in the wet sequences, some dry layers are always intercalated. 46b). These clasts obviously result from a brittle process, i.e. the deformation rate acting on the Fragmentation mechanisms magma was so high, that liquid relaxation of the The phreatomagmatic activity of La Fossa was stresses could not work. These particles have been experimentally simulated with the use of the TEE- identified as the fingerprints of thermohydraulic II Experiment at the Physikalisch Vulkanologisches explosion processes, representing the most Labor at Wuerzburg University (Buttner et al, intensive type of magma/water interaction. Fine 1999). A suitable magma simulant was generated ash fragments from explosion experiments of the by remelting the actual volcanic rock. Different wet type (series II), show similar features, plus, experimental series were performed, simulating on a significant number of fragments, the glass both wet and dry conditions, and in all cases 0.4 surfaces are covered by a branching network of kg of melt at magmatic temperatures was prepared quench cracks (Figure 46c). These cracks must Volume n° 5 - from P37 to P54 n° 5 - from Volume under atmospheric conditions and controlled have formed immediately after fragmentation, oxygen fugacity in cylindrical crucibles. The due to sudden cooling. These kind of clasts are experimentally produced wet and dry pyroclasts also found in natural phreatomagmatic deposits were then analyzed and compared to their natural (Figure 46d), and in significantly higher amounts analogues. in wet surge deposits compared to the dry ones. The size fraction containing the relevant information These quenching structures, that were never found on the explosive magma/water interaction processes in the products of the dry experiments (series I), is the fi ne ash fraction. are related to the fast passage of just fragmented Fine ash clasts derived from explosion particles through a domain of liquid water. This

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa information wecangainonthissubject,byusing and notthedeposit“asis”,let’s seewhatkindof events, thedynamicsoffl Since forthehazardassessmentofthesetype different. analogous, onlytheemplacementmodelis the flows ofthewetanddry typesareindeed movement. The dynamicsoftransportation particles show avery highresistancetotractional just-deposited material,becausefine, adhesive to inducevery significant tractionaleffects onthe a turbulent anddilutedflow, but willnotbeable effect thatoccursatthebase,continuestomove as the flow, whichdoesnotexperience theviscous of thesetypedeposits. The overlying partof the fine particles,toformthepeculiarstructures abundant, andiseffectively cooledandaggregates the viscousforcesprevail, thevapor ismore the flow (incontactwiththesubstratum)where In thecaseofwettype,inbasalportion stages, dropssignifi and they aredepositedonlywhenthefl particles arealways heldinaturbulent suspension, Actually, inthecaseofdry typeoffl hazardous itis. and toxicityofthefl diluted fl on theroofsofhouses,incaseturbulent and where thedangerisrelatedtoloadofdeposit eruptive events. As opposedtothefallout deposits, represents thedangertohumanlifeofthesetype “as is”,but thefl due toturbulent and dilutedfl What isvery importantinthestudyofashdeposits Transportation anddepositionmechanisms present duringtheeruption. in thiscaseamoderateamountofexcess water was surge depositsofLaFossa thusindicates,thatalso these kindofmarker particlesintheso-calleddry eruptions. The occurrenceofaminoramount found inpyroclastic depositsofancientandrecent explosive phreatomagmaticvolcanism tobe wet conditions,areactuallytherecordof by explosive magma/water interactionunder observed onthesurfaces ofashgrainsproduced The quenchcrackstructures,exclusively dry phreatomagmaticdepositsofLaFossa. and they aremorefrequentinthewetthan form whenexcess water ispresentintheconduit, in aneffective chilling.Particles ofthiskindonly mechanism resultsinahighcoolingrateandthus ows, itisthevelocity, thickness,temperature, ow thatproducesit.Itisthefl cantly invelocity. ow whichdetermineshow ows, isnotthedeposit ow areimportant ow, initsfi ows, thefi ow that nal ne We canindeedaffi morphological barrierofthecaldera. to amassive, highstructurebeneaththesteep from alaminatedstructure,atthebaseofcone, Monte Rosso(Fig.47),thedepositslaterallypass Along theprofi the fl the CalderadilaFossa, give importantinsightsinto Fossa cone,andwhichcrosstheobstaclebarrierof textural featuresalongtwo directionsthatformthe The following lateralvariations ofstructuraland di Vulcano. the structuralfeaturesofdepositsatLaFossa thickness notsignifi material. Therefore, even ifwedonotfi as toproducetractionalfeaturesonthedeposited that thevelocity was high enough(tensofm/sec) Piano di Alighieri, thefl decreases invelocity, andwecanconcludethatat obstacle, andthereforedidnotexperience sudden a thicknesshighinexcess ofthemorphological This meansthatthefl structure. Alighieri, thedepositsalways show alaminated the profi In thesecondcase(Fig.48),whichrepresents particles, was extinguished. suddenly depositedandthefl a strongdeceleration,andthesolidmaterialwas the morphologicalobstacle,itthereforeexperienced successively eroded),thefl outcrops over Pianodi Alighieri (becausethey were of particles,hastravelled even furthersouth,asfar as Figure 47-Depositionalbehaviourofsurgedepositsthat ow characteristics. laterally passfromalaminatedtomassive structure le thatgoesfromthecratertoPianodi which causesasteeptopographicaljump le thatgoesfromthecraterto catively inexcess oftheheight rm thatbecausethefl ow had,alongthatdirection, ow was stillexpanded, and ow, withitsresidualload ow, losingitsloadof nd signifi ow hada 26-05-2004, 15:06:13 cant . GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

that at the base of the cone, fl ows had a velocity in excess of 50 m/sec, and a thickness in the order of 280 meters. The part of the fl ow that surpassed the caldera barrier was about 90 meters thick, and had a velocity of about 30 m/sec. The distance the ash particles travelled in turbulent suspension before the fl ow was extinguished, was in the order of 1100 meters from Passo del Piano, which is the topographical opening from which fl ows have repeatedly overridden the caldera obstacle in the past. This distance is in agreement with the dispersal area of the loose ash that covers the Piano Area and has been attributed to the Fossa activity. The converging geological and sedimentological results demonstrate that the model proposed,even Figure 48 - Depositional behaviour of surge deposits that if it is approximate, adequately describes the maintain a laminated structure also when surpassing fl uidodynamics of the turbulent and diluted fl ows a topographic barrier. of ash, and that this model might help to predictthe the Piano Area. turn of events at La Fossa di Vulcano in any future This situation occurs for the deposits of the Punte eruption. Nere, Palizzi, and Commenda succession, where, as a function of the local height and morphology of the Hazard assessment caldera rim, the deposits in some locations suddenly The sedimentological model used for the pass from laminated to massive structures, whereas reconstruction of the fluid-dynamic characteristics in other locations they remain always laminated, of the flows, takes into consideration deposits, again in correspondence to the caldera rim and its from a single eruptive event which emits about fl anks. 1 million cubic meters of material out of the Concerning the deposits of the post 1739 unit of vent. For these type of events, an approximate the Cratere attuale succession, it is not possible calculation of the water needed to produce the continuously to follow the lateral structural hydromagmatic explosion, is in the order of tens evolution, but since the depositional units found of thousands of cubic meters. This estimation at the base of Monte Saraceno have tractional comes from calculations based on experimental structures, it is possible to suggest for these data. events as well, that the flows have surpassed the The elaboration of a deterministic model of the caldera rim and have expanded throughout the hazard related to the expected event, will be possible Piano Area. only on the basis of a detailed knowledge of the Using this evidence as a starting point, the loose ash hydrogeological system of La Fossa di Vulcano, that covers the Piano area has been analyzed, and it which will allow the exact determination of the has been possible to attribute it to La Fossa activity, amount of water available in the conduit system, in particular to the Palizzi eruptions (Dellino and La at the onset of the eruption. The forecast of such an Volpe, 2000). event is related to the ability of geophysical and/or Based on this evidence, a sedimentological study geochemical methods to record the rate of ascent of has been carried out on the turbulent and diluted such volumes of magma in the superfi cial level of Volume n° 5 - from P37 to P54 n° 5 - from Volume fl ows, using the structural and textural features of the conduit. those deposits which, on showing lateral continuity, It is possible to give a probabilistic estimation of allowed the testing of results. the hazard related to the expected event, taking into Deposits from the Palizzi eruptions have been consideration the data obtained from both the eruptive chosen because it was possible to continuously scenario, and the sedimentological model. trace correlated layers from the base of the cone to In the hazard assessment, the eruptive events that over the La Fossa caldera rim. The results of the characterized the eruptions that occurred during application of the sedimentological model indicates and after the Palizzi succession, can be considered, since the previous ones had characteristics that seem

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa area, onland,whichisaffectedbythesefl effects inthezoneofPianodi Alighieri. The order of30m/sec,andmaintaintheirdestructive caldera rimwithmaximumvelocities, inthe fl life. These destructive power intermsoflosshuman cross thewhole Vulcanello area, withalltheir fl future eruption. With thisvelocity, andrelative that wehave toexpectat Vulcano Porto ina to theradialdispersalarea, thisisthevelocity a maximumvelocity inexcessof50m/sec.Due at thebaseofcone(inPalizzi area), had surmounted theLaFossa calderarim. The fl from thePalizzi succession,thefl In 50%oftheeruptionsthatoccurred, starting unlikely toberepeatedinthefuture. the zonewherethereisa100%probabilitythatfl impact inafutureeruption.Thedarkgreyarearepresents where thereisa75%probabilitythatfl eruption. Themediumgreyarearepresentsthezone 50% probabilitythatfl light greyarearepresentsthezonewherethereisa Figure 49-HazardmapofLaFossa of Vulcano. The have impactinafutureeruption. ow thicknessandconcentration,thefl ows willlikely surpass theLaFossa ows willhave impactinafuture ows willhave os have ows ows will ows ows will ows, is ows, ows, the maincone. we willtake atrailonthelefttoreachtopof located. ProceedingalongtheroadtoPiano, Vulcano, wheretheactive coneofFossa is The fourthdaywillbespentontheIslandof ground very slowly. disperse intheatmosphere,toeventually settleonthe immediately deposited,andtheupperonewill from theoverlying fl the rapiddecouplingofbasalandcoarserload, highly dilutedinorigin,afurtherdilutionproduces expansion downslope ofthefl of thesharphydraulicjumpthatcausessudden the hazardofexpected event isavoided, because to Gelso,isconsideredbesafe.Intheselocalities, The Gelsoarea,andtheroadthatgoesfromPiano chance ofhazardoccurring. represents suchakindofevent, andrepresents100% hazardous effects. The areaindarkgrey ofFig.20 base oftheconeLaFossa, withtheiraccompanying In the100%ofcasesfl occurring. magnitude andrepresentsa75%chanceofhazard medium grey inFig.49,envelopes theevents ofthis also crossthewhole Volcanello area. The areain area. Consideringaradialdispersal,thesefl high expansion, andalsotravel over theCaruggio fl In 75%oftheeruptions,thesekindevents have 50% ofhazard. colored inlightgrey onFig. 49,andrepresents a owed withavelocity oftensm/secandwitha ow. The basalpartwillbe ows have expanded over the Figure 50-Locationofstops. ow. Onthesefl 26-05-2004, 15:06:18 ows, ows GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

Stop 4.1: products of lower crustal fusion or of assimilation Locality: Gran Cratere rim plus fractional crystallization? Contrib. Mineral. Description: A panoramic view of the Caldera della Petrol., 97, 460-471. Fossa and of the surrounding volcanoes. Close-up Beccaluva L., Gabbianelli G., Lucchini F., Rossi observation of the 1888-90 products. P.L. and Savelli C. (1985) Petrology and K/Ar ages of volcanic dredged from the Aeolian seamounts: Stop 4.2: implications for geodynamic evolution of the Locality: Palizzi Southern Tyrrhenian basin. Earth Planet. Sci. Lett., Description: Close-up examination of the deposits 74, 187-208. of the Palizzi eruptions, which represent the highest Beccaluva L., Rossi P.L. and Serri G. (1982). magnitude of events expected in the future at Neogene to recent volcanism of the southern Vulcano. Facies analysis of some peculiar dry-surge Tyrrhenian-sicilian area: implications for the beds will be carried out. geodynamic evolution of the Calabrian Arc. Earth Evol. Sci., 3, 222-238. Stop 4.3: Bertagnini, A., Coltelli, M., Landi, P., Pompilio, M. and Rosi, M. (1999). Violent explosions yield new Locality: Lentia insights into dynamics of Stromboli volcano. EOS Description: This outcrop illustrates: 1) the 80, 635-636. downcurrent facies evolution of the Palizzi surges, Bigazzi G.& Bonadonna (1973). Fission track dating that are here mostly represented by fi ne-laminated of the obsidian of Lipari Island (Italy). Nature, 242, grey beds, that commonly show low-angle oblique 322-323. stratifi cation. 2),the erosional contact with the Blake, S, 1990. Viscoplastic models of lava lowermost deposits. domes. In Jonathan H. Fink (Ed.) Lava Flows and Domes, Emplacement Mechanisms and References cited Hazard Implications. Springer Verlag, Berlin. Allard, P., Aiuppa, A., Loyer, H., Carrot, F., pp 88-126. Gaudry, A., Pinte, G., Michel, A. and Dongarrà, Blundy, J., Cashman K. (2001) Magma ascent and G. (2000). Acid gas and metal emission rates crystallization at Mount St. Helens, 1980-1986 during long-lived basalt degassing at Stromboli Contributions to Mineralogy and Petrology 140: volcano. Geophysical Research Letters 27, 1207- 631-650. 1210. Bonaccorso A., Calvari S., Garfì G., Lodato L., Allard, P., Carbonnelle, J., Métrich, N., Loyer, H. Patanè D. (2003). Dynamics of the December and Zettwoog, P. (1994). Sulphur output and magma 2002 fl ank failure and tsunami at Stromboli degassing budget of Stromboli volcano. Nature 368, volcano inferred by volcanological and geophysical 326-330. observations. Geoph. Res. Lett., v.30, no.18, doi: Antonioli, F., Cremona, G., Immordino, F., 10.1029/2003GL017702. Puglisi, C., Romagnoli, C., Silenzi, S., Valpreda, Bonaccorso, A., Cardaci, C., Coltelli, M., Del Carlo, E., Verrubbi, V. (2002). New data on the Holocenic P., Falsaperla, S., Panucci, S., Pompilio, M. and sea level rise in NW Sicily (Central Mediterranean Villari, L. (1996). Annual report of the world volcanic Sea). Global and Planetary Change, 34/1-2, pp. eruptions in 1993, Stromboli. Bullettin of Volcanic 121-140. Eruptions 33, 7-13. Barberi F, Gandino A, Gioncada A, La Torre Bordoni, P., Valensise, G. (1998). Deformation of the P, Sbrana A, Zenucchini C (1994) The deep 125 Ka marine terrace in Italy: tectonic implications. structure of the Eolian arc (Filicudi-Panarea- In: Stewart, I.S., Vita-Finzi, C. (Eds.), Coastal P37 to P54 n° 5 - from Volume Vulcano sector) in light of gravity, magnetic and Tectonics, Geological Society, London, Special volcanological data. J Volcanol Geoth Res 61: Publications 146, pp. 71-110. 189-206. Büttner R., Dellino P., & Zimanowski B. (1999) Barberi, F., Rosi, M. and Sodi, A. (1993). Volcanic Identifying modes of magma/water interaction from hazard assessment at Stromboli based on review of the surface features of ash particles. Nature 401,688- historical data. Acta Vulcanologica 3, 173-187. 690. Barker D.S., 1987. Rhyolites contaminated with Calanchi N., De Rosa R., Mazzuoli R., Rossi P.L., metapelites and gabbro, Lipari, Aeolian Islands, Italy: Santacroce R., Ventura G., (1993). Silicic magma

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa isotope records terraces atHuonPeninsulawithdeepseaoxygen of lateQuaternarysealevels derived fromcoral Pandolfi Chappell, J.,Omura, A., Esat, T., Mccullock,M., (5-6), 459-467. Tyrrhenian sea evolution beneaththe Aeolian islandarc(southern from theIslandofPanarea: implicationsformantle 2002a. Petrologyandgeochemistryofvolcanic rocks F., RossiP.L., Kempton P., BarbieriM., Wu T.W., Calanchi N.,Peccerillo A., Tranne C.A.,Lucchini 215-238. volcanic islands(Aeolian Arc, Italy). the submerged areaaround Alicudi andFilicudi Morphostructural andsomepetrochemicaldatafrom Calanchi N.,RomagnoliC.,RossiP.L., 1995b. 48. (Aeolian Islands level changesandvertical displacementsatLipari (2002b). Late-Quaternaryandrecentrelative sea- C., Tranne, C.A.,Radtke, U.,Reyss, J.L.,Rossi,P.L. Calanchi, N.,Lucchi,F., Pirazzoli,P., Romagnoli, 367-395. Crisci, G.M.,Delibrias,G.,DeRosa,R.,Mazzuoli, Research 10.000 years. Volcanic historyofLipari(AeolianIslands)inthelast Cortese, M.,Frazzetta,G.,La Volpe, L.(1986). Vulcanol Evidences fromgeophysicalandgeologicaldata. early stagesofanasymmetricriftingprocess? Ventura G.(1997).MaltaEscarpment andMt.Etna: Continisio R.,FerrucciF., GaudiosiG.,LoBascioD., Geologica d’ Italia C.Romagnoli le costeitaliane”(acuradiF.L.Chiocci, S.D’Angelo, “Atlante deiterrazzideposizionalisommersilungo deposizionali sommersinelleIsoleEolie.In: Chiocci F.L. &RomagnoliC.(2002). Terrazzi isotopes andsealevel. Chappell, J.,Shackleton,N.J.(1986).Oxygen 141, 227-236. about sourceconditions. of inorganic andorganic compoundsandinferences Panarea Island(Aeolian Archipelago): distribution Valentini L.,1995a.Submarinegas-emissionfrom Calanchi N.,CapaccioniB.,MartiniM., Tassi F., Volcanol (Aeolian islands,Southern Tyrrhenian Sea dynamics andmagmamixing-anexample fromSalina entering abasalticmagmachamber:eruptive , J.,Ota, Y., Pillans,B.(1996).Reconciliation ., 55,504-522. ., 9,39.47. 27,117-133. ). Mem.DescrittivedellaCarta Journal of Volcanic andGeothermal . EarthandPlanetarySciencesLetters ). J. Volcanol. Geotherm.Res ). Journal ofQuaternaryScience , vol.58, inpress. Nature Acta Vulcanol 324,137-140. Mar. Geol ., 7(1),43- ). Bull.of ., 115, ., 123, Acta 17

G., Neri,Francalanci,L.,Rosi,M.andSbrana, De Fino,M.,La Volpe, L.,Falsaperla, S.,Frazzetta, Italy). currents atLaFossa di Vulcano (AeolianIslands, modelling thedynamicsofdilutepyroclastic density grain sizedistribution insurge depositsasatoolfor Dellino P. &La Volpe L.(2000)Structuresand Sbrana (Ed),Felici,Pisa.214-237. La Volpe, P. Dellino,M.Nuccio,E.Privitera & A. In: e valutazioni dipericolositàaLaFossa di Vulcano. dinamiche eruttive edeposizionali,scenarioeruttivo Dellino, P. &La Volpe, L.(1997)Stratigrafi Geotherm. Res, Lipari (AeolianIslands,Italy). The caseofMontePilato-RoccheRosseeruptions, transportation mechanismsofpyroclastic deposits. analysis inreconstructingfragmentationand Dellino PandLa Volpe L.(1996).Imageprocessing Res, Rosse (Lipari,Italy). pyroclastic sequenceofMontePilato-Rocche versus transportationmechanismsinthe Dellino PandLa Volpe L.(1995).Fragmentation DOI:10.1029/2003TC001506. seismological andgeochemicaldata. (Southern Tyrrhenian Sea,Italy)inlightofstructural, Geodynamic signifi De Astis G.F., Ventura G., Vilardo G., 2003, Sea Vulcano Island(Aeolian Arc, Southern Tyrrhenian (1997). Volcanological andpetrologicalevolution of De Astis, G.,La Volpe, L.,Peccerillo, A., Civetta, L. Issue 6,684-703 Contributions to Mineralogy andPetrology constraints fromtheIslandof Vulcano (Aeolianarc) environments: geochemicalandSr, Nd,Pbisotopic alkaline topotassium-richmagmatisminsubduction Volpe, L. Wu, T.W. (2000) Transition fromcalc- De Astis, G.,Peccerillo, A ,Kempton ,P.D., La Vulcano Island. of fi (1997). Eruptive andemplacementmechanisms De Astis G.,DellinoP., DeRosaR.,La Volpe L. 207-221. Arc, southernItaly component system:theIslandofLipari(Aeolian Sonnino M.(1991). Temporal evolution ofathree Crisci G.M.,DeRosaR.,EsperancaS.,Mazzuoli Bulletin of Volcanology the Late-PleistoceneBrown Tuffs onLipari,Italy. R., Sheridan,M.F. (1983). Age andpetrologyof ). J. Geoph.Res “CNR-GNV Progetto Vulcano 1993-1995 ne grainedpyroclastic depositswidespreadon 64, 211-231. J. Volcanol. Geoth.Res 71, 13-29. Bull. Volcanol cance ofthe Aeolian volcanism . 102,B4,8021-8050. ). Bulletinof Volcanology . 46-4,381-391. Jour. Volcanol. Geotherm. . 96,57-78. , 59,87-102. Jour. Volcanol. Tectonics 26-05-2004, 15:06:26 (139), , 22,4, “L.

a, 53, GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

A. (1988). The Stromboli eruption of December 6, 122. 1985-April 25, 1986: volcanological, petrological Esperanca S., Crisci G.M., De Rosa R., Mazzuoli and seismological data. Rendiconti Società Italiana R. (1992). The role of the crust in the magmatic Mineralogia Petrologia 43, 1021-1038. evolution of the Island of Lipari. Contrib. Mineral. De Rosa R (1999) Compositional modes in the ash Petrol.,112, 450-462. fraction of some modern pyroclastic deposits: their Francalanci, L., Barbieri, M., Manetti, P., Peccerillo, determination and signifi cance. Bull. Volcanol. 61: A. and Tolomeo, L. (1988). Sr-isotopic systematics in 162-173 volcanic rocks from the Island of Stromboli (Aeolian De Rosa R. & Sheridan M.F., 1983, Evidence for arc). Chemical Geology 73, 164-180. magma mixing in the surge deposits of the Monte Francalanci, L., Manetti, P. and Peccerillo, A. (1989). Guardia sequence, Lipari. In Explosive Volcanism, Volcanological and magmatological evolution of M.F. Sheridan and F. Barberi eds., Jour. Volcanol. Stromboli volcano (Aeolian Islands): the roles of Geotherm. Res., 17, 313-328. fractional crystallization, magma mixing, crustal De Rosa R., Donato P., Gioncada A., Masetti M. & contamination and source heterogeneity. Bullettin of Santacroce R., (2003b). The Monte Guardia eruption Volcanology 51, 355-378. (Lipari, Aeolian Islands): an unusual example of Francalanci, L., Manetti, P., Peccerillo A. and Keller, magma mixing sequence. Bull. Volcanol., DOI: J. (1993). Magmatological evolution of the Stromboli 10.1007/s00445-003-0281-2. volcano (Aeolian Arc, Italy): inferences from major De Rosa R., Donato P., Gioncada A., Mazzuoli and trace element and Sr-isotopic composition of R., Santacroce R. (2003c). Scenari eruttivi delle lavas and pyroclastic rocks. Acta Vulcanologica 3, eruzioni riolitiche del settore centrale eoliano: stato 127-151. delle conoscenze. GNV, General Assembly, june 9- Francalanci, L., Taylor, S.R., McCulloch, M.T., 11,p.236. Woodhead, J. (1993). Geochemical and isotopic De Rosa R., Frazzetta G., La Volpe L., 1992, An variations in the calc-alkaline rocks of the Aeolian Approach For Investigating The Depositional Arc (Southern Italy): constraints on the magma Mechanism Of Fine-Grained Surge Deposits. The genesis. Contr. Mineral. Petrol. (113), 300-313. Example Of The Dry Surge Deposits At “La Fossa Francalanci, L., Tommasini, S. and Conticelli, S. Di Vulcano”. Jour. Volcanol. Geotherm. Res., 51, (2003). The volcanic activity of Stromboli in the 305-321. 1906-1998 A.D. period: mineralogical, geochemical De Rosa R., Guillou H., Mazzuoli R. and Ventura and isotope data relevant to the understanding of G. (2003a). New unspiked K-Ar ages of volcanic the plumbing system. Journal of Volcanology and rocks of the central and western sector of the Aeolian Geothermal Researches in press. Islands: reconstruction of the volcanic stages. Jour. Francalanci, L., Tommasini, S., Conticelli, S. and Volcanol. Geotherm. Res., 120, 161-178.. Davies, G.R. (1999). Sr isotope evidence for short De Rosa R., Mazzuoli R., Ventura G., 1996,. magma residence time for the 20th century activity Relationships between deformation and mixing at Stromboli volcano, Italy. Earth Planetary Science processes in lava fl ows: a case study from Letters 167, 61-69. Salina (Aeolian Islands, Tyrrhenian Sea).Bull. of Frazzetta, G., La Volpe, L. & Sheridan, M.F. (1983) Volcanol.58,286-298. Evolution of the Fossa Cone, Vulcano. J. Volcanol. Eichelberger, J.C. (1975) Origin of andesite and Geotherm. Res., 17, 329-360. dacite: evidence of mixing at Glass Mountain in Frazzetta, G., Gillot, P.Y., La Volpe, L. & Sheridan, California and other circum-Pacifi c volcanoes. Geol M.F. (1984) Volcanic hazard at La Fossa of Vulcano: Soc Am Bull 86: 1381-1391. data from the last 6000 years. Bull. Volcanol., 47, Ellam, R.M., Hawkesworth, C.J., Menzies, M.A. and 105-124. P37 to P54 n° 5 - from Volume Rogers, N.W. (1989). The volcanism of Southern Frazzetta G., La Volpe L. and Sheridan M.F. (1989). Italy: role of subduction and the relationship between Interpretation of emplacement units in recent surge potassic and sodic alkaline magmatism. Journal of deposits on Lipari, Italy. Journal of Volcanology and Geophysical Research 94, 4589-4601. Geothermal Researches,37, 339-350. Ellam R.M., Harmon R.S., 1990. Oxygen isotope Gabbianelli G., Gillot P.Y., Lanzafame G., Romagnoli constraints on the crustal contributions to the C., Rossi P.L., 1990. Tectonic and volcanic evolution subduction-related magmatism of the Aeolian Islands, of Panarea (Aeolian Islands, Italy). Mar. Geol., 92, Southern Italy. J. Volcanol. Geotherm. Res., 44, 105- 313-326.

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P42_R_OK 37 18-06-2004, 14:38:20 P42_R_OK 38

Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa equilibria inhydroussystems. Housh, T.B. andLuhr, J.F., 1991,Plagioclase-melt Vulcanologica of theIslandStromboli, Aeolian arc,Italy. Geology, stratigraphyandvolcanological evolution Stadlbauer, E.,Francalanci,L.andLenhart,R.(1993). Hornig-Kjarsgaard, I.,Keller, J.,Koberski, U., 1046. the eastofPanarea, Aeolian Islands,Italy. investigations ofsubmarinevolcanic exhalations to Italiano F., NuccioP.M., 1991.Geochemical 76:477-492. Stromboli. budgets andsteadystateactivity of Vulcano and Harris, A.J.L. andStevenson, D.S.(1997).Magma Vulcanologica Radiochronological datingofStromboli. Gillot, P.Y. andKeller, J.(1993). anulaire ?. Eoliennes: arcinsulaireorcomplexe orogenique Gillot P.Y. (1987).Histoirevolcanique desIles Volcanology constraints onthefeedingsystem. Steady-state operationofStrombolivolcano, Italy: Giberti, G.,Jaupart,C.andSartoris,G.(1992). 191-220. by tectonics. Islands, Italy):anexample ofvolcanism controlled than 42kaontheLipari-vulcanocomplex (Aeolian M.T. (2003)Petrologyofvolcanic productsyounger Gioncada A., MazzuoliR.,BissonM.,Pareschi Per. Mineral Commenda, LaFossa, Vulcano (EolianIslands,Italy). hydrothermal-magmatic eruptionof“Brecciadi Gioncada, A., Gurioli,L.,&Sbrana, A. (1995) The Geol. Rom (Sicilia nororientale):unostudiomicrotettonico. Fiumefreddo, Tindari-Letojannie Alia-Malvagna trascorrenti edistensive lungoisistemiMessina- Ghisetti F. (1979).Relazionitrastruttureefasi 139, 607-626. Italy.Salina, AeolianArc, origin andevolution ofthecalc-alkalineseries Gertisser R.,Keller J.,2000.Frombasalttodacite: Geology portion ofthe Aeolian arc(Tyrrhenian sea). volcanic and hydrothermalfeaturesofasubmarine Gamberi F., MaraniM.,Savelli C.(1997). Tectonic, sea). area (Aeolian Arcipelago, South-eastern Tyrrhenian N., 1993.MarineGeologyofthepanarea-Stromboli Gabbianelli G.,RomagnoliC.,RossiP.L., Calanchi Acta Vulcanol. , 140,1-2,167-181. ana., 18,23-58. D.T. IGAL Geophysical Research Letters 54,535-541. ., 64,191-192. 3,21-68. Jour. Volcanol.Res., Geotherm. 3:69-77. , 3,11-20. , 11,35-42. Contrib. Mineral. Petrol American Mineralogist Bullettin of J. Volcanol. 24,1043- Marine 122, Acta Acta ., , press. vertical movements. constraints toreconstructgeologicalevolution and at Lipari(AeolianIslands):stratigraphical P.L. (2003).Late-Quaternary ancientshorelines P.A., RomagnoliC.,Radtke U.,Reyss J.L.,Rossi Lucchi F., Tranne C.A.,CalanchiN.,Pirazzoli Italiana Pleistocenico. dell’eustatismo edelsollevamento tardo- (Isole Eolie):loroutilizzonelladefinizione C.A. (1999).Iterrazzimarinidell’IsoladiPanarea Lucchi, F., Calanchi,N.,Carobene,L., Tranne Plinius evolution andvertical mobilityofthe Aeolian Islands. Lucchi, F. (2000b).LateQuaternaryvolcanic activity Italy. Quaternario. e mobilitàverticale delleIsoleEolieneltardo Lucchi, F. (2000a).Evoluzione dell’attività vulcanica 106. arc). radiogenic magmatismofStromboli(Aeolian contamination astheoriginofhigh-Sr Luais, B.(1988).Mantlemixingandcrustal Italy. Isole Eolie. deposizionali eareesorgente deitufi brunidelle Losito R.(1989).Stratigrafia, caratteri 135. lithospheric discontinuity. Islands (Sicily):importanceandevolution ofa escarpment anditsextension fromMt.Etnato Aeolian Lanzafame G.andBousquetJ.C.(1997). The Maltese Abstract Volumep.57. events. Aeolian Islands:dynamicsoffall, surge andblast of UpperQuaternaryandesiticvolcanism ofSalina, Keller, J.,Morche, W. (1993).Exceptionalexplosivity 36, 489-524. della SocietàItalianadiMineralogia ePetrografi a Keller, J.(1980). The IslandofSalina. 325. Thorpe R.S.(Ed.) Keller J.(1982).Mediterraneanislandarcs.In Verlag, experimental petrologyofgraniticrocks. Johannes W., HoltzF. (1996)Petrogenesisand volcanoes. rate andinstabilitiesoferuptionregime insilicic Jaupart C, Allègre CJ(1991)Gascontent,eruption Geotherm. Res Earth PlanetaryScienceLetters 23,101-107. 335p. IAVCEI General Assembly Canberra 1993 118,545-562. Earth Planet PhD Thesis ., 46,125-141. PhD Thesis Bollettino dellaSocietàGeologica Andesites. WileyChichester Quaternary International

Sci Letters , Università diBologna, Acta Vuolcanol , Università diBari, 102: 413-429. Rendiconti ., 9,121- 88,93- Springer 26-05-2004, 15:06:31 , 307- , in ,

GEOLOGY AND VOLCANISM OF STROMBOLI, LIPARI, AND VULCANO (AEOLIAN ISLANDS) P42

Lucchi F., Tranne C.A., Calanchi N., Pirazzoli P.A., Geophys Res 93: 11.949-11.959. Romagnoli C., Rossi P.L. (2003). Late-Quaternary and Santo A., Chen Y., Clark A.H., Farrar E. and recent sea-level changes and vertical displacements Tsegaye A. (1995). 40Ar/39Ar ages of the Filicudi in the Aeolian Arc (Southern Tyrrhenian Sea). In: islan volcanics: implications for the volcanological Riassunti e guida alle escursioni; workshop: “Il history of the Aeolian Arc, Italy. Acta Vulcanol., 7, contributo dello studio delle antiche linee di riva 13-18. alla comprensione della dinamica recente. Escursioni Savelli C. (2000). Two-stage progression of nello stretto di Messina”. Messina 6-8 maggio 2003; volcanism (8-0 Ma) in the central Mediterranean 33-35. (southern Italy). Jour. Of Geodynamics, 31, 87- Lucchi F., Tranne C.A., Calanchi N., Rossi P.L. 104. (2004). Geological cartography in volcanic areas: Sheridan, M.F., Frazzetta, G., La Volpe, L., the case of Lipari (Aeolian Islands). In Atlante di 1987. Eruptive histories of Lipari and Vulcano, cartografi a geologica, Pasquaré G., Venturini C. Italy, during the past 22.000 years. In: J.H. Fink (eds). Convegno Geologico Internazionale, Firenze (Editor), The emplacement of silicic domes and 2004, in press. lava flows. Geol. Soc. Am., Spec. Pap. 212, 29- Marani M.P. and Trua T. (2002) Thermal 34. constriction and slab tearing at the origin of a Tibaldi, A. (2001). Multiple sector collapses at superinflated spreading ridge: Marsili volcano Stromboli volcano, Italy: how they work. Bullettin of (tyrrhenian Sea). Jour. Geoph. Res., 107, 10.1029/ Volcanology 63 (2/3), 112-125. JB00285. Tranne, C.A., Lucchi, F., Calanchi, N., Métrich N., Bertagnini A., Landi P. and Rosi, M. Lanzafame, G., Rossi, P.L. (2002). Geological (2001). Crystallization driven by decompression map of the Island of Lipari (Aeolian Islands). and water loss at Stromboli volcano (Aeolian L.A.C., Firenze. Islands, Italy). Journal of Petrology 42, 1471- Vaggelli, G., Francalanci, L., Ruggieri, G. and 1490. Testi, S. (2003). Persistent polybaric rests of Nazzareni, S., Molin, G., Peccerillo, A., Zanazzi, calc-alkaline magmas at Stromboli volcano, Italy: P.F. (2001). Volcanological implications of crystal- pressure data from fluid inclusions in restitic chemical variations in clinopyroxenes from the quartzite nodules. Bullettin of Volcanology 65, Aeolian Arc, Southern Tyrrhenian Sea, Italy. Bull. 385-404. Volcanol. (63), 73-82 Vai, G.B. (1996). Revisione critico-storica dei Piani Pasquarè, G., Francalanci, L., Garduño, V.H. and marini del Quaternario. Servizio Geologico d’Italia, Tibaldi, A. (1993). Structure and geologic evolution Miscellanea, Vol. 6. Istituto Poligrafi co e Zecca dello of the Stromboli volcano, Aeolian islands, Italy. Acta Stato, Roma, 179 pp. Vulcanologica 3, 79-89. Ventura G., Vilardo G., Milano G., Pino N. A. (1999). Renzulli , A., Serri , G., Santi , P., Mattioli , M., Relationships among crustal structure, volcanism and Holm, P.M. (2001) Origin of high-silica liquids at strike-slip tectonics in the Lipari-Vulcano volcanic Stromboli volcano (Aeolian Islands, Italy) inferred complex (Aeolian Islands, Southern Tyrrhenian Sea, from crustal xenoliths, Bull. Volcanol. (62), Issue Italy). Physics of the Earth and Planetary Interior, 6/7, pp 400-419. 116, 31-52. Romagnoli, C., Kokelaar, P., Rossi, P.L. and Sodi, Volpi V., Del Ben A., Martini F., Finetti I. (1997) A. (1993). The submarine extension of the Sciara Elaborazione ed Interpretazione della linea CROP- del Fuoco feature (Stromboli isl.): morphologic MARE 2A5 nel bacino di Gioia (Tirreno Sud- charcterisation. Acta Vulcanologia 3, 91-98. Orientale). Proc. 16° Nat. Conv., GNGTS-CNR, Cd- Rosi, M. (1980). The Island of Stromboli. Rendiconti rom, 07.06 P37 to P54 n° 5 - from Volume Società Italiana Mineralogia e Petrologia 36, 345- Voltaggio, M., Branca, M., Tuccimei, P. & Tecce, 368. F. (1995) Leaching procedure used in dating Rosi, M., Bertagnini, A. and Landi, P. (2000). Onset young potassic volcanic rocks by the 226Ra/230 of the persistent activity at Stromboli volcano (Italy). Th method. Earth Planet. Sc. Lett., 136, 123- Bullettin of Volcanology 62, 294-300. 131. Rutherford MJ, Devine JD (1988) The May 18, Wang C.Y., Hwang W.T., Shi Y. (1989) Thermal 1980, eruption of Mount St. Helens. 3- Stability and evolution of a rift basin: the Tyrrhenian Sea. Jour. chemistry of amphibole in the magma chamber. J Gephys. Res., 94, 3991-4006.

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Volume n° 5 - from P37 to P54 P42 - P42 Leader: R.DeRosa Nature explosive andeffusive eruptionsofsilicicmagmas. Woods AW, Koyaguchi T (1995) Transitions between 6): 1025-1040. geothermometry.” the ternaryfeldsparsolvusandfortwo feldspar interactive graphicsprogrampackageforcalculating Wen, S.&Nekvasil H.(1994).“SOLVCALC: An , 370:641-64 Computers &Geosciences 20(No. 26-05-2004, 15:06:35 Back Cover: fi eld trip itinerary

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