http://hdl.handle.net/2122/221 2013-05-25T22:58:10Z http://hdl.handle.net/2122/8610 Title: Trioctahedral micas in xenolithic ejecta from recent volcanism of the Somma-Vesuvius (Italy): crystal chemistry and genetic inferences. Authors: Balassone, G.; Dipartimento di Scienze della Terra, Università “Federico II”, via Mezzocannone 8, I-80134 Napoli, Italy; Scordari, F.; Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari, via Orabona 4, I-70125 Bari, Italy; Lacalamita, M.; Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari, via Orabona 4, I-70125 Bari, Italy; Schingaro, M.; Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari, via Orabona 4, I-70125 Bari, Italy; Mormone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Piochi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Petti, C.; Dipartimento di Scienze della Terra, Università “Federico II”, via Mezzocannone 8, I-80134 Napoli, Italy; Mondillo, N.; Centro Museale “Musei delle Scienze Naturali”, Università “Federico II”, via Mezzocannone 8, I-80134 Napoli, Italy Abstract: This study reports the first crystal chemical database resulting from a detailed structural investigation of trioctahedral micas found in xenolithic ejecta produced during the AD 1631, 1872 and 1944 eruptions, three explosive episodes of recent volcanic period of Vesuvius volcano (Southern Italy). Three xenolith types were selected: metamorphic/metasomatic skarns, pyrometamorphic/hydrothermally altered nodules and mafic cumulates. They are related to different magma chemistry and effusive styles: from sub-plinian and most evolved (AD 1631 eruption) to violent strombolian with medium evolution degree (AD 1872 eruption) to vulcanian-effusive, least evolved (AD 1944 eruption) event, respectively. Both xenoliths and micas were investigated employing multiple techniques: the xenoliths were characterized by X-ray fluorescence, inductively-coupled plasma-mass spectrometry, optical microscopy, X-ray powder diffraction, and quantitative energy-dispersive microanalysis; the micas were studied by electron probe microanalysis and single crystal X-ray diffraction. The mica-bearing xenoliths showvariable texture and mineralogical assemblage, clearly related to their different origin. Based on the major oxide chemistry, only one xenolithic sample falls in the skarn compositional field fromthe Somma-Vesuvius literature, some fall close to the skarns and cumulate fields, others plot close to the syenite/foidolite/essexite field. A subgroup of the selected ejecta does not fall or approach any of the compositional fields. Trace and rare earth element patterns show some petrological affinity between studied xenoliths and erupted magmas with typical Eu, Ta and Nb negative anomalies. Strongly depleted patterns were detected for the 1631 metamorphic/metasomatic skarns xenoliths. Three distinct mica groups were distinguished: 1) Mg-, Al-rich, low Ti-bearing, low to moderate F-bearing varieties (1631 xenolith), 2) Al-moderate, F- and Mg-rich, Ti-, Fe-poor varieties (1872 xenolith), and 3) Al-, Ti- and Fe-rich, F-poor phases (1944 xenolith). All the analyzed mica crystals are 1Mpolytypes with the expected space group C2/m. Micas from xenoliths of the 1631 Vesuvius eruption are phlogopites characterized by a combination of low extent of oxy-type and variable extent OH−→F− substitutions, as testified by the range of F concentration (from ~0.20 to 0.80 apfu). Micas from xenoliths of the 1872 Vesuvius eruption exhibit structural peculiarities typical of fluorophlogopites, i.e. OH−→F− substitution is predominant. Micas from the xenolith of the 1944 Vesuvius eruption display features typical of oxy-substituted micas. The variability of the crystal chemical features of the studied micas is consistentwith the remarkable variation of their host rocks. Micas from1631 nodules are related to metasomatic, skarn-type environment, deriving from the metamorphosed wall-rocks hosting the magma reservoir. The fluorophlogopites from the 1872 xenoliths testify for strongly dehydrated environmental conditions compared to those of the 1631 and 1944 hosts. Finally, magma storage condition at depth, associated to a decreasing aH2O may have promoted major oxy-type substitutions in 1944 biotites. 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8609 Title: Enhanced crystal fabric analysis of a lava flow sample by neutron texture diffraction: A case study from the Castello d’Ischia dome Authors: Walter, J. M.; Mineralogisch-Petrologisches Institut, Universität Bonn, Poppelsdorfer Schloss, D-53115, Bonn,; Iezzi, G.; Dipartimento di Ingegneria e Geologia (INGEO), Università G. d’Annunzio, Chieti, Italy; Albertini, G.; Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche,; Gunther, M. E.; Department of Geological Sciences, University of Idaho, Moscow, Idaho, USA; Piochi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Jansen, E.; Mineralogisch-Petrologisches Institut, Universität Bonn, Bonn, Germany; Fiori, F.; Di.S.C.O., Sez. di Biochimica, Biologia e Fisica, Università Politecnica delle Marce, Ancona, Italy Abstract: The crystal fabric of a lava has been analyzed for the first time by neutron texture diffraction. In this study we quantitatively investigate the crystallographic preferred orientation of feldspars in the Castello d’Ischia (Ischia Island, Italy) trachytic exogenous dome. The crystallographic preferred orientation was measured with the monochromatic neutron texture diffractometer SV7 at the Forschungszentrum Jülich in Germany and a Rietveld refinement was applied to the sum diffraction pattern. The complementary thin section analysis showed that the three-dimensional crystal shape and the corresponding shape preferred orientation are in agreement with the quantitative orientation distributions of the neutron texture data. The (0k0) crystallographic planes of the feldspars are roughly parallel to the local flow bands, whereas the other corresponding pole figures show that a pivotal rotation of the anorthoclase and sanidine crystals was active during the emplacement of this lava dome. In combination with scanning electron microscopy investigations, electron probe microanalysis, XRF, and X-ray diffraction, the Rietveld refinement of the neutron diffraction data indicates a slow cooling dynamic on the order of several months during their crystallization under subaerial conditions. Results attained here demonstrate that neutron texture diffraction is a powerful tool that can be applied to lava flows. 2013-01-30T23:00:00Z http://hdl.handle.net/2122/8586 Title: SU ALCUNI “ASPETTI GEOLOGICI E MINERALOGICI DELL’ISOLA DI PROCIDA" (con note all’articolo) Authors: Russo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Editors: Centro Studi Isola d'Ischia Abstract: ll 31 ottobre del 1984 tenni presso la Biblioteca Antoniana di Ischia una conferenza sulla geologia e su alcuni minerali interessanti dell’Isola di Procida. Ora a distanza di quasi trent’anni, e sono tanti per la geologia e la mineralogia, mi è stato chiesto gentilmente di pubblicare l’evento; ovviamente molto è cambiato da allora, ma per non stravolgere l’impostazione iniziale ho preferito aggiungere nel testo alcune note in corsivo che spiegano meglio le ricerche attuali che continuano ancora. Nel testo tra parentesi quadre sono riportati i lavori successivi alla conferenza. 2012-09-30T22:00:00Z http://hdl.handle.net/2122/8585 Title: Type Minerals from the Island of Vulcano, Aeolian archipelago, Sicily, Italy Authors: Russo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Campostrini, I.; Dipartimento di Chimica, Università di Milano Editors: Comitato Scientifico A. Rittmann; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: The Aeolian archipelago consists of seven islands of volcanic origin, arranged along an arc 90 km long that extends westward with other submerged volcanoes. The Vulcano Island is the southernmost and the third largest of these islands. The island of Vulcano has an age of about 120,000 years... 2012-12-11T23:00:00Z http://hdl.handle.net/2122/8575 Title: D’ansite-(Mn), IMA 2011-064. CNMNC Newsletter No. 11, December 2011 Authors: Campostrini, I.; Dipartimento di Chimica, Università di Milano; Demartin, F.; Dipartimento di Chimica, Università di Milano; Castellano, C.; Dipartimento di Chimica, Università di Milano; Gramaccioli, C.M.; Dipartimento di Chimica, Università di Milano; Russo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: Mn2+-analogue of d'ansite 2010-12-31T23:00:00Z http://hdl.handle.net/2122/8564 Title: LAFOSSAITE E DIMORPHITE: DUE NUOVE SPECIE PER IL VESUVIO Authors: Campostrini, I.; Dipartimento di Chimica, Università di Milano; Russo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: La presenza di lafossaite, la cui località-tipo è il cratere de La Fossa all’Isola di Vulcano (Roberts et al., 2006), è stata rilevata su due piccoli campioni provenienti dal Vesuvio (eruzione del 1906), facenti parte di una vecchia collezione già appartenuta all’“Istituto Geomineralogico Italiano”, una società attiva negli anni ’20 del secolo scorso. Nei campioni esaminati la lafossaite forma minuscoli aggregati di cristalli cubici incolori, associati a realgar, dimorphite, anidrite e a un cloruro di tallio e arsenico attualmente in fase di studio. La dimorphite, la cui località-tipo è la Solfatara di Pozzuoli, fu descritta per la prima volta da Scacchi (1849) ed è associata a realgar e mascagnite. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8563 Title: D’ansite-(Mn), Na21Mn2+(SO4)10Cl3 and d’ansite-(Fe), Na21Fe2+(SO4)10Cl3, two new minerals from volcanic fumaroles Authors: Demartin, F.; Dipartimento di Chimica, Universita` degli Studi di Milano,; Campostrini, I.; Dipartimento di Chimica, Universita` degli Studi di Milano,; Castellano, C.; Dipartimento di Chimica, Universita` degli Studi di Milano,; Gramaccioli, C.M.; Dipartimento di Chimica, Universita` degli Studi di Milano,; Russo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: The new minerals d’ansite-(Mn), Na21Mn2+(SO4)10Cl3, and d’ansite-(Fe), Na21Fe2+(SO4)10Cl3, occur as encrustations in fumaroles at Vesuvius, Naples, Italy and La Fossa crater, Vulcano, Aeolian Islands, Italy, respectively. Both minerals are cubic and crystallize in space group I4¯ 3d. D’ansite-(Mn) forms colourless translucent tristetrahedral crystals up to 0.2 mm on edge; d’ansite-(Fe) forms aggregates of colourless to white complex isometric crystals of about the same size. Chemical analyses obtained by energy-dispersive spectrometry on an electron microprobe gave the following mean compositions: d’ansite-(Mn), Na2O 39.37, MnO 3.46, MgO 0.13, SO3 49.99, Cl 6.36, O=Cl 1.44, total 97.87 wt.%, c o r r e s p o n d i n g t o a n e m p i r i c a l f o r m u l a , on t h e ba s i s o f 43 a n i o n s , of Na20.61(Mn2+ 0.79Mg0.05)S0.84S10.13O40.09Cl2.91; and d’ansite-(Fe), Na2O 39.12, FeO 4.18, MgO 0.12, SO3 49.91, Cl 6.81, O=Cl 1.54, total 98.60 wt.%, corresponding to an empirical formula of Na20.42(Fe2+ 0.94Mg0.05)S0.99S10.08O39.89Cl3.11. The six strongest reflections in the X-ray powder diffraction pattern of d’ansite-(Fe) [listed as dobs(A˚) (I) (hkl)] are as follows: 2.807(100)(044), 2.570(37)(235), 1.714(29)(129), 3.384(27)(233), 3.113(26)(134), 2.108(15)(237). The unit-cell parameters obtained from single-crystal data are 15.9291(9) and 15.882(3) A ˚ for d’ansite-(Mn) and d’ansite-(Fe), respectively. The structure of both minerals was refined, using single-crystal diffraction data, to final R parameters of 0.0309 and 0.0336 on reflections with I > 2s(I). The structure contains three independent Na sites, one of which is partially occupied by Mn2+ or Fe2+, two independent sulfate anions and one chlorine site. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8332 Title: Relationship between petrologic processes in the plumbing system of Mt. Etna and the dynamics of the eastern flank from 1995 to 2005 Authors: Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Di Renzo, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Distefano, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Miraglia, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Civetta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: Mt. Etna volcano is located in a complex tectonic setting, with large sectors of its eastern flank sliding seaward at different rates. According to recent petrologic studies, the Etna's plumbing system has a multifaceted geometry, variable in space and time and consisting of storage zones at different depths, where magma ascending to the surface undergoes various processes, mainly fractional crystallization and mixing. In this framework we investigated a possible cause–effect relationship between the flank displacement and pre-eruptive magmatic processes in the shallow plumbing system (b5 km b.s.l.) during the decade 1995–2005. In particular, we analyzed petrography, mineral chemistry, geochemistry, Sr and Nd isotopes of the products emitted from 1995 to 2001 by the four summit craters of Etna (South-East, North-East, Bocca Nuova and Voragine). Results integrated with petrologic data already available in literature for the investigated decade, allowed us to better constrain the temporal evolution of the magmatic processes occurring in the Etna's shallow plumbing system (mainly mixing between compositionally and isotopically distinct magmas and fractional crystallization), and to make inferences on its geometry. Furthermore, a comparison between petrologic data and deformative patterns evidences that, from 1995 to July 2001, the aforementioned pre-eruptive magmatic processes did not significantly influence the volcano eastern flank dislocation, which stayed slow and fairly regular. By contrast, the onset of the 2001 flank eruption leads to an acceleration of the movement as a consequence of the ascent, of a primitive, volatile-rich, subaphyric basaltic magma from a deeper (about 10 km b.s.l.) reservoir, during the 2001 and 2002–03 activity. At least for the decade 1995–2005, pre-eruptive magmatic processes in the shallow portion (b5 km b.s.l.) of Etna's plumbing system, did not directly affect the movement of the volcano's eastern flank. Conversely, a magma intrusion which forcefully opens a new path from a deeper zone (about 10 km b.s.l.) of the plumbing system, causes a dramatic increase of deformative pattern, which strongly accelerates the slide of the eastern flank, as occurred during both 2001 and 2002–03 eruptions. 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8313 Title: Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera Authors: Pappalardo, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Mastrolorenzo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8233 Title: Influence of granitoid textural parameters on sediment composition: Implications for sediment generation Authors: Caracciolo, L.; Dipartimento di Scienze della Terra, Università della Calabria, Rende (CS), Italy; Tolosana-Delgado, R.; Dept. d'Enginyeria Hidràulica i Ambiental, Laboratori d'Enginyeria Marìtima (LIM/UPC) Universitat politecnica de Catalunya, Barcelona, Spain; Le Pera, E.; Dipartimento di Scienze della Terra, Università della Calabria, Rende (CS), Italy; von Eynatten, H.; Geowissenschaftliches Zentrum der Georg-August-Universität Göttingen, Abteilung Sedimentologie/Umweltgeologie, Göttingen, Germany; Arribas, J.; Dpto. de Petrología y Geoquímica, Univ. Complutense de Madrid-CSIC, Madrid, Spain; Tarquini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia Abstract: The aim of this study is to determine and characterise the control exerted by parent rock texture on sand composition as a function of grain size. The sands investigated were generated from granitoid parent rocks by the Rhone, Damma and Sidelen glaciers, which drain the Aar Massif in the Central Alps (Switzerland), and were deposited in glacial and fluvio-glacial settings. Mechanical erosion, comminution (crystal breakdown and abrasion) and hydraulic sorting are the most important processes controlling the generation of sediments in this environment, whereas chemical and/or biochemical weathering plays a negligible role. By using a GIS-based Microscopic Information System (MIS), five samples from the glacier-drained portions of the Aar basement have been analysed to determine textural parameters such as modal composition, crystal size distribution and mineral interfaces (types and lengths). Petrographic data of analysed sands include traditional point counts (Gazzi-Dickinson method, minimum of 300 points) as well as textural counts to determine interface types, frequency, and polycrystallinity in phaneritic rock fragments. According to Pettijohn's classification, grain‐size dependent compositions vary from feldspathic litharenite (0φ fraction) via lithic arkose (1φ and 2φ) to arkose (3φ and 4φ). Compositional differences among our data set were compared to modern plutoniclastic sands from the Iberian Massif (Spain) and the St. Gabriel Mts. (California, USA), which allowed us to assess the role exerted by glaciers in generating sediments. By combining data from the MIS with those from petrographic analysis, we outlined the evolution of mineral interfaces from the parent rocks to the sediments. 2011-12-31T23:00:00Z