0000000000192960
AUTHOR
Silvio Giuseppe Rotolo
OH-related infrared bands in oxide glasses
Natural degassing activity of the geothermal system of Soussaki(Greece):Environmental impact and gas hazard issues.
Low-P hydrous phase equilibria of a pantellerite melt: constraints on pre-eruptive conditions of recent felsic explosive volcanism at Pantelleria.
Geochronology of the medium-high-grade units of the Peloritani Mts., Sicily.
The Peloritani Mountains are a fragment of an orogen variably attributed to the Alpine or Hercynian orogeny. On the basis of Ar-39-Ar-40, U-Pb and Rb-Sr dating, the main metamorphism of the two medium-high grade metamorphic units, the Mela and Aspromonte Units, and most of the thrusting responsible for stacking the orogenic edifice are seen to be Hercynian. The main thrusting of the Aspromonte Unit over the lower grade units took place at 301+/-2 Ma. Brittle deformation during Tertiary reactivation of Hercynian thrust planes did not generate any rejuvenation of white micas in the studied sector. Our dataset shows a great complexity and we propose to unravel it by considering different level…
New Inferences on Magma Dynamics in Melilitite-Carbonatite Volcanoes: The Case Study of Mt. Vulture (Southern Italy)
This study provides the first micro-thermometric data of fluid inclusions (FIs) in mafic loose (disaggregated) xenocrysts and ultramafic xenoliths in explosive products of the melilitite-carbonatite Mt. Vulture volcano (southern Italy). Pure CO2 late stage FIs hosted in rock-forming minerals of wehrlite xenoliths and clinopyroxene xenocrysts were trapped at the local crust-mantle boundary (32 km). In contrast, trapping pressures within the loose olivine xenocrysts are from 3.2 to 4.5 kbar (8–13 km). Considering the ongoing degassing of mantle-derived CO2 rich gases, together with seismic evidences of the presence of low amount of melts at depth, and the tectonic control of the past volcanic…
Local earthquakes tomography in the southern tyrrhenian region (italy): geophysical and petrological inferences on subducting lithosphere
Seismic velocity structures of Southern Italy from tomographic imaging of the Ionian slab and petrological inferences.
International audience; In this study we have determined detailed Vp and Vs seismic velocity models of the Ionian lithosphere subducting beneath the Tyrrhenian basin and of the surrounding mantle, by applying a post-processing technique to a large sample of local earthquake tomography studies. Our seismic velocity models permit us to infer the presence of low velocity anomalies within the slab, which we interpret as regions that are partially hydrated by fluids released during the subduction process. A petrological interpretation of the velocity anomalies gives new details on the magmatism of the volcanic Aeolian arc. Furthermore our velocity models provide a more detailed description of th…
A window into the high velocity body (HVB) beneath Mt. Etna:a cntribution from the study of cognate xenoliths in historical lavas
Submarine volcanism in the Sicily Channel: the messagge from a deep mantle reservoir.
Geology and petrochemistry of recent (25 ka) silicic volcanism at Pantelleria Island
built a complex sequence of interfingered deposits emitted by closely spaced eruptive vents which are frequently associated with dome-building phases and pantelleritic lavas flows. Field relationships allowed us to recognize eight eruptive units, all lying above the Montagna Grande trachytes. As a whole, petrochemical characteristics of the erupted products indicate an evolutionary trend in which Na-clinopyroxene was the liquidus phase, followed by alkali feldspar. Amphibole and quartz are late-crystallizing, whereas aenigmatite is both early- and late-crystallizing as well. Aenigmatite and Na-clinopyroxene crystallization buffers efficiently the increase of agpaicity, induced by feldspar c…
Submarine volcanism in the Sicily Channel Rift: new data from Graham, Nameless and Pantelleria Banks
Local earthquake tomography in the Southern Tyrrhenian region of Italy: Geophysical and petrological inferences on subducting litosphere
We obtained a high-resolution seismic tomography of the Ionian lithosphere subduction using a new approach based on: (a) the Double-Difference technique for inversions and (b) the statistical post-processing of a great number of preliminary models (Weighted Average Model, WAM method); the latter was used to increase reliability and resolution. In the tomographic model, the high-velocity portion of the steeply dipping Ionian slab is well imaged, as is an underlying low-Vp (≈7.0 km/s) aseismic region. We propose that the low-velocity region can be assigned to a partially hydrated (serpentinized) mantle of the subducting Ionian slab, which progressively dehydrates with depth in dense high-pres…
Ascent of Stromboli yellow pumice magmas: experimental simulation at P
THE ARGONAUTICA ORPHICA VERSION FOR THE VOYAGE OF THE ARGONAUTS: A GEO-ANALYSIS
This study traces and analyzes the itinerary followed by Argo and her crew, according to the unknown author of Argonautica Orphica: The voyage of the Argonauts from Iolcos to Colchis and their return following a different path, from Phasis River through central Europe to the Atlantic Ocean and then through the Mediterranean Sea. Conclusions are drawn about whether such a voyage could be possible in the remote antiquity and the “problematic” points of the description are pointed out.
Local earthquake tomography in the Southern Tyrrhenian region (Italy): Geophysical and petrological inferences on subducting litosphere.
WAM tomography in the southern Tyrrhenian region : petrological inferences and hypothesis on the fluid circulation in the subducting Ionian slab and adjoining mantle domains
Evidence of basaltic magma intrusions in a trachytic magma chamber at Pantelleria (Italy)
In the last 50 ka basalts have erupted outside the margin of the young caldera on the island of Pantelleria. The inner portion of the caldera has instead been filled by trachyte lavas, pantellerite lavas and pumice fall deposits. This paper focuses on a low-volume benmoreite lava topping the trachyte lava pile in the middle of the young caldera. The mineral chemistry, including trace elements in clinopyroxene (LA-ICP-MS), suggests that benmoreite is a hybrid product resulting from mixing between a trachytic magma and a basaltic end member even more primitive than those erupted during the past 50 ka. The principal inference is that basaltic magmas intruded the trachytic magma chamber below t…
Sulphur behaviour in Etnean magmatic system (Italy
Sulfur is an essential volatile component of basaltic magmas and it is mostly dissolved as S6+ and/or S2- depending on the redox conditions. Mt. Etna continuously discharges enormous quantity of SO2 (~3563 t/d [1]). However these high flows are not fully understood in terms of S origin (magmatic or crustal) and of its behavior during magmatic evolution (fractional crystallization, magma mixing, vapor/melt fractionation [2]). Our research combines the study of sulfur in natural olivine hosted melt inclusions with an experimental study on S solubility in hydrous alkali basalts at magmatic conditions. We report new data of S in melt inclusions, belonging to six of the most characteristic Etnea…
A revised stratigraphy of the pre-Green Tuff ignimbrites at Pantelleria (Sicily Channel)
Peralkaline silicic magmas were erupted at Pantelleria in a variety of eruptive typologies and magnitudes: pyroclastic flows, Plinian to strombolian pumice fallout and lava flows. The initial cycle (330- 180 ka) was characterized mainly by effusive activity, and was followed by an intermediate cycle (181 - 85 ka), characterized by a clear drift to explosive activity. This period, onto we focus, is bracketed by six ignimbrite-forming eruptions (older and intermediate of the two caldera collapses at 140 and 50 ka that characterize the volcanological history of the island, which drained silicic and variably peralkaline magma for a cumulative volume close to 6 km3 DRE. These ignimbrites lack of…
Sulfur in hydrous, oxidized basaltic magmas: phase equilibria and melt solubilities.
OH-related infrared absorption bands in oxide glasses
Crystallization of Pantelleria basalt: preliminary reults
Transition from mildly-tholeiitic to calc-alkaline suite: the case of Chichontepec volcanic centre, El Salvador, Central America.
Hydrothermal processes with REE enrichment in Fuerteventura carbonatites: evidences in accessory minerals
Los diques carbonatíticos que afloran en la parte centro-occidental del Complejo Basal de Fuerteventura (Ajuy, Punta de la Nao), fueron afectados por el evento intrusivo mioceno responsable del metamorfismo de contacto y fusión parcial de parte del complejo alcalino-carbonatítico. Las características texturales, los procesos de formación de monacita enriquecida en LREE (La, Ce, Nd) en microfracturas que afectan a los cristales de zircón, evidencian interacciones de las carbonatitas con fluidos hidrotermales y removilización parcial de REE. El pirocloro es el principal mineral reservorio de tierras raras (suma REE=216694 ppm), con valores elevados de LREE (LaN=185816 y CeN=165209) respecto a…
Dal mantello terrestre ai vulcani. Uno sguardo al vulcanismo degli ultimi 2 Ma nel Mediterraneo.
Gli esperimenti ad alta pressione e temperatura (petrologia sperimentale) sono il mezzo più efficace di cui si dispone per la conoscenza dell’interno della Terra, dalla crosta al nucleo. Gli apparati necessari alla riproduzione delle temperature (comprese tra i 1000 e gli oltre 3500 °C) e pressioni variabili dai 10 kbar agli oltre 3 Mbar (corrispondenti a profondità comprese tra 30 e 5000 km), sono particolarmente sofisticati e sono accoppiati a raffinati metodi di analisi dei prodotti sperimentali (durante e dopo gli esperimenti). A questo tipo di studi si deve la conoscenza dell’ interno della Terra, soprattutto della Terra Inaccessibile (mantello inferiore e nucleo), avendo permesso di c…
New Insights into the Provenance of the Obsidian Fragments of the Island of Ustica (Palermo, Sicily)
In this study we applied a multidisciplinary approach, coupling geophysical and geochemical measurements, to unveil the provenance of 170 obsidian flakes, collected on the volcanic island of Ustica (Sicily). On this island there are some prehistoric settlements dated from the Neolithic to the Middle Bronze Age. Despite not having geological outcrops of obsidian rocks, the countryside of Ustica is rich in fragments of this volcanic glass, imported from other source areas. The study of obsidian findings was carried out first through visual observations and density measurements. At least two different obsidian families have been distinguished, probably imported from Lipari and Pantelleria isla…
A two-component mantle below Mt Etna volcano: evidences from noble gas and trace element geochemistry of primitive products
A general geochemical study comprehensive of major elements, trace elements and Sr-Nd isotopes in the bulk rock, coupled to noble gases analyses from fluid inclusions retained in minerals, was performed. The studied samples ( basalts, trachybasalts and basanites) represent some among the most primitive products of Etnean history. The variable composition measured in trace elements (i.e. Zr/Nb=2.81–4.98, Ce/Yb=35.02–66.90, La/Yb=15.36–35.52, Th/Y=0.17–0.43) was modeled as due to varying degrees of melting of a common mantle source. We numerically simulated the process by MELTS code to calculate a melting percentage for each product, and we accordingly estimated the pristine trace-elements co…
Petrologic constraints on melting conditions in the Strait of Sicily Rift Zone.
The Strait of Sicily Rift Zone (SSRZ) is a northwest-southeast trending transtensional rift situated in the Mediterranean Sea between Sicily and north Africa. The SSRZ consists of three basins: the Pantelleria Trough, the Linosa Basin, and the Malta Trough. Volcanoes are situated in or adjacent to all except the Malta Trough, and include two islands (Pantelleria and Linosa) and several seamounts. The thickness of the crust throughout the region is 25-35 km, but thins to 16-18 km in the basins of the SSRZ. The Pantelleria Trough is characterized by high average heat flow values and a strong positive Bourger anomaly, which suggest assthenospheric upwelling to ~60 km and the presence of abunda…
Fumarolic alteration products at Sousaki (Greece) : occurrence and environmental impact
Fumarolic alteration crusts and efflorescences have been sampled at the Sousaki solfataric field. Samples have been analysed for mineralogical (XRD) and chemical composition (HNO3 digestion and leaching with distilled water). Results show that mineralogical and chemical compositions (major, minor and trace metals) are controlled by microenvironmental conditions. The sample collected in the anoxic part of a cave is composed almost exclusively by native sulfur. The samples collected in the oxidizing part of the cave and outside in relatively sheltered position are mainly composed by very soluble sulfates. Chemical composition evidence strong enrichments in Al, Ca, Cr, Fe, Mg and Ni which are …
A two-component mantle extending from Hyblean Plateau to Mt Etna (Eastern Sicily) as inferred by an integrated approach with noble gases, trace elements and isotope geochemistry.
We carried out a geochemical investigation of the mantle beneath Hyblean and Etnean area through ultramafic xenoliths (peridotites and pyroxenites) retained in Miocenic age Hyblean volcanics and primitive Etnean lavas and tephra, respectively. Major and trace elements and Sr-Nd isotopes (whole rock and /or minerals) were analysed together with noble gases entrapped in fluid inclusions hosted in olivines and pyroxenes phenocrysts. The geochemical results from Hyblean xenoliths study highlighted the presence of two distinct compositional groups: the peridotites, featured by a more enriched geochemical fingerprint (3He/4He ∼7 Ra, 143Nd/144Nd ∼0.5129 and Zr/Nb ∼ 4) whereas the pyroxenites, char…
TEPHROCRONOLOGY WITH 40AR–39AR DATING OF RECENT SILICIC VOLCANISM AT PANTELLERIA ISLAND: IMPLICATIONS ON MAGMATIC SYSTEM.
Mafic and ultra-mafic enclaves from Ustica island lava: inferences on deep magmatic processes
Ustica Island, southern Tyrrhenian Sea, is constituted of Quaternary alkaline volcanics. Avariety of enclaves representative of deep to supra-crustal settings were recently found in a hawaiitic lava flow. Enclaves consist of: (i) Ultramafic meta-cumulates, i.e. clinopyroxenites and wherlites characterized by variably deformed porphyroclastic to granoblastic textures. (ii) Mafic cumulates, i.e. gabbros (F amphibole) and troctolites, the first often characterized by frequent amphibole breakdown coronas (olivine+Tiaugite+ plagioclase+magnetite+ilmenite+rhfnite) in response to an H2O decrease during the ascent, while the troctolites interpreted as meta-cumulates. (iii) Microsyenites, consist of…
modelling of the subducting slab beneath the south tyrrhenian basin with geophisical and geochemical data
Petrology of some amphibole-bearing volcanics of the pre-Ellittico period (102-80 ka), Mt. Etna
We present here petrological and geochemical data on volcanics cropping out in southern and northeastern walls of the Valle del Bove (Mt. Etna), belonging to the Rocche, Serra Giannicola Grande and Canalone della Montagnola Units. These units constitute the remnants of several volcanoes that were active in the time span 102-80 ka, i.e. before the growth of the Ellittico-Mongibello strato-volcano. Their products, range in composition from hawaiites to benmoreites. Amphibole (kaersutite) is present as phenocryst in all the studied rocks, and commonly shows breakdown coronas of rhönite ± clinopyroxene and plagioclase formed during magma ascent. Nevertheless, in mafic rocks, amphibole occurs as…
Sul ritrovamento di tephra di composizione riolitica peralluminosa a largo del promontorio di Capo Vaticano (Calabria Occidentale, Tirreno Meridionale)
39Ar/40Ar dating of an alkali-granite enclave from Pantelleria island.
Clinopyroxene-bearing garnet amphibolites from the Ferrà valley (northern Peloritani Mts., Sicily
Recent felsic explosive magmatism at Pantelleria island: an experimental study
Experimental constraints on pre-eruptive conditions of a chemically-zoned peralkaline ignimbrite: the Green Tuff eruption at Pantelleria Island (Italy)
Pantelleria island is the type locality for pantellerite, an iron and alkali-rich rhyolite. The eruptive products outcropping in the island fall in a mafic end member (mildly alkaline basalt) and a felsic end member (metaluminous trachytes and pantellerites). A key event in the volcanological history of the island is the Green Tuff eruption the sole ignimbrite at Pantelleria compositionally zoned from crystal-poor pantellerite at the base to crystal-rich trachyte at the top. We experimentally investigated the phase relations of the pantelleritic end member AI = 1.8 (agpaitic index = molar ratio Na2O+K2O/Al2O3) and trachyte end member AI = 1.05 of the Green Tuff eruption. The intensive varia…
Eruptive paroxysms at Stromboli: an experimental simulation of pre-eruptive conditions of "yellow pumice"
Role of oxygen fugacity on the solubility of chlorine in peralkaline magmas.
Geologia e geomofologia dell’isola di Pantelleria: il settore di Cala Tramontana-Cala Levante
Melt inclusion study on the pantelleritic plinian eruption of the Green Tuff, Pantelleria Island.
Pantelleria Island is the type locality for the peralkaline rhyolitic rocks called pantellerites. In the last 50 ka, after the Plinian, caldera-forming, Green Tuff eruption, volcanic activity at Pantelleria consisted of effusive and mildly explosive eruptions which mostly vented inside and along the rim of the caldera producing silicic lava flows, lava domes and poorly dispersed pantelleritic pumice fall deposits. During the last two decades, a wealth of studies focused on melt inclusions in pantellerite magmas, all converging in underlying the H2O-rich character of these melts together with high contents of halogens. Recent study on the volatile content of pantellerites from Pantelleria yi…