Relationships between deformation and mixing processes in lava flows: a case study from Salina (Aeolian Islands,Tyrrhenian Sea)

 The massive unit of a lava flow from Porri volcano (Salina, Aeolian Islands) displays many unusual structures related to the physical interaction between two different magmas. The magma A represents approximately 80% of the exposed lava surface; it has a crystal content of 51 vol.% and a dacitic glass composition (SiO₂=63–64 wt.%). The magma B has a basaltic-andesite glass composition (SiO₂=54–55 wt.%) and a crystal content of approximately 18 vol.%. It occurs as pillow-like enclaves, banding, boudin-like and rolling structures which are hosted in magma A. Structural analysis suggests that banding and boudin-like structures are the result of the deformation of enclaves at different shear strain. The linear correlation between strain and stratigraphic height of the measured elements indicates a single mode of deformation. We deduce that the component B deformed according to a simple shear model. Glass analyses of the A–B boundary indicate that A and B liquids mix together at high shear strain, whereas only mingling occurs at low shear strain. This suggests that the amount of deformation (i.e. forced convection) plays an important role in the formation of hybrid magmas. High shear strain may induce stretching, shearing and rolling of fluids which promote both forced convection and dynamical diffusion processes. These processes allow mixing of magmas with large differences in their physical properties. Received: 15 July 1995 / Accepted: 30 May 1996     

A new look at the relationship between activity, dynamo number and Rossby number in late-type stars

The correlation between stellar activity, as measured by the indicator Δ R _HK, and the Rossby number Ro in late-type stars is revisited in light of recent developments in solar dynamo theory. Different stellar interior models, based on both mixing-length theory and the full spectrum of turbulence, are used in order to see to what extent the correlation of activity with Rossby number is model dependent, or otherwise can be considered universal. Although we find some modest model dependence, we find that the correlation of activity with Rossby number is significantly better than with rotation period alone for all the models we consider. Dynamo theory suggests that activity should scale with the dynamo number. A current model of the solar dynamo, the so-called interface dynamo, proposes that the amplification of the toroidal magnetic field by differential rotation (the ω -effect) and the production of the poloidal magnetic field from toroidal by helical turbulence (the α -effect) take place in different, adjacent layers near the base of the convection zone. A new scale analysis based on the interface dynamo shows that the appropriate dynamo number does not depend on the Rossby number alone, but also depends on an additional dimensionless factor related to the differential rotation. This leads to a new interpretation of the correlation between activity and Rossby number, which in turn leads to some conclusions about the magnitude of differential rotation in the dynamo layers of late-type main-sequence stars.     

Slope dynamics of Lake Albano (Rome,Italy): insights from high resolution bathymetry

New detailed data about the morphology of the submerged slopes of Lake Albano (Rome, Italy) have been collected by a sonar multibeam survey financed by the Italian Department of Civil Protection. These data allow for investigation of the subaqueous slope dynamics of the lake, which partially fills a volcanic depression, and the elucidation of the relationships between subaqueous and subaerial slope processes. Subaerial, submerged and combined subaerial/submerged landslide‐related morphologies were detected around the inner slopes of the lake. In the submerged slopes, several gravity‐induced landforms were recognized: landslide scar areas, landslide accumulations, erosional chutes and channels, block fields, isolated blocks, scarps and slope breaks. An attempt to evaluate the state of activity of the submerged slopes was carried out by taking into consideration the relative freshness of some selected landforms. Interpretation of bathymetric data, as well as direct surveys of the subaerial slopes, was used to assess the morphometric features and interpret the type of movement of the landslides. We propose a comprehensive classification based on the landslide's size and type of movement. We recognized rock fall/topples, debris flows, rock slides and slump, complex rock slides/channelled flows and debris slide and slump. The volume of the main landslides ranged between 10¹ and 10³ m³, while a few rock and debris slides have volumes ranging between 10³ and 10⁵ m³. Two large palaeo‐landslides with volumes on the order of 10⁶ m³ were identified in the southern and northern part of the lake, respectively. Velocities of the recognized landslides range from rapid to extremely rapid. Two main landslide hazard scenarios have been depicted from the results of the integrated analysis of both subaerial and submerged gravity‐induced landforms. The most hazardous scenario involves extremely rapid large volume events (>10⁶ m³) that could, if they interacted with water, induce catastrophic tsunamis. Copyright © 2009 John Wiley & Sons, Ltd.     

Latest Precambrian to Early Cambrian U–Pb zircon ages of augen gneisses from Calabria (Italy), with inference to the Alboran microplate in the evolution of the peri-Gondwana terranes

In situ U–Pb dating of zircons from five samples of Calabrian augen gneisses shows that their protoliths are Latest Precambrian to Early Cambrian in age (562 ± 15, 547 ± 7, 540 ± 4, 539 ± 16 and 526 ± 10 Ma), and contain Archaean (3.1 Ga), Palaeoproterozoic (1.7–2.4 Ga) and Neoproterozoic (0.6–0.9 Ga) inheritance. Geochemical signature of augen gneisses is typical of high-K calc-alkaline post-collisional magmatism. Their Sr–Nd isotopic compositions [0.7093 < (⁸⁷Sr/⁸⁶Sr)_i < 0.7139; −3.2 < ɛ_Nd(t) < −5.4; 1.5 < T _DM < 1.7 Ga] indicate the involvement of a crustal component in significant proportions. The Calabrian augen gneisses have, therefore, to be distinguished from the orthogneisses of Sardinia and northern Algeria, and from the porphyroids of Sicily, which are Middle Ordovician. By contrast, the Calabrian augen gneisses show a close similarity to the Pan-African post-collisional granitoids of the northern edge of the West African craton (e.g. the Moroccan Anti-Atlas). This suggests a peri-Gondwana origin and corroborates previous palaeogeodynamic reconstructions attributing the Alboran microplate to the northern margin of the West African craton.     

Environmental impacts of household appliances in Europe and scenarios for their impact reduction

Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint “appliances” for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative – i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale).     

Application of an in-plane/out-of-plane interaction model for URM infill walls to dynamic seismic analysis of RC frame buildings

Experimental tests have shown that unreinforced masonry (URM) infill walls are affected by simultaneous loading in their in-plane and out-of-plane directions, but there have been few attempts to represent this interaction in nonlinear time history analysis of reinforced concrete (RC) buildings with URM infill walls. In this paper, a recently proposed macro-model that accounts for this interaction is applied to the seismic analysis of RC framed structures with URM infill walls representative of Mediterranean building stock and practices. Two RC framed structures that are representative of low and mid-rise residential buildings are analysed with a suite of a bidirectional ground motions, scaled to three different intensities. During the analyses, the in-plane/out-of-plane interaction is monitored, showing that cracking of the infills occurs predominantly by in-plane actions, while failure occurs due to a combination of in-plane and out-of-plane displacements, with the out-of-plane component usually playing the dominant role. Along the frame height, the bottom storeys are generally the most damaged, especially where thin infill walls are used. These results are consistent with observations of damage to URM infill walls in similar buildings during recent earthquakes.     

Sample return of interstellar matter (SARIM)

The scientific community has expressed strong interest to re-fly Stardust-like missions with improved instrumentation. We propose a new mission concept, SARIM, that collects interstellar and interplanetary dust particles and returns them to Earth. SARIM is optimised for the collection and discrimination of interstellar dust grains. Improved active dust collectors on-board allow us to perform in-situ determination of individual dust impacts and their impact location. This will provide important constraints for subsequent laboratory analysis. The SARIM spacecraft will be placed at the L2 libration point of the Sun–Earth system, outside the Earth’s debris belts and inside the solar-wind charging environment. SARIM is three-axes stabilised and collects interstellar grains between July and October when the relative encounter speeds with interstellar dust grains are lowest (4 to 20 km/s). During a 3-year dust collection period several hundred interstellar and several thousand interplanetary grains will be collected by a total sensitive area of 1 m². At the end of the collection phase seven collector modules are stored and sealed in a MIRKA-type sample return capsule. SARIM will return the capsule containing the stardust to Earth to allow for an extraction and investigation of interstellar samples by latest laboratory technologies.     

Virtual Versus Real Jets: New Clues from the Hubble Space Telescope

During past years high angular (<1″) resolution imaging has provided useful information about the propagation of “real” jets. Recently, in addition, the spectrograph Hubble's Space Telescope Imaging spectrograph (STIS) on board the Hubble Space Telescope (HST) has finally allowed us to test the magneto-centrifugal paradigm for the jet launching. I present results from HST/STIS spectra at 0.″1 resolution of small-scale jets from T Tauri stars in their initial 140 AU (1″). The jet morphology, kinematics and excitation in different velocity intervals are derived, from which we calculate mass and momentum fluxes. Even more interestingly, we find indications for rotation around the symmetry axis in the peripheral regions of the flow. The investigated component of the wind appears to originate in the disk at a distance of 0.5-2 AU from the star, and it extracts at least 60% of the inner disk angular momentum. These results confirm for the first time the validity of the magneto-centrifugal approach for the jet launching, and constitute a benchmark to test models and simulations. In the near future, near-infrared (NIR) interferometry with AMBER/VLTI and with the LBTI will permit to observe the jet engine down to 0.1 AU from the source, where the acceleration of the jet takes place.     

Vesta's mineralogical composition as revealed by the visible and infrared spectrometer on Dawn

The Dawn spacecraft mission has provided extensive new and detailed data on Vesta that confirm and strengthen the Vesta–howardite–eucrite–diogenite (HED) meteorite link and the concept that Vesta is differentiated, as derived from earlier telescopic observations. Here, we present results derived by newly calibrated spectra of Vesta. The comparison between data from the Dawn imaging spectrometer—VIR—and the different class of HED meteorites shows that average spectrum of Vesta resembles howardite spectra. Nevertheless, the Vesta spectra at high spatial resolution reveal variations in the distribution of HED‐like mineralogies on the asteroid. The data have been used to derive HED distribution on Vesta, reported in Ammannito et al. (2013), and to compute the average Vestan spectra of the different HED lithologies, reported here. The spectra indicate that, not only are all the different HED lithologies present on Vesta, but also carbonaceous chondritic material, which constitutes the most abundant inclusion type found in howardites, is widespread. However, the hydration feature used to identify carbonaceous chondrite material varies significantly on Vesta, revealing different band shapes. The characteristic of these hydration features cannot be explained solely by infalling of carbonaceous chondrite meteorites and other possible origins must be considered. The relative proportion of HEDs on Vesta's surface is computed, and results show that most of the vestan surface is compatible with eucrite‐rich howardites and/or cumulate or polymict eucrites. A very small percentage of surface is covered by diogenite, and basaltic eucrite terrains are relatively few compared with the abundance of basaltic eucrites in the HED suite. The largest abundance of diogenitic material is found in the Rheasilvia region, a deep basin, where it clearly occurs below a basaltic upper crust. However, diogenite is also found elsewhere; although the depth to diogenite is consistent with one magma ocean model, its lateral extent is not well constrained.     

Geometric and kinematic complexities in the Marche-Abruzzi external zones (Central Apennines,Italy)

In the Central Apennines (Italy) three major domains can be recognized: the Umbria and Marche pelagic domains and the Lazio-Abruzzi carbonate platform. Their Mesozoic-Tertiary sequences are separated by major low-angle thrust systems, which superpose the Umbria domain onto both the Marche and Lazio-Abruzzi domains, the Lazio-Abruzzi platform onto the Marche sequence, and all of them onto the Apulia foreland.From Lias to Cretaceous times the Lazio-Abruzzi platform was a fault-controlled uplifted domain separating the Umbria basin to the west from the Marche basin to the east, but closed to the north. The Umbria and Marche basins evolved distinctly with the onset of the terrigenous infilling, beginning with the Serravallian-Tortonian «Marnoso-Arenacea» Formation in the inner Umbria basin and with the Messinian-Early Pliocene Laga Flysch in the outer Marche basin. From Tortonian till Early Pliocene times there was a progressive deformation of the Umbria sequence, with its emplacement onto the Lazio-Abruzzi platform, and the deformation of the Lazio-Abruzzi and Marche zones. In Early-Middle Pliocene times, both the Umbria and Lazio-Abruzzi domains were emplaced onto the previously deformed Marche domain, with passive transport of that portion of Umbria stacked on top of the Lazio-Abruzzi platform. The final stages in Middle-Late Pliocene times caused further motion of the Lazio-Abruzzi platform along the arc-shaped Gran Sasso-Morrone thrust front. Folding and thrusting persisted in the outermost zones till Early Pleistocene times.This reconstruction means that in this area the model of a regularly forward migrating fold-thrust belt is not applicable. It also suggests a large northward displacement of the Lazio-Abruzzi platform, whose differential advancement may be dynamically related to a left-lateral discontinuity to the west and a right-lateral discontinuity to the east. According to our interpretation, the left-lateral discontinuity is not coincident with the «Ancona-Anzio» line of the Italian literature, but rather is buried underneath the Umbria stacked sequences.

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Zusammenfassung Der Zentralappennin (Italien) besteht aus drei Hauptbereichen: die pelagialen Gebiete Umbriens und der Marche sowie die Karbon-Platte Latiums und der Abruzzen. Die Formationsgruppen des Mesozoikum-Tertiär dieser drei Gebiete werden durch große Überschiebungsbahnen getrennt, welche die umbrische Zone auf die Zone der Marche sowie Latiums und der Abruzzen schieben, die Zone Latiums und der Abruzzen ihrerseits auf die Formation der Marche und alle zusammen auf das Vorland Apuliens.Die ursprüngliche paleogeographische Struktur der drei Gebiete läßt darauf schließen, daß die Latium-Abruzzen-Platte vom Lias bis zur Kreidezeit eine aktive, erhobene Zone darstellt, die das Umbrische Becken im Westen vom Becken der Marche im Osten trennt, wobei sich die Platte nach Norden hin schließt, was ein Ineinandergreifen der beiden pelagialen Gebiete mit sich bringt. Beide Becken weisen eine getrennte Evolution auf, mit dem Beginn einer terrigenen Zufuhr, bestehend aus der Marnoso-Arenacea-Formation des Serravall-Tortons im Inneren des Umbrischen Beckens und mit dem Laga Flysch des Messin und Unter-Pliozän im äußeren Umbrischen Becken. Vom Torton bis zum Unteren Pliozän hat eine progressive Deformation der Umbrischen Sequenz stattgefunden, die auf dem Gebiete Latiums und der Abruzzen abgelagert wurde, was wiederum zur Deformation in der Zone Latiums und der Abruzzen sowie der Marche führte. Im unteren Mittel-Pliozän wurden sowohl die Formationen Umbriens als auch die der Zonen von Latium und der Abruzzen auf die schon deformierte Formationsgruppe der Marche aufgeschoben, mit nachfolgend passivem Transport des schon auf der Latium-Abruzzen-Platte aufgelagerten Teils der Umbrischen Formation. Die letzten Ereignisse im mittleren Ober-Pliozän führten zu einem weiteren Vorschub der Latium-Abruzzen-Platte längs der bogenförmigen Verwerfungsfront Gran Sasso-Morrone, sowie zu nachfolgenden Falten und Verwerfungen in den äußersten Gebieten bis zum unteren Pleistozän.Diese Rekonstruktion bedeutet vor allen Dingen, daß in diesem Gebiet das Modell einer regelmäßig voranschreitenden Überschiebungsfront nicht anwendbar ist. Sie deutet ferner auf eine große, nordwärts gerichtete Verschiebung der Latium-Abruzzen-Platte hin, deren differenzierter Vorschub dynamisch in Bezug zu einer links-lateralen Verschiebung nach Westen und einer rechts-lateralen Verschiebung nach Osten zu bringen ist. Gemäß unserer Auslegung stimmt die links-laterale Verschiebung nicht mit der «Ancona-Anzio» Linie der einschlägigen italienischen Fachliteratur überein, sondern ist eher unter den überlagernden Sequenzen Umbriens zu suchen.

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Résumé On peut distinguer trois domaines dans la partie centrale des Apennins (Italie): le domaine pélagique des Marches, celui de l'Ombrie et la plate-forme carbonatée du Latium-Abruzzes. Les séries stratigraphiques mésozoïques-tertiaires de ces trois domaines sont séparées par d'importants systèmes de chevauchement qui ont provoqué la superposition du domaine ombrien sur ceux des Marches et du Latium-Abruzzes, la superposition de la plate-forme du Latium-Abruzzes sur la série des Marches, et enfin la superposition de toute la chaîne sur l'avantpays de l'Apulie.Du Lias au Crétacé, la plate-forme du Latium-Abruzzes constituait un domaine soulevé par des failles actives; ce domaine séparait le bassin de l'Ombrie à l'ouest du bassin des Marches à l'est et était limité au nord, permettant ainsi la communication des deux régions pélagiques. Ces deux bassins ont présenté une évolution distincte débutant par un remplissage terrigène; celui-ci est représenté, dans le bassin ombrien plus interne par la Formation Marnoso-Arénacéa (Serravalien-Tortonien), et dans le bassin externe des Marches par la formation du Flysch de la Laga (Messinien-Pliocène inférieur). A partir du Tortonien jusqu'au début du Pliocène, la série ombrienne a subi une déformation progressive, et à été charriée sur le domaine du Latium-Abruzzes, provoquant la déformation de ce dernier, ainsi que du domaine des Marches. Au cours du Pliocène inférieur et moyen, les domaines de l'ombrie et du Latium-Abruzzes ont été charriés sur la série des Marches ainsi déformée, entraînant de ce fait le transport passif de la portion de la séquence ombrienne préalablement charriée sur la plate-forme du Latium-Abruzzes. Plus tard, des mouvements méso- à tardi-pliocènes ont provoqué un dernier charriage de la plate-forme du Latium-Abruzzes le long de l'arc de chevauchement Gran Sasso-Morrone; enfin, les plissements et les charriages ont persisté dans les zones les plus externes jusqu'au Pléistocène inférieur.Cette reconstitution signifie que le modèle d'une chaîne plissée et charriée se déplaçant régulièrement vers l'avant-pays ne peut pas être appliqué à cette région. Elle indique également un vaste déplacement vers le Nord de la plate-forme du Latium-Abruzzes, transport qui peut être dynamiquement mis en relation avec un décrochement sénestre à l'ouest et un décrochement dextre à l'est. Selon notre interprétation, le décrochement sénestre ne coïncide pas avec la ligne «Ancona-Anzio» de la littérature italienne, mais est enterré sous l'édifice charrié de l'Ombrie.

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