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The evacuated-tube collector (ETC) for solar heat production is one of the most efficient systems to convert Sun energy into usable energy. Unfortunately, some technological barriers are still present in solar-thermal heat systems that limit the use of these technologies to decarbonize processes. An important obstacle is the requirement for heat at stable temperatures, which is not always achievable by solar fields, e.g. variable sky. For that reason, in this work, we studied the phase-change materials embedded in the ETC to keep stable the water temperature for a short period (minutes, hours). In this study, carnauba wax was used as a sustainable phase-change material (PCM), to avoid the use of PCM based on hydrocarbon waxes. The PCM has been packaged using a polyethylene bag inserted into an ETC with heat-pipe technologies and tested. The collector has been tested outdoors under solar irradiation and under shading conditions. The experimental results show that is possible to detect a sensible effect of the PCM on the temperature using 4 kg of carnauba wax while there is an important effect on the temperature stabilization using 9 kg of PCM. Using 9 kg of the PCM, we observed a stability of the outlet water temperature at 65°C for 30 minutes under shading conditions.

SUMMARY We provide new results from a controlled-source seismic experiment on the deepest part of the Val Sesia crust–mantle section of the Ivrea–Verbano zone (IVZ) in the Italian Alps. The IVZ is a tilted, almost complete section through the continental crust and exposes gabbros and peridotites in the structurally deepest level, coinciding with high-resolution gravity anomalies imaging the Ivrea geophysical body. The seismic experiment SEIZE (SEismic imaging of the Ivrea ZonE) was conducted along two crossing profiles: an NNE-SSW profile of ∼11 km length and an E-W profile of ∼16 km length. 432 vibration points were recorded with 110 receivers resulting in 24 392 traveltime picks. Inversion methods using Markov chain Monte Carlo techniques have been used to derive an isotropic 3-D P-wave velocity model based on first break traveltimes (refracted phases) from controlled source seismic data. Resulting seismic P-wave velocities (Vp ) range from 4.5 to 7.5 km s−1, with an expected general trend of increasing velocities with depth. A sharp velocity change from low Vp in the West to high Vp in the East marks the Insubric Zone (ISZ), the Europe–Adria plate boundary. The most prominent feature of the 3-D tomography model is a high-velocity body (Vp increases from 6 to 7.5 km s−1) that broadens downwards. Its pointy shape peaks the surface East of Balmuccia at a location coincident with the exposed Balmuccia peridotite. Considering rock physics, high-resolution gravity and other geophysical data, we interpret this high-velocity body as dominantly composed of peridotite. The dimension of this seismically imaged peridotite material is far bigger than interpreted from geological cross-sections and requires a revision of previous models. The interpretation of ultramafic bodies in the IVZ as fragments of mantle peridotites interfingered in the crust during pre-Permian accretion is not supported by the new data. Instead, we revive a model that the contact between the Balmuccia peridotite and the Permian mafic magmas might represent a fossil continental crust–mantle transition zone.

The Ivrea-Verbano Zone (IVZ) is the westernmost sector of the Southern Alps. It is constituted by granulite-to-amphibolite-facies continental crust representing the basement of the Adria plate. The IVZ contains many orogenic mantle peridotites. The largest mantle bodies are aligned along the Insubric Line at the lowest stratigraphic units, in contact with mafic-ultramafic crustal intrusives. Mantle bodies in the central and southern sectors of IVZ are spinel lherzolites with spinel dunites and variable amount of clinopyroxenite, websterite and subordinate anhydrous/hydrous gabbroic bodies (e.g. the Baldissero, Balmuccia, Premosello peridotites). Conversely, modally-metasomatised spinel harzburgites with large dunite bodies and phlogopite-and-amphibole-bearing websterites (e.g. the Finero peridotite) crop out in the northern IVZ.The constant association of the IVZ mantle peridotites with High-T shear zones suggests that none of them was emplaced into the crust by mantle diapirism. Alternative hypotheses involve emplacement at the crustal level at the onset of the Mesozoic extensional regime or tectonic addition to accretionary wedges of Paleozoic subduction zones. Recent gravimetric and seismic data converge in indicating that high-density rocks are very close to the surface near the Insubric Line, thus supporting the possibility that the largest mantle peridotites may be a direct expression of the underlying subcontinental mantle.This contribution focuses on new field, petrographic, geochemical and geochronological data, to address some relevant issues, such as the nature of the spinel lherzolite (refractory residue vs. refertilised mantle), the origin of pyroxenites and gabbros, the relationships with the associated crustal intrusives and the record of Mesozoic tectono-magmatic events.The final goal is to provide new insights into the geodynamic evolution of the mantle bodies and the mantle-crust systems at the Laurasia-Gondwana margin, defining in particular how the mantle heterogeneity acquired during Paleozoic may have governed the rifting process of the Adria margin in Jurassic times.

The stable presence of humans in the Alps dates back to the Bronze Age and peaked in the mid-19th century, deeply shaping the landscape and allowing the co-evolution of numerous plant and animal species. Since the 1950s, socio-economic changes have led to the gradual depopulation of mountain areas, and the consequent abandonment of traditional agro-pastoral activities. The rupture of the long-established balance between man and nature has triggered a process of transition, further exacerbated and accelerated by climate change. The Belmont Forum project ABRESO (Abandonment and rebound: Societal views on landscape and land-use change and their impacts on water and soils) started in 2021 and aims at advancing the understanding of mitigation and adaptation strategies to environmental change, through an international partnership involving five countries (the United States, France, Italy, Japan and Taiwan). Italy contributes to the project with three case studies: Gran Paradiso National Park, Val Grande National Park and the Tesino highlands are investigated in the Italian Alps. Using an interdisciplinary approach, the project aims to study the impact of the abandonment of traditional activities on ecosystem services provisioning, such as biodiversity conservation and soil sustainability, as well as the actual perception of the ongoing environmental changes by different stakeholders and its subsequent integration into local land management practices and policies. The land use and land cover change occurring due to land abandonment can have profound implications in the critical zone (CZ), inducing changes in soil, vegetation, carbon fluxes and water resources. This project integrates the natural and social sciences approaches to study the evolution of ecosystems in response to these factors. More specifically, advanced techniques that integrate Earth Observation, biogeochemical analyses and socio-economic investigation are used in the Italian sites to understand in which extent geo-biophysical and social landscapes reciprocally interact. The environmental variables collected for ecosystem monitoring and to study and upscale the ongoing dynamics in the CZ include snow cover and phenology parameters, soil organic carbon, and land use change maps extracted from time series of satellite imagery, validated via in situ measurements. Then, the observed processes will be compared to the perception of different stakeholders (local population, policy makers, tourists, business keepers, etc.) to unveil new insights into the way land use change in the mountain areas influence and is influenced by the local land management practices and policies.

Despite the structural complexity of the Alps at numerous scales, geological and geophysical investigations have respectively mapped and imaged tremendous amounts of information near the surface and at depth. However, there is an inherent gap between the two sets of approaches, leaving the middle and lower crust poorly constrained. This has been one of the main motivations to initiate the ICDP project DIVE (Drilling the Ivrea-Verbano zonE), in which three geological sites of the Ivrea-Verbano Zone will be explored through scientific drilling. In this zone, near-complete sections of the continental crust are exposed at the surface, and with careful geological preparation and geophysical site surveys we have targeted three areas with a great potential of further discoveries during DIVE. Almost all physical and chemical properties will be characterized on the recovered rock core samples, in borehole logging investigations, and additional surveys around each site. Taken together, these should cover a large range of spatial scales covering at least 6 orders of magnitude (mm to km), investigate structures and their variations in bulk properties within the lower crust, and the transition to mantle rocks in an unprecedented way. The interdisciplinary approach not only allows to correlate numerous geophysical and petrological properties, but with modelling it will also allow to investigate the causative relationships. The detailed aims, preparatory steps, as well as the current status of project DIVE, will be presented at the conference. By that time, drilling of the first hole is expected to start near Ornavasso, followed by a second hole in Megolo (both in Val d’Ossola). For the third site near Balmuccia, which is planned for later, site survey results will be presented.

Copper oxides have recently emerged as promising precursor catalyst materials demonstrating enhanced reactivity and selectivity towards C2 and C3 products like ethylene, ethanol, and n-propanol generated from the direct electro-reduction reaction of CO2 (denoted as CO2RR). Advanced operando X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) and Raman spectroscopy were employed to probe the potential-dependent changes of the chemical states of Cu species in the Cu oxide foams (referred to as CuxO) before and during the CO2RR. This complementary and holistic approach of ‘bulk’- and surface-sensitive techniques demonstrates that the electro-reduction of CuxO foams into metallic Cu is completed before hydrocarbon (e.g., ethylene, ethane) and alcohol (e.g., ethanol, n-propanol) formation sets in. There are, however, substantial differences in the potential dependence of the oxide reduction when comparing the ‘bulk’ with the respective ‘surface’ processes. Only in the very initial stage of the CO2RR, the reduction of the Cu oxide precursor species is temporarily superimposed on the production of CO and H2. Complementary identical location (IL) SEM analysis of the CuxO foams prior to and after the CO2RR reveals a significant alteration in the surface morphology caused by the appearance of smaller Cu nanoparticles formed by the reduction process of CuxO species.

Dyke swarms intruding the mantle–continental crust transition of the Adria plate as documented by the Ivrea-Verbano Zone (IVZ, Southern Alps) represent a unique opportunity to investigate the evolution of mantle melts from Late Paleozoic to Mesozoic in the post-collisional Variscan realm. Thus, we present new petrological and geochemical data of dyke swarms cropping out in the Finero Phlogopite Peridotite mantle unit. Dykes are from a few cm to >1 m thick and cut at a high angle the mantle foliation.The dyke swarms are composed of cumulus phlogopite-bearing amphibole peridotite, hornblendite, diorite and anorthosite. Many dykes are composite, showing variable proportions of melanocratic and leucocratic layers. Volatiles overpressure during the late magmatic stage is testified by plastic flow and development of a porphyroclastic structure by deformation of early cumulates and by the widespread segregation of a fine-grained mica matrix. The dyke swarms show mineralogical and geochemical features varying between two end-member series.A dyke series is characterized by Al-rich pargasite (Al2O3 up to 18 wt.%) and phlogopite, associated with apatite, calcite, sulphides and sometimes sapphirine. The amphiboles show i) large LILE and LREE contents, ii) negative Nb, Ta, Zr and Hf anomaly and iii) isotopic oxygen composition heavier than the mantle interval, which support the occurrence of recycled continental crust components in the parent melts and impart an overall “orogenic” affinity.The second series mainly consists of Al-poorer pargasite, phlogopite and albite (An 8-10), associated with apatite, monazite, ilmenite, zircon, Nb-rich oxides and carbonates. Mineral compositions and assemblages indicate that the parent melts were strongly enriched in Fe, Na, H2O, P and C. Amphiboles are still enriched in LILE and LREE, but show extreme enrichments in Nb, Ta, Zr and Hf. As a whole, the petrochemical features point to an “anorogenic” alkaline affinity. Zircons from the “anorogenic” dykes are mostly anhedral, with homogenous internal structure or sector zoning. The strongly positive εHft (average of +10) of zircons and the Sr isotopic composition of amphiboles (0.7042) point to a derivation of such “anorogenic” melts from mildly enriched mantle sources. Concordant 206Pb/238U zircon ages for “anorogenic” dykes vary from 221 ± 9 Ma to 192 ± 8 Ma. Some dykes show both “orogenic” and “anorogenic” affinities, thus recording different pulses of mantle melts and metasomatic overprinting. As a whole, the dyke swarms show a transition from “orogenic” to “anorogenic” affinity indicating re-opening of dykes’ conduits for the melt ascending, pointing to a progressive change of the mantle sources of the Mesozoic magmatism of the Southern Alps.

The Ivrea-Verbano Zone (IVZ) located in the Italian Alps is known as one of most complete archetypes of continental crust–upper mantle section on Earth (e.g. Pistone et al., 2017). Because of its accessibility at the surface it can be used as natural laboratory to improve the understanding of the crust–mantle transition zone. Several geophysical observables indicate the presence of mantle rocks (high density, high seismic velocity) in the shallow sub-surface (~ 1 km), commonly known as the “Bird’s Head” or Ivrea body (Berckhemer, 1968; Diehl et al., 2009; Scarponi et al., 2021). The project SEIZE images and characterizes the shallow upper crust at the Balmuccia site (Italy) providing depth, extent and shape of the outcropping Ivrea body as well as its rock properties. Our tomographic study covers the crust down to about 3 km depth, while seismic reflection imaging is possible down to 6 km depth or deeper. With SEIZE we contribute to the comprehensive ICDP Drilling program in the Ivrea-Verbano ZonE (DIVE, www.dive2ivrea.org).To tackle this task, a controlled source (vibroseis) seismic experiment was carried out in the region around Balmuccia in October 2020. The seismic survey comprised two crossing profiles with a total length of 28 km which ran along (NNE-SSW) and across (W-E) the Balmuccia peridotite. In total, 432 vibro points were acquired with a nominal distance of ~60 m which were recorded using a fix-spread (110 receivers, ~250 m spacing) and a roll-along setup (330 receivers, ~20 m spacing).To obtain a structural image of the shallow upper crust various seismic techniques are applied: The fix-spread data set is used to recover the velocity structure down to 3 km depth. By using a 3D Markov chain Monte Carlo travel time tomography a shallow, distinct high velocity body is imaged in 3D near Balmuccia, at the proposed drill site. Reflection seismic processing is applied to the roll-along data set. However, the difficult terrain setting (deep mountain valleys) results in complex wave propagation that is challenging for conventional processing methods (e.g. static and dynamic corrections, CDP stacking). Therefore, pre-stack migration techniques are applied enabling the imaging of steeply dipping structures.

The ICDP DIVE project (www.dive2ivrea.org) is aimed at addressing fundamental questions on the nature of the lower continental crust and its transition to the mantle, in a first phase through two drillings in the Ivrea Verbano zone (IVZ). The IVZ, considered the world's best outcrop of lower crustal continental rocks, is the exposed part of the Ivrea Geophysical Body (IGB), a major high gravity and high seismic velocity anomaly studied since the 1960s and strongly related to Western Alps structural and tectonic history. Beneath the IVZ the Moho possibly reaches very shallow depth (locally ~1±1 km b.s.l.), making this site unique all over the World.The two proposed drillings will start in the 2022 in Val D’Ossola: the first in Ornavasso and the second in Megolo, 7 km apart from each other. The assemblage of the two will constitute the most complete record of lower continental crust. Physical and chemical data systematically collected downhole as well as along drill cores will be combined and compared with local/regional geophysical and geological surveys. Within this frame and scope, a dedicated seismographic network named DIVEnet has been planned to monitor local earthquakes and operation-related seismic activity.Starting from summer 2021 the survey and seismic station deployment started to have all stations running by January 2022. So far 10 seismographic stations provided by INGV and University of Lausanne have been installed within a 15 km maximum distance from the mid-point between the two drilling sites and recording in continuous mode (100 sps). One of the seismometers will be housed in the first completed borehole while the second one is being drilled. Given that the area is characterized by low natural local seismicity and low seismic stations density, having a long time record of background activity and background noise, including the period before and after the drilling activities’ initiation, is of crucial importance. The acquisition and first elaboration of seismic data have been actively included in the routine work at INGV.

Modelling of geophysical data is often subject to choices made by the researcher undertaking the work. The level of structural complexity in the model, the bounds on parameters imposed by a priori knowledge, the thoroughness and efficiency in exploring the parameter space may all lead to bias in determining what the best fitting models can be.To avoid bias from our own ideas in constraining the subsurface shape of a given density anomaly, we hereby invite anyone interested to create their own models. This is planned by sharing the same gravity data measured in the field, the same digital elevation model, the main features of the local geological maps, and bounds on the encountered rock density values. These data will be shared openly, in the form of a modelling challenge: each participating researcher or group is expected to submit their solution(s). All these will be compared during a dedicated workshop, ultimately resulting in a joint publication.The target of this modelling challenge is the world-famous Balmuccia peridotite body (45.84°N, 8.16°E) in the Ivrea-Verbano Zone (IVZ). Here mantle rocks are naturally exposed at the surface, in the broader context of the IVZ, a middle- to lower crustal terrain along the Europe-Adria plate boundary’s eastern side. The surface exposure of the Balmuccia peridotite is ~ 4.4 km N-S by 0.6 km E-W, with outcrop elevation changes exceeding 1000 m. About 150 new gravity data points have been measured within a radius of 3 km from the centre of the peridotite body, along more or less accessible paths and slopes. The measurements have been carried out with a Scintrex CG-5 relative gravimeter, tied to a reference point, and all points located via differential GPS with typical vertical precision of a few cm. Farther away regional gravity data is available at few km spacing.Beyond the modelling challenge, the interest in constraining the subsurface shape of the Balmuccia peridotite body is its future target role in the ICDP DIVE continental drilling project (www.dive2ivrea.org).

The Jurassic Chenaillet ophiolite in the Western Alps consists of a gabbro–mantle association exhumed to the seafloor through detachment faulting and partly covered by basaltic lavas. One of the Chenaillet gabbroic bodies includes mylonites that are transected by a network of felsic veins, thereby testifying to the interplay of ductile shearing and magma emplacement. The deformed gabbros preserve clinopyroxene porphyroclasts of primary magmatic origin, which are typically mantled by amphibole (titanian edenite) and minor secondary clinopyroxene. Titanian edenite and secondary clinopyroxene also occur as fine-grained syn-kinematic phases locally associated with fine-grained plagioclase. The felsic veins are made up of anorthite-poor plagioclase and minor titanian edenite. Geothermometric investigations document that the ductile gabbro deformation and the crystallization of the felsic veins occurred at 765 ± 50 °C and 800 ± 55 °C, respectively. With respect to undeformed counterparts, the deformed gabbros are variably enriched in SiO2 and variably depleted in Mg/(Mg + Fetot2+) and Ca/(Ca + Na). In addition, the deformed gabbros show relatively high concentrations of incompatible trace elements such as rare earth elements (REE), Y, Zr and Nb. The felsic veins are characterized by low Mg/(Mg + Fetot2+) and Ca/(Ca + Na), high SiO2 and high concentrations of incompatible trace elements. Relict clinopyroxene porphyroclasts from the deformed gabbros display a rather primitive, mid-ocean ridge-type geochemical signature, which contrasts with the trace element fingerprint of titanian edenite from both the deformed gabbros and the felsic veins. For instance, titanian edenite typically has relatively high REE abundances, with chondrite-normalized REE patterns characterized by a pronounced negative Eu anomaly. A similar trace element signature is shown by secondary clinopyroxene from the deformed gabbros. Amphibole from both the deformed gabbros and the felsic veins displays high F/Cl values. We show that the SiO2-rich hydrous melts feeding the felsic veins were involved in the high-temperature gabbro deformation and that melt–gabbro reactions led to major and trace element metasomatism of the deforming gabbros.

There is debate to what degree mid-ocean ridge basalts (MORB) can be used to infer the composition of the sub-ridge mantle and whether the upper mantle contains components that are difficult to recognize by observations on MORB alone. Here we report trace element and isotope data on a fossil mantle section exposed in the ophiolitic Lanzo South massif, Italy. Our findings show the existence of clinopyroxenes in geochemically depleted melt-infiltrated harzburgites with an extreme radiogenic Hf-isotopic composition but MORB-like Nd isotopic compositions. The simplest way of explaining the depleted trace elements in combination with the decoupled isotopic compositions is that the harzburgites were infiltrated by a melt with isotopic compositions inherited from an anciently (>1 Ga) depleted source. The existence of melts from ultra-depleted sectors of the asthenosphere allows constraining of the configuration of the heterogeneities in the sub-ridge mantle. The parallel arrays in Hf–Nd isotope composition space of different Mid-Ocean ridge segments imply the ubiquitous presence of anciently depleted residual mantle as the matrix in which more enriched components occur in pockets.

A mineralogical, major, LA-ICP-MS trace element mineral chemistry and bulk-rock geochemical study of juvenile samples of the Mercato, Avellino, Pompeii and Pollena eruptions, collected in stratigraphically and volcano- logically well-characterized sections of the Somma-Vesuvius stratovolcano (Roman Magmatic Province), along with reference data on the 1944 CE and the Pomici di Base eruptions, highlights the compositional variability of bulk-rock and glass from leucite phonotephrite to garnet-bearing phonolite. The latter products have extreme fractionation of trace elements (e.g., La/Ybn = 126, Zr/Y = 89, Zr/Hf =78, Nb/Ta = 40; Th/U = 2.3), very low Sc, V, Y, HREE and very high As, Tl, Cs, Pb, Th and U. The Pomici di Base products, older than the eruptions described above, range from leucite-bearing shoshonites to trachytes, are devoid of garnet and belong to an independent liquid-line-of-descent, having also different fractionation between trace elements (e.g., La/Ybn = 15; Zr/Y = 12.4, Zr/Hf = 50, Nb/Ta = 15.6; Th/U = 3 in the Pomici di Base trachytes). A marked chemical variability of the observed phases is found. The geochemistry of garnet, amphibole, clinopyroxene and other phases shows wide variations of concentrations and elemental ratios (e.g., La/Ybn up to 520 in the sadanagaite coexisting with garnet). The magmatic evolution is dominated by low-pressure, oxidized, nearly closed-system fractional crystallization of clinopyroxene, plagioclase, leucite, ±magnetite, ±biotite, ±olivine and apatite in the transition tephrite-phonotephrite, and of potassic sanidine (±hyalophane), Fe-clinopyroxene, melanite garnet ±Fe-amphibole in the transition tephriphonolite-phonolite. Mineralogic and geochemical evidence and model- ling points out the existence of independent, zoned magma batches throughout the activity of the stratovolcano, which possibly started to crystallize at similar depths. The Somma-Vesuvius magmas thus evolved in shallow independent reservoirs with respect to those of the neighbouring volcanic complexes (Campi Flegrei, Ischia) as shown, for instance, by the contrasting compositional trends of clinopyroxene and amphibole, and have very limited evidence of crustal contamination (and/or carbonate assimilation).

The Mid-Triassic emplacement of shoshonitic magmas at the NE margin of the Adria plate in concomitance with extensional/transtensional tectonics is one of the most intriguing and peculiar aspects typifying the geodynamic evolution of the Western Tethyan realm. Although often hypothesized, the link between this magmatic event and the metasomatised Southern Alps Sub-Continental Lithospheric Mantle (SCLM) has never been constrained.Geochemical and petrological analyses of lavas, dykes and ultramafic cumulates belonging to the shoshonitic magmatism of the Dolomites, coupled with pre-existing data on peridotite massifs (i.e. Finero, Balmuccia, Baldissero), were used to reconstruct the evolution of the Southern Alps SCLM between Carboniferous and Triassic. According to our model, a metasomatised amphibole + phlogopite-bearing spinel lherzolite, similar to the Finero phlogopite peridotite and likely generated by interaction between a depleted mantle and slab-derived components during the Variscan subduction, was able to produce magmas with orogenic-like affinity during Mid-Triassic. In this context, partial melting degrees of ca. 5-7% were required for producing primitive SiO2-saturated to -undersaturated melts with shoshonitic affinity (87Sr/86Sri = 0.7032-0.7058; 143Nd/144Ndi = 0.51219-0.51235; Mg #~ 70; ~1.1 wt% H2O). As testified by the H2O content in mineral phases from the Finero phlogopite peridotite (Tommasi et al., 2017), the modelled Mid-Triassic fertile lithospheric mantle could have been able to preserve a significant enrichment and volatile content (600-800 ppm H2O) for more than 50 Ma, i.e. since the Variscan subduction-related metasomatism. During the Mid-Triassic partial melting event, the modelled Finero-like mantle exhausted the subduction-related signature inherited during the Variscan subduction. Around 20 Ma later, the same lithosphere portion was affected by an asthenospheric upwelling event related to the Late Triassic-Early Jurassic opening of the Alpine Tethys (Casetta et al., 2019).Casetta, F., Ickert, R.B., Mark, D.F., Bonadiman, C., Giacomoni, P.P., Ntaflos, T., Coltorti, M., 2019. The alkaline lamprophyres of the Dolomitic Area (Southern Alps, Italy): markers of the Late Triassic change from orogenic-like to anorogenic magmatism. Journal of Petrology 60(6), 1263-1298.Tommasi, A., Langone, A., Padrón-Navarta, J.A., Zanetti, A., Vauchez, A., 2017. Hydrous melts weaken the mantle, crystallization of pargasite and phlogopite does not: Insights from a petrostructural study of the Finero peridotites, Southern Alps. Earth and Planetary Science Letters 477, 59-72.

Although often speculated, the link between the Middle Triassic shoshonitic magmatism at the NE margin of the Adria plate and the subduction-related metasomatism of the Southern Alps Sub-Continental Lithospheric Mantle (SCLM) has never been constrained. In this paper, a detailed geochemical and petrological characterization of the lavas, dykes and ultramafic cumulates belonging to the shoshonitic magmatic event that shaped the Dolomites (Southern Alps) was used to model the composition and evolution of the underlying SCLM in the time comprised between the Variscan subduction and the opening of the Alpine Tethys. Geochemical models and numerical simulations enabled us to define that 5–7% partial melting of an amphibole + phlogopite-bearing spinel lherzolite, similar to the Finero phlogopite peridotite, can account for the composition of the primitive Mid-Triassic SiO2-saturated to -undersaturated melts with shoshonitic affinity (87Sr/86Sri = 0.7032–0.7058; 143Nd/144Ndi = 0.51219–0.51235; Mg # ~ 70; ~1.1 wt% H2O). By taking into account the H2O content documented in mineral phases from the Finero phlogopite peridotite, it is suggested that the Mid-Triassic SCLM source was able to preserve a significant enrichment and volatile content (600–800 ppm H2O) for more than 50 Ma, i.e. since the slab-related metasomatism connected to the Variscan subduction. The partial melting of a Finero-like SCLM represents the exhaustion of the subduction-related signature in the Southern Alps lithosphere that predated the Late Triassic-Early Jurassic asthenospheric upwelling related to the opening of the Alpine Tethys.

Processes of crystal-mush remobilization by mafic magma recharges are often related to the outpouring of large volumes of silicic melt during caldera-forming eruptions. This occurred for the Campanian Ignimbrite (CI) eruption (Campi Flegrei, Italy), which produced a voluminous trachy-phonolitic ignimbrite in southern-central Italy about 40 ka ago. We focussed on the proximal-CI deposits at San Martino that are composed of a main sequence of early-erupted, crystal-poor units and a late-erupted (post-caldera collapse) crystal-rich Upper Pumice Flow Unit (UPFU). Detailed micro-analytical geochemical data were performed on glasses and crystals of pyroclasts from these deposits and coupled with Sr-Nd isotopic measurements on glasses. Results show that the CI eruption was fed by two distinct melts for the early-erupted units and the late UPFU, respectively. The glasses of the early-erupted units have negative Eu anomalies and show more evolved compositions and higher Nd isotope ratios than those of the UPFU, which have positive Eu/Eu*. The magmas of the early units formed the main volume of eruptible melt of the CI reservoir, and are interpreted as having been extracted from cumulate crystal-mush without a vertical geochemical gradient within the magma reservoir. The data indicate that the generation of the distinctive UPFU melts involved the injection of a new batch of mafic magma into the base of the CI reservoir. The mafic magma allowed heating and reactivation of the CI crystal-mush by melting of low-Or sanidines (+/− low-An plagioclases), leaving high-An plagioclases and high-Mg# clinopyroxenes as residual phases and a crystal-mush melt, made of 20% of the initial mush interstitial melt (with a composition similar to the early-erupted units) and 80% of sanidine melt. When the mush crystallinity was sufficiently reduced, the mafic magma was able to penetrate into the reactivated crystal-mush, mixing with variable proportions of crystal-mush melt and generating cooler hybrid melts, which underwent further crystallization of high-Or sanidine at variable degrees (10–25%). Finally, possibly a short time before the eruption, the UPFU magmas were able to mix and mingle with the crystal-poor eruptible melts still persisting in the CI reservoir at the time of UPFU emission. We suggest that the complex mechanisms described for the magma evolution feeding the CI eruption may occur whenever a crystal-mush is reactivated by new mafic magma inputs

The Ivrea-Verbano Zone in the Italian Alps represents one of the most complete and best-studied cross-sections of the continental crust. Here, geological and geophysical observations indicate the presence of the Moho transition zone at shallow depth, possibly as shallow as 3 km in the location of Balmuccia in Val Sesia. Correspondingly, the Ivrea-Verbano Zone is a primary target for assembling data on the deep continental crust as well as for testing several hypotheses regarding its formation and evolution. Within the context of a project submitted to the International Continental Scientific Drilling Program (ICDP), the Drilling the Ivrea-Verbano zonE (DIVE) team proposes to establish three drill holes across pertinent structures within the Ivrea-Verbano Zone. Two of the planned drill holes, each with a length of ~1000 m, are within Val d’Ossola and target the Pre-Permian lower and upper section of the lower crust. The third proposed drill hole, with a length of ~4000 m, is targeting the lower most crust of the Permian magmatic system of the Ivrea-Verbano Zone in the Val Sesia, close to the Insubric Line. Combined, the three drill holes will compose a complete section of the lower crust and the Moho transition zone, and will reveal the associated structural and composition characteristics at different scales.To bridge across the range of spatial scales and to support the drilling proposal, we have carried out active seismic surveys using an EnviroVibe source in the Val d’Ossola. These surveys combined 2D transects (in-line) with the simultaneous collection of short cross-lines, and spatially varied source points, to collect sparse 3D data with a preferential CMP coverage across strike. This survey geometry was largely controlled by environmental considerations and access for the vibrator. Accordingly, 2D profiles, both in-line and cross-line, have been processed using crooked-line geometries, which include CMPs from the 3D infill.The very high acoustic impedance contrast of the Quaternary valley infill sediments with respect to the predominant metapelitic and gabbroic lower crustal rocks, as well as the highly attenuative nature of the sediments, were both beneficial and problematic. The former enables mapping of the valley structure, while the latter largely prevents the detection of low-amplitude reflections from within the underlying lower crustal rocks.Here, we present the latest results of these seismic reflection surveys and discuss the observations with respect to the prevailing structure and the planning of the drilling operations. Beyond the specific objectives pursued in this study, our results have important implications with regard to the acquisition and processing of high-resolution seismic reflection data in crystalline terranes and their capacity for resolving complex, steeply dipping structures.

An experimental geothermal monitoring, performed on the ground source heat pump (GSHP) system running in a nearly zero energy building (NZEB), has been realized in the protected hydrothermal area of Ponte Arche (Italian Alps), at the request of the competent geological authority. The scope is to assess if a thermal interference could appear between the exploitation of the shallow underground by borehole heat exchangers (BHEs) and nearby thermal baths. Currently, in this area an absolute prohibition for shallow geothermal applications is in force, the area is categorized “potentially subject to geothermal manifestations”. However, in light of new geological and hydrogeological knowledge, supported by long-term monitoring, the protection criterion and constraint geometry could be reviewed. Preliminary to the experimental geothermal monitoring, a detailed ground investigation campaign was performed, including: a geological setting overview based on existing cartography, one continuous core drilling, three downhole geophysical surveys, one thermal response test (TRT). The monitored parameters comprehend the underground temperature at different depths, the outdoor air temperature, and the ground-side heat flow of the GSHP. The collected data are presented and discussed, including considerations about the underground sustainability of the BHE field, and about the real heating and cooling operation of the GSHP ground-side.

In this work, we aim to develop a Zn-based metal foam catalyst with very large specific area suitable for efficient CO production. Its manufacture is based on the dynamic hydrogen bubble template method that consists of the superposition of metal deposition and hydrogen evolution at the solid-liquid interface. We employed Cu ions in the Zn2+-rich electroplating bath as foaming agent. The concentration of Cu as foaming agent was systematically studied and an optimized Zn94Cu6 foam alloy was developed, which, to the best of our knowledge, is the most selective Zn-based CO2 electrocatalyst toward CO in aqueous bicarbonate solution (FECO = 90% at -0.95 V vs reversible hydrogen electrode). This high efficiency is ascribed to the combination of high density of low-coordinated active sites and preferential Zn(101) over Zn(002) texturing. X-ray photoelectron spectroscopy investigations demonstrate that the actual catalyst material is shaped upon reduction of an oxide/hydroxide-terminating surface under CO2 electrolysis conditions. Moreover, intentional stressing by oxidation at room conditions proved to be beneficial for further activation of the catalyst. Identical location scanning electron microscopy imaging before and after CO2 electrolysis and long-term electrolysis experiments also showed that the developed Zn94Cu6 foam catalyst is both structurally and chemically stable at reductive conditions.

The Ivrea–Verbano Zone is the most complete, time-integrated crust–upper mantle archive in the world. It is a unique target for assembling data on the deep crust and the Moho transition zone and testing several hypotheses of formation, evolution, and modification of the continental crust through space and time across the Earth. The ICDP workshop Drilling the Ivrea–Verbano zonE (DIVE), held in Baveno, Italy, from 1 to 5 May 2017, focused on the scientific objectives and the technical aspects of drilling and sampling in the Ivrea–Verbano Zone at depth. A total of 47 participants from 9 countries with a wide variety of scientific and/or drilling expertise attended the meeting. Discussion on the proposed targets sharpened the main research lines and led to working groups and the necessary technical details to compile the full drilling proposal. The participants of the workshop concluded that four drilling operations in the Val Sesia and Val d'Ossola crustal sections represent the scientifically most promising solution to achieve the major goals within DIVE to unravel the physico-chemical properties and architecture of the lower continental crust towards the crust–mantle (Moho) transition zone.

Potential-dependent CO2 reduction reactions (CO2RR) were carried out on technical Cu mesh supports that were stepwise modified by (i) electrodeposition of dendritic Cu catalysts under mass transfer control of Cu(II) ions followed by (ii) an extra 3 h thermal annealing at 300 °C in air. The initial electrodeposition of dendritic Cu activates the technical supports for highly efficient formate production at low overpotentials (FEFormate = 49.2% at −0.7 V vs RHE) and in particular for C–C coupling reactions at higher overpotentials (FEC2H4 = 34.3% at −1.1 V vs RHE). The subsequent thermal annealing treatment directs the CO2RR product selectivity toward multicarbon alcohol formation (ethanol/EtOH and n-propanol/n-PrOH) resulting into a total Faradaic yield of FEalcohol = 24.8% at −1.0 V vs RHE (FEEtOH = 13%). Moreover, the EtOH and n-PrOH production rate of 155.2 μMLelectrolyte–1 cmECSA–2 h–1 and 101.4 μMLelectrolyte–1 cmECSA–2 h–1 (normalized with respect to the electrolyte volume and the electrochemically a...

Highly porous 3D Cu skeletons (sponges) modified by electropolishing, thermal annealing, and foam electrodeposition have been studied as catalysts for the electrochemical conversion of CO2 with a particular emphasis on C2 products formation. These catalyst materials appear to be promising for future applications where gaseous CO2 reactants can be transported through the 3D catalyst thereby tuning the mean residence time of reaction intermediates inside the catalyst, which crucially influences the final product distribution. In particular, the annealed skeleton (300 °C, 12 h) and the one modified by Cu foam electrodeposition show profound activities toward C2 product formation (C2H4, C2H6) with faradaic efficiencies reaching FEC2 = 32.3% (annealed skeleton sample, −1.1 V vs RHE) and FEC2 = 29.1% (electrodeposited sample, −1.1 V vs RHE), whereas the electropolished Cu skeleton remains largely inactive for both the C1 and the C2 pathway of hydrocarbon formation. This effect is discussed on the basis of resid...

A detailed petrochemical investigation of the peridotites from the Mt. Pollino area (Basilicata, Southern Italy) allowed to provide the first comprehensive reconstruction of the evolution and geodynamic setting of ophiolitic mantle from the Southern Apennines. These mantle peridotites firstly acquired strongly-refractory modal and chemical compositions consistent with large degrees of partial melting (≥ 23%). This process was presumably assisted by concomitant injection of melt increments rising from deeper levels of the mantle column, as suggested by relatively large Al and Fe contents of Ol, Opx and Sp. The porous flow ascent of melt increments produced by deeper near-fractional melting continued after the end of the partial melting, as recorded by precipitation of disseminated clinopyroxene out of thermal and chemical equilibrium with the other rock-forming minerals. The Pollino mantle sequence locally experienced reheating associated to a new episode of porous flow migration of melts with REE composition approaching that of N-MORB. The petrological evolution recorded by the peridotites of Mt. Pollino, their high equilibrium T (up to 1100 °C) and the absence of pyroxenites show remarkable analogies with modern abyssal peridotites, pointing to an intra-oceanic setting of the Jurassic Ligurian Tethys for this mantle sequence. According to the present knowledge about the Southern Apennines, the abyssal-like peridotites with the associated terrigenous sediments and continental crustal rocks were incorporated in the Ligurian Accretionary Complex and reached HP/LT conditions during a subduction event starting in Upper Oligocene, to be later exhumed in the Tortonian. The results of this study strongly support the existence of significant differences in terms of geodynamic evolution between Southern and Northern Apennines. © 2017 Elsevier B.V.

International audience; A detailed microstructural, geochemical and geochronological study was performed on zircon grains from plagioclase-rich dioritic dykes discordantly intruded within meta-diorites/gabbros forming the External Gabbro unit of the Finero Mafic Complex (Italian Alps). This unit is exposed as part of a near complete crustal section spanning from mantle rocks to upper crustal metasediments (Val Cannobina, Ivrea–Verbano Zone, Italy). The leucocratic dykes consist mainly of plagioclase (An18–24Ab79–82Or0.3–0.7) with subordinate amounts of biotite and spinel defining melanocratic layers. Zircon and corundum are common accessory phases. Both the dykes and the surrounding meta-diorites/gabbros show evidence of ductile deformation under amphibolite-facies conditions.Zircon grains/fragments (up to 2 mm in length) occur as porphyroclasts surrounded by fine-grained plagioclase within the leucocratic domains and may occur within the melanocratic layers completely or partially surrounded by biotite and spinels. Fractures are common within zircon, define networks and have associated displacements occasionally and/or they can be filled by secondary minerals.Cathodoluminescence (CL) images reveal that zircon grains from the leucocratic layers show relicts of primary magmatic (i.e. oscillatory and or sector) zoning generally related with the crystal shapes or crystallographic orientation, whereas those from the melanocratic domains do not. In both cases, zircon shows secondary CL features, i.e. mosaic-like textures, due to deformation. EBSD maps confirmed a profuse mosaic texture, resulting in an internal misorientation of ca. 10°, generally associated with fractures. Locally, zircon shows clear evidence of crystal-plastic deformation at the edges, with a gradual misorientations of up to 12°, suggesting an origin prior fragmentation.Trace elements and U–Pb analyses were carried out by LA-ICP-MS directly on petrographic thin sections. Such in situ investigations revealed a strong correlation between internal zircon structures, chemistry, U–Pb isotope ratios and mylonitic fabric.U–Pb data return highly discordant and variable ages. The 206Pb/238U ages may range from ca. 297 to 198 Ma within the same zircon grain from the leucocratic layers, whereas 206Pb/238U younger than 250 Ma were systematically obtained from zircon within the melanocratic layers. The 206Pb/238U data younger than ca. 240 Ma from zircon grains within the leucocratic layers were obtained from narrow axial stripes observed in CL images and oriented parallel or at low-angle with respect to the foliation planes. These stripes are characterized by an overall HREE, Y, U and Th enrichment possibly reflecting deformation of the grain in presence of interstitial fluid phases. Combining U–Pb data, microstructure and zircon CL features, we suggest a multistage evolution of the dykes whereby the melanocratic layers are the result of a Late Permian metasomatic event promoting modification of the pre-existing mineral assemblage of the (Late Carboniferous–Early Permian?) dykes and deformation and partial resetting of zircon porphyroclasts. This has important implications in the geology of the Ivrea–Verbano Zone because, having the dyke intruded the External Gabbro unit before Triassic (probably during Carboniferous–Permian), the latter cannot be considered a Triassic intrusion. At least part of the External Gabbro unit is Carboniferous–Permian as the other mafic bodies of the Ivrea–Verbano Zone.

The petrologic study of olivine-hosted melt inclusions (MIs) from alkaline primary Cenozoic basalts of Northern Victoria Land (Antarctica) provide new insights on the role of volatiles in the onset of rift-related magmatism. The concentration of volatile species (H2O, CO2, F, Cl) have been determined by Secondary Ion Mass Spectrometry (SIMS) on a selection of MIs which have been previously re-homogenized at high pressure and temperature conditions in order to avoid any heterogeneity and reducing the H diffusion. The least differentiated MIs vary in composition from basanitic to alkaline basalts, analogously to what is found in McMurdo volcanics, while their volatile concentrations reach up to 2.64 wt% H2O, 3900 ppm CO2, 1377 ppm F and 1336 Cl. Taking into account the most undegassed MIs a H2O/(H2O+CO2) ratio equal to 0.88 was determined, which in turn brings the CO2 content in the basanitic melt with the highest water content up to 8800 ppm.Major and trace element melting modelling indicate that basanite and alkali basalt composition can be reproduced by 3 and 7% of partial melting of an amphibole-bearing spinel lherzolite respectively. Assuming a perfect incompatible behavior for H2O and CO2 these melting proportions allow to constrain the water and CO2 contents in the mantle source in the range 780-840 and 264-273 ppm respectively. The resulting CO2/Nb, CO2/Ba and H2O/Ce ratio are lower than those estimated for Depleted MORB Mantle (DMM), suggesting that the NVL Cenozoic alkaline magmatism could be originated by an enriched mantle source composed by a range from 70% to 60% of Enriched Mantle (EM) and from 30% to 40% of Depleted Morb Mantle (DMM).A global comparison of fluid-related, highly incompatible and immobile/low incompatible elements such as Li, K, Cl, Ba, Nb, Dy and Yb allow to put forward that the prolonged (~500 to 100 Ma) Ross subduction event played a fundamental role in providing the volatile budget into the lithospheric mantle before the onset of the Cenozoic continental rifting.

The Doldrums transform system offsets the Equatorial Mid Atlantic Ridge by similar to 630 km at 7-8 degrees N. This transform system consists of four intra-transform spreading centers (ITRs) bounded by five transform faults. The northern-most ITR is linked to the MAR axis by a similar to 180 km-long transform. Here, during two R/V A. N. Strakhov expeditions (S06 and S09), mantle peridotites were dredged along the transverse and median ridge of the transform, across the western flank of the ITR valley. Residual harzburgites were mainly sampled along the northern Doldrums transform valley, whereas plagioclase-bearing peridotites showing evidence for melt-rock interaction characterize the ITR domain. Petrological and geochemical observations reinforced by geochemical modelling are used to define the behaviour of trace elements during melt extraction and melt-rock reaction in our rocks. Results suggest that residual peridotites derive from mantle rocks that have undergone a degree of partial melting up to 12%, with melting likely starting at the transition of garnet-spinel stability fields, whereas peridotites which suffered melt-rock reactions have been divided into two types: (i) pl-impregnated peridotites, formed by migration of melts at high porosity and high melt-rock ratio; and (ii) refertilized peridotites, generated at reduced porosity, when small fractions of the same percolating melt crystallized clinopyroxene and minor plagioclase. We suggest that the refertilizing agent was a melt highly depleted in incompatible trace elements, in turn produced by an ultra-depleted mantle source. This mantle experienced previous degrees of melt extraction at the ridge axis, before being transposed laterally along the transform where it melted a second time during the opening of the intra-transform spreading segment. (C) 2020 Elsevier B.V. All rights reserved.

This study presents a new petrological–geochemical data set for the Monte Capio and Alpe Cevia mafic–ultramafic sequences, which are exposed in the deepest levels of the Ivrea–Verbano Zone. These sequences are composed of a peridotite core, with dunite in the center, mantled by minor orthopyroxene-dominated pyroxenites and subordinate hornblende gabbronorites. Amphibole is ubiquitous in the peridotites and the pyroxenites (≤ 15 vol % and 10–40 vol %, respectively), and the peridotite–pyroxenite associations are frequently crosscut by amphibole-rich (45–90 vol %) veins/dykes showing sinuous-to-sharp planar boundaries towards host rocks. The whole-rock Mg# [100 × Mg/(Mg + Fetot2+)] decreases from the peridotites to the pyroxenites and the crosscutting amphibole-rich dykes (84–81, 80–77, and 73–66, respectively), consistently with the Mg# variations shown by included orthopyroxene, clinopyroxene, and amphibole. Olivine has relatively low forsterite and NiO amounts (84–78 mol % and ≤ 0.14 wt%), and spinel is characterized by low Cr# [100 × Cr/(Cr + Al)] of 7–24. The anorthite content of plagioclase varies from 91 to 88 mol% in plagioclase-bearing pyroxenites to 91–75 mol% in amphibole-rich dykes. The chondrite-normalized REE patterns of amphibole from peridotites and pyroxenites show nearly flat MREE–HREE, no evident Eu anomaly, and LREE that are slightly depleted to slightly enriched with respect to MREE. Amphibole from the amphibole-rich veins/dykes exhibits slight LREE depletion. Whole-rock and amphibole separates show substantial variations in initial Nd–Sr isotopic compositions (e.g., whole-rock eNd calculated at 290 Ma ranges from − 0.3 to − 4.7), irrespective of the rock-type and of incompatible element amphibole compositions. We propose that the Monte Capio–Alpe Cevia dunites formed by cooling of magma lenses that intruded the lowermost continental crust of the Ivrea–Verbano Zone. The chemically evolved signature of the dunites documents earlier crystallization of chemically primitive dunites at lower levels, or olivine fractionation within the dunites during melt ascent. Associated pyroxene-bearing peridotites show a magmatic evolution ruled by reaction of a melt-poor crystal mush with migrating melts relatively rich in SiO2 and H2O, which developed orthopyroxene and amphibole at the expenses of olivine ± clinopyroxene. These migrating melts may be reconciled with those feeding the crosscutting amphibole-rich veins/dykes, whose compositions suggest formation by chemically evolved H2O-rich basalts with an arc-type incompatible trace-element fingerprint. Unraveling the origin of the Monte Capio–Alpe Cevia pyroxenites is hampered by the complex open-system magmatic evolution, which also included assimilation of material released by basement metasediments and/or involvement of primary melt batches with different compositions.

Pyroxenites are diffuse in fertile mantle peridotites and considered an important component in the mantle source of oceanic basalts. They are rarely documented in abyssal and ophiolitic peridotites representing residual mantle after melt generation, and few studies defining their origin are to date available. We present a field-based microstructural and geochemical investigation of the pyroxenite layers associated with depleted peridotites from the Mt. Maggiore ophiolitic body (Corsica, France). Field and petrographic evidence indicate that pyroxenite formation preceded the melt-rock interaction history that affected this mantle sector during Jurassic exhumation, namely (1) spinel-facies reactive porous flow leading to partial dissolution of the pyroxenites, and (2) plagioclase-facies melt impregnation leading to [plagioclase + orthopyroxene] interstitial crystallization. Pyroxenes show major element compositions similar to abyssal pyroxenites from slow-spreading ridges, indicative of magmatic segregation at pressures higher than 7 kbar. Both the parental melts of pyroxenites and the melts involved in the subsequent percolation were characterized by Na2O-poor, LREE-depleted compositions, consistent with unaggregated melt increments. This implies that they represent the continuous evolution of similarly depleted melts leading to different processes (pyroxenite segregation and later melt-rock interaction) during their upward migration. To support the genetic relation and the continuity between the formation of pyroxenites and the subsequent melt-rock interaction history, we modeled all the documented processes in sequence, i.e.: (1) formation of single-melt increments after 6% mantle decompressional fractional melting; (2) high-pressure segregation of pyroxenites; (3) spinel-facies reactive porous flow, (4) plagioclase-facies melt impregnation. The early fractionation of pyroxenites leads to a decrease in pyroxene saturation that is necessary for the subsequent reactive porous flow process, without any significant change in the melt REE composition.

The Central Atlantic Magmatic Province (CAMP) is a large igneous province (LIP) composed of basic dykes, sills, layered intrusions and lava flows emplaced before Pangea break-up and currently distributed on the four continents surrounding the Atlantic Ocean. One of the oldest, best preserved and most complete sub-provinces of the CAMP is located in Morocco. Geochemical, geochronologic, petrographic and magnetostratigraphic data obtained in previous studies allowed identification of four strato-chemical magmatic units, i.e. the Lower, Intermediate, Upper and Recurrent units. For this study, we completed a detailed sampling of the CAMP in Morocco, from the Anti Atlas in the south to the Meseta in the north. We provide a complete mineralogical, petrologic (major and trace elements on whole-rocks and minerals), geochronologic (40Ar/39Ar and U–Pb ages) and geochemical set of data (including Sr–Nd–Pb–Os isotope systematics) for basaltic and basaltic–andesitic lava flow piles and for their presumed feeder dykes and sills. Combined with field observations, these data suggest a very rapid (

International audience; A group of ultramafic xenoliths hosted in Cenozoic hypabyssal rocks from Harrow Peaks (northern Victoria Land, Antarctica) show textural and geochemical features far removed from anything previously observed in mantle xenoliths of this region and elsewhere in Antarctica. They consist of spinel-bearing lherzolites and harzburgites, characterised by a predominant equigranular texture with orthopyroxene modal contents remarkably higher in lherzolites (18-26 volume%) with respect to the harzburgite (13 vol%), one orthopyroxenite, and three composite xenoliths. The latter are formed by an olivine-dominant assemblage (olivine > 70%) crosscut by large monomineralic (amphibole or clinopyroxene) or bimineralic (amphibole + clino-pyroxene) veins. No significant correlation was observed between the lithology and the Fo content (90.21-82.81) of olivine, suggesting that these rocks could be derived from a cumulus process. The presence of the orthopyroxenite suggests that the inferred melt/s from which they stemmed was close (or even above) to silica saturation. Based on major and trace-element mineral/melt and mineral/mineral equilibrium modelling, these rocks were formed by progressive extraction of olivine from a high magnesium (Mg = 72)-high temperature (~ 1300 °C) melt following a very short fractionation line. Thermobaro-metric results indicate the stationing of Harrow Peaks cumulates in the P field of 1.3 ± 0.2 (dunites)-0.5 ± 0.2 (orthopy-roxenite) GPa. These values well match the crust/mantle boundary (Moho) of the region. The combined geochemical and petrological data suggest that Harrow Peaks melts could be related to the initial stage of the Jurassic Ferrar magmatism, whose deep cumulates were subsequently affected by the Cenozoic alkaline metasomatism, widely detected in the northern Victoria Land lithosphere and responsible for the formation of the late amphibole/amphibole + clinopyroxene veins.

In this work, we aim to develop a Zn-based metal foam catalyst with very large specific area suitable for efficient CO production. Its manufacture is based on the dynamic hydrogen bubble template method that consists of the superposition of metal deposition and hydrogen evolution at the solid-liquid interface. We employed Cu ions in the Zn

The Itasy is a Pleistocene-Holocene volcanic field in central Madagascar, located to the west of the Ankaratra volcanic complex. It comprises scoria cones and lava domes (>120), with associated pyroclastic fall and mafic lava flows, covering an area of ab. 400 km(2). The last volcanic episodes probably dated ca. 6000-7100 y BP; warm springs and geysers are active. The juvenile samples comprise a peculiar, almost bimodal, rock suite ranging from potassic leucite-kaersutite-bearing basanites, tephrites and phonotephrites, to benmoreites and titanitehauyne-bearing trachyphonolites (MgO from 9-10 wt% to 0.1 wt%). These rocks show continuous and overlapping variations in the bulk-rock and phase composition (olivine, clinopyroxene, amphibole, feldspar, leucite, haflyne, nepheline, oxides, apatite, titanite, glass and other accessories). The basanites have homogeneous isotopic composition (Sr-87/Sr-86 = 0.70366-0.70378, Nd-143/(144) Nd = 0.51274-0.51277, Pb-206/Pb-204 = 18.7-18.9, (207)pb/(204)pb = 15.53-15.56; Pb-208/Pb-264 = 38.89-39.01), and a marked enrichment in the most incompatible elements (LILE and HFSE reach 100-215 times primitive mantle). These features are consistent with low degrees of partial melting of a volatile-, LILE- and HFSE-rich, amphibole-bearing peridotitic mantle induced by uplift during an E-W-directed extensional regime, as is found in central Madagascar. The marked changes in the geochemical composition, and small variations of the Sr-Nd-Pb isotopes in the trachyphonolites (Sr-87/Sr-86 = 0.70425-0.70446, Nd-143/Nd-144 = 0.51266-0.51269, Pb-206/Pb-204 = 18.18-1839, Pb-207/Pb-264 = 15.49-15.51; Pb-208/Pb-204 = 3838-39.57) with respect to basanites and tephrites point to a limited amount of crustal contamination by the relatively low-Pb-206/Pb-204, low-Nd-143/Nd-144, high-Sr-8.7/Sr-86 Precambrian basement rocks (of Middle Archean to Late Proterozoic age), and highlight the geochemical effects of titanite and anorthoclase removal on the trace element fractionation trends, a feature also shown in the trace element composition of the phenocrysts in trachyphonolites. (C) 2018 Elsevier B.V. All rights reserved.

In this work, we have studied the relationships between mass concentration and unit formula of amphibole using 114 carefully selected high-quality experimental data, obtained by electron microprobe (EMP) + single-crystal X-ray structure refinement (SREF) +/- secondary-ion mass spectrometry (SIMS) analyses, of natural and synthetic Li-free monoclinic species belonging to the Ca and Na-Ca subgroups, and 75 Li-free and Mn-free C2/m end-members including oxo analogs of Ca amphiboles. Theoretical considerations and crystal-chemical driven regression analysis allowed us to obtain several equations that can be used to: (1) calculate from EMP analyses amphibole unit-formulas consistent with SREF +/- SIMS data, (2) discard unreliable EMP analyses, and (3) estimate O-W(2-) and Fe3+ contents in Li-free C2/m amphiboles with relatively low Cl contents (

This study reports petrostructural observations in the pargasite and phlogopite-bearing Finero peridotite massif (Italian Western Alps), which suggest that the pervasive foliation in this massif was formed by deformation concomitant with percolation of hydrous Si-rich melts: (1) diffuse contacts, but systematic parallelism between the pyroxenitic layers and the foliation of the peridotite (2) strong shape and crystal preferred orientations (SPO and CPO), but subhedral or interstitial shapes and weak intracrystalline deformation of the hydrous phases, (3) CPO, but interstitial shapes of the pyroxenes, (4) very coarse olivine grain sizes, which are correlated to the olivine abundance, and (5) elongated shapes, but weak intracrystalline deformation, and extremely weak and highly variable CPO of olivine. The pervasive deformation of the Finero peridotite occurred therefore under conditions that allowed coexistence of H2O-CO2-bearing melts, pargasite, and spinel, that is, temperatures of 980-1080 degrees C and pressures