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The occurrence of phlogopite and amphibole in mantle ultramafic rocks is widely accepted as the modal effect of metasomatism in the upper mantle. However, their simultaneous formation during metasomatic events and the related sub-solidus equilibrium with the peridotite has not been extensively studied. In this work, we discuss the geochemical conditions at which the pargasite-phlogopite assemblage becomes stable, through the investigation of two mantle xenoliths from Mount Leura (Victoria State, Australia) that bear phlogopite and the phlogopite + amphibole (pargasite) pair disseminated in a harzburgite matrix. Combining a mineralogical study and thermodynamic modelling, we predict that the P–T locus of the equilibrium reaction pargasite + forsterite = Na-phlogopite + 2 diopside + spinel, over the range 1.3–3.0 GPa/540–1500 K, yields a negative Clapeyron slope of -0.003 GPa K–1 (on average). The intersection of the P–T locus of supposed equilibrium with the new mantle geotherm calculated in this work allowed us to state that the Mount Leura xenoliths achieved equilibrium at 2.3 GPa /1190 K, that represents a plausible depth of ~ 70 km. Metasomatic K-Na-OH rich fluids stabilize hydrous phases. This has been modelled by the following equilibrium equation: 2 (K,Na)-phlogopite + forsterite = 7/2 enstatite + spinel + fluid (components: Na2O,K2O,H2O). Using quantum-mechanics, semi-empirical potentials, lattice dynamics and observed thermo-elastic data, we concluded that K-Na-OH rich fluids are not effective metasomatic agents to convey alkali species across the upper mantle, as the fluids are highly reactive with the ultramafic system and favour the rapid formation of phlogopite and amphibole. In addition, oxygen fugacity estimates of the Mount Leura mantle xenoliths [Δ(FMQ) = –1.97 ± 0.35; –1.83 ± 0.36] indicate a more reducing mantle environment than what is expected from the occurrence of phlogopite and amphibole in spinel-bearing peridotites. This is accounted for by our model of full molecular dissociation of the fluid and incorporation of the O-H-K-Na species into (OH)-K-Na-bearing mineral phases (phlogopite and amphibole), that leads to a peridotite metasomatized ambient characterized by reduced oxygen fugacity.

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.

H2O, CO2, F, Cl and S concentrations in olivine-hosted melt inclusions (MI) from Cenozoic alkaline volcanics of Northern Victoria Land (NVL, Antarctica) were determined by Secondary Ion Mass Spectrometry (SIMS). The most undegassed H2O and CO2 values varies from 1.14 to 2.64 wt% H2O and from 2320 to 3900 ppm CO2 for the least differentiated alkaline basalts and basanites, respectively. The same MI have F and Cl contents varying from 471 to 888 and from 474 to 1135 respectively, although some other MI can get up to 1377 of F and 1336 of Cl. A H2O/(H2O + CO2) molar ratios from 0.88 to 0.92 were determined, and taking into account the MI with the highest water content, a CO2 content in the melts up to 4400 and 8800 ppm for basaltic and basanitic compositions were inferred. Assuming that these magmas were produced by about 3 to 7% of partial melting, the volatile content in the mantle sources were estimated and compared with the estimates obtained from amphibole-bearing mantle xenoliths abundantly entrained in the McMurdo basic lavas. The two approaches converge in obtaining the following values: H2O = 1160 ± 436 ppm; CO2 = 304 ± 64 ppm. Some discrepancies are observed for F and Cl, mainly due to the uncertainties in the F and Cl contents of amphibole and its modal content, both parameters spanning a rather large range. The resulting CO2/Nb and CO2/Ba ratios are lower and H2O/Ce higher 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 60 to 70% Enriched Mantle (EM) and from 40 to 30% 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 to the lithospheric mantle before the onset of the Cenozoic continental rifting.

The publication of this special volume is aimed at celebrating the relevant contributions on the comprehension of the Earth's mantle geochemical/geodynamic system, presented and discussed during the three days of the third edition of the "European Mantle Workshop" (Pavia, Italy, 2018). The main topics proposed in the workshop may be reassumed as follows: (1) mineralogical, petrological and geochemical characterization of mantle xenoliths, orogenic peridotites and ophiolitic mantle sections; (2) experimental investigations on the production, migration and emplacement of mantle melts and fluids; (3) geophysical studies and numerical models of the deep mantle; (4) serpentinisation and carbonation of peridotites, and the relationship between microbiology in extreme environments. They trigged considerable discussion, involving a wide audience outside of the speaker list. Some issues became the focus for substantial informative debates on the meaning and significance of different types of data and the interpretative approaches that could yield the best results. Based on these considerations and the titles already proposed by EMAW's participants, we expected that this volume will reflect the range of topics that created the workshop's stimulating debate, offering a collection of thought-provoking papers, for the advances in the comprehension of mantle paradigms.

OBJECTIVES: Inherent technical aspects of pulmonary lobectomy by video-assisted thoracoscopic surgery (VATS) may limit surgeons’ ability to deal with factors predisposing to complications. We analysed complication rates after VATS lobectomy in a prospectively maintained nationwide registry. METHODS: The registry was queried for all consecutive VATS lobectomy procedures from 49 Italian Thoracic Units. Baseline condition, tumour features, surgical techniques, devices, postoperative care, complications, conversions and the reasons thereof were detailed. Univariable and multivariable regressions were used to assess factors potentially linked to complications. RESULTS: Four thousand one hundred and ninety-one VATS lobectomies in 4156 patients (2480 men, 1676 women) were analysed. The median age-adjusted Charlson index of the patients was 4 (interquartile range 3–6). Grade 1 and 2 and Grade 3–5 complications were observed in 20.1% and in 5.8%, respectively. Ninety-day mortality was 0.55%. The overall conversion rate was 9.2% and significantly higher in low-volume centres (

The complex European–Adria geodynamic framework, which led to the formation of the Alpine belt, is considered responsible for the orogenic magmatism that occurred in the Central Alps along the Periadriatic/Insubric Line (late Eocene–early Oligocene) and the anorogenic magmatism that occurred in the Southeastern Alps (late Paleocene–early Miocene). While the subduction-related magmatic activities are, as expected, near convergent margins, the occurrence of the intraplate-related magmatism is still puzzling. Therefore, in this work new geochemical and geochronological data of magmatic products from the Veneto Volcanic Province (VVP, north–east Italy) are provided to constrain the Cenozoic intraplate magmatism of the Southeastern Alps. The VVP is formed by dominant basic–ultrabasic (from nephelinites to tholeiites) magmatic products and by localized acid (latitic, trachytic, and rhyolitic) volcanic and subvolcanic bodies. Trace element patterns and ratios suggest that the mantle source of the alkaline magma types was a garnet lherzolite possibly metasomatised by carbonatitic melts and with residual phlogopite. According to the biostratigraphic records and our new 40Ar/39Ar ages, VVP eruptions occurred in several pulses, reflecting the extensional phases experienced by the Eastern Alpine domain. The volcanism started in the late Paleocene in the western sector of the VVP where activity was widespread also during the Eocene (45.21 ± 0.11 Ma – 38.73 ± 0.44 Ma). In the eastern sector eruptions took place in the early Oligocene (32.35 ± 0.09 Ma – 32.09 ± 0.29 Ma) and in the early Miocene (~23–22 Ma). From the studies so far undertaken, the anorogenic magmatic activity of the VVP was interpreted as resulting from mantle upwellings through slab window(s) following the European slab break-off, which occurred at ~ 35 Ma. However, considering (i) new tomographic images evidencing a continuous subvertical (~ 500 km in depth) slab beneath the Central Alps, and (ii) the onset of magmatic activity in the VVP in the late Paleocene (i.e., before the slab break-off) and its continuation until the Miocene, a better suited geodynamic scenario is required to explain the anorogenic magmatism. The westward rollback of the European slab caused the retreat and steepening of the subducting plate. As a consequence, sub-slab mantle material escaped and upwelled from the front of the slab and created a poloidal mantle flow. The latter induced the breakdown of carbonates in calcareous metasediments and carbonated metabasics within the subducting oceanic slab, providing carbonatitic melts, which could be responsible for the metasomatism of the VVP mantle sources. After that, the poloidal mantle flow also induced (i) the extensional deformation in the overriding Adria microplate, (ii) the decompressional melting of VVP mantle sources, and (iii) the intraplate affinity of the VVP magmatism. During these processes, the Adria microplate also rotated counterclockwise, forming sedimentary basins, and allowing the poloidal mantle flow to affect different portions of the overlying lithosphere, generating syn-estensional magmatism within the VVP.

The petrology of anhydrous peridotite xenoliths hosted in the Cenozoic alkaline volcanic rocks from Handler Ridge (northern Victoria Land, Antarctica) provides new constraints on the characterization of the subcontinental lithospheric mantle beneath the West Antarctic Rift. For most samples, the temperature of equilibration was calculated on the basis of Fe/Mg partitioning among olivine, orthopyroxene, and spinel, at a pressure of 15 kbar. These results revealed a temperature of ∼1030 °C and fO2 ranging from -0.26 to +0.39 with respect to fayalite-magnetite-quartz buffer (δFMQ). Compared with other anhydrous and hydrated mantle xenolith suites occurring in northern and southern Victoria Land, these xenoliths represent the highest-temperature and most-oxidized conditions. On the basis of major-element modeling, we suggest that this portion of the mantle represents a residuum after 7%-18% partial melting. Geochemical and isotopic compositional evidence is indicative of significant metasomatism caused by an alkaline melt almost entirely overprinting the residual peridotite composition within a period of 102-103 yr. © 2017 The Geological Society of America. All rights reserved.

Equilibrium reactions over the sub-solidus MgO-FeO binary, i.e., periclase-like structure (Mg,Fe)O phases, were modelled in the frame of pyrolitic Earth lower mantle via (Mg,Fe)O mixing Gibbs energy as a function of composition, P and T, using quantum mechanical calculations (Hartree-Fock/DFT hybrid scheme), cluster expansion techniques, statistical thermodynamics and chemical equilibrium formalism. We aim to explore how the equilibrium reaction (Mg,Fe)O-products are a source for lower mantle geochemical heterogeneities (e.g., variability of the phases' compositions, phase proportions and density). Iron in Fe-periclase was modelled in both low-spin (LS) and high-spin (HS) state, separately, and the sub-solidus (Mg,Fe)O-system was treated as an open system that exchanges Mg and Fe with the lower mantle, considered as a reservoir. On the basis of our results, LS is the main booster of equilibrium phase changes in the sub-solidus (Mg,Fe)O-system over the lower mantle. The model indicates that the sub-solidus (Mg,Fe)O-system is able to continuously incorporate iron from the reservoir forming equilibrium phases with compositions and proportions that vary over the P-T range 24/1920-80/2530 GPa/K. At higher pressure and temperature, up to 128/3150 GPa/K, the sub-solidus (Mg,Fe)O-system stabilizes a quasi-invariant iron-rich composition [(Mg0.50Fe0.50)O], predominant in terms of phase proportions, and two iron-poor compositions given by (Mg0.10Fe0.90)O and (Mg0.175Fe0.825)O. These theoretical results are in agreement with the compositional variance observed in the lower mantle Fe-periclase from diamond inclusions and are consistent with the frequency of occurrence revealed for the compositions of the natural specimens. The density differences among the equilibrium (Mg,Fe)O-phases increase up to ~1 0%, between 24 and 128 GPa. The calculated bulk Fe/Mg partitioning coefficient between perovskite (here used as a chemical approximation of the reservoir) and Fe-periclase is 0.64 at 24 GPa, then drops to 0.19 at 80 GPa, and becomes quasi-invariant (0.18-0.16) in the lowermost portion of the Earth mantle (~ 80-128 GPa). These values are consistent with those experimentally determined. Altogether our results suggest that Fe-periclase does cause geochemical heterogeneities over the range 24-80 GPa, but it does not give rise to any sharp discontinuity, so that the deepest lower mantle seismic anomalies (i.e., D''-region) do not seem primarily ascribable to the mixing reactivity of the sub-solidus (Mg,Fe)O-system.

A petrological study of two mantle xenolith suites from Northern Victoria Land (NVL) have been carried out in order to characterize a large portion of the lithospheric mantle beneath the West Antartict Rift System from Mt. Melbourne (74°21¿S 164°42¿E) to Handler Ridge (HR) (72°31¿ 167°18¿E). Samples are anhydrous lherzolites, although few harzburgites and wehrlites are also found. GP peridotites vary from protogranular to porphyroclastic in texture, while in HR medium to coarse or fine-grained equigranular texture prevails. Based on mineral major and trace element petrological modeling, this mantle domain may represent a residuum after ~10 to 20% of partial melting. Overprinted on this event at GP there are evidence for the percolation of a tholeiitic and an alkaline melts, most probably affecting the mantle domain in different times. The first event increases the Al2O3 content in opx and cpx and modifies the REE content in cpx, leaving a garnet signature. The good matching with trace element content in cpx phenocryst from Ferrar and Karoo tholeiites allow to ascribe this refertilization event to Jurassic time. The second event is associated with the alkaline Cenozoic magmatism related to the WARS opening and it is responsible for the presence of rare, LREE-enriched, secondary cpx and alkali-rich glassy patches. The mg# values (mg# ol=87.5-91.0) and the high variable cpx HREE contents (YN=1.76-11.45) of the HR reflect a fertile to moderate residual mantle segment. The presence of SiO2-rich glass and rare, trace element-enriched secondary cpx suggest that HR population was also affected by melt interaction, most probably of alkaline affinity. Both HR and GP peridotites are thermal constrained at 950-980 °C, with redox conditions close to the QFM buffer, and the tendency for GP population towards more reduction conditions (~ -1.04 log units below QFM, on average). Compared with hydrated mantle xenoliths from nearby localities, GP and HR xenolith suites present higher T and comparable oxidized conditions.

A petrological study of two mantle xenolith suites from Northern Victoria Land (NVL) have been carried out in order to characterize a large portion of the lithospheric mantle beneath the West Antartict Rift System from Mt. Melbourne (74°21¿S 164°42¿E) to Handler Ridge (HR) (72°31¿ 167°18¿E). Samples are anhydrous lherzolites, although few harzburgites and wehrlites are also found. GP peridotites vary from protogranular to porphyroclastic in texture, while in HR medium to coarse or fine-grained equigranular texture prevails. Based on mineral major and trace element petrological modeling, this mantle domain may represent a residuum after ~10 to 20% of partial melting. Overprintend on this event at GP there are evidence for the percolation of a tholeiitic and an alkaline melts, most probably affecting the mantle domain in different times. The first event increases the Al2O3 content in opx and cpx and modifies the REE content in cpx, leaving a garnet signature. The good matching with trace element content in cpx phenocryst from Ferrar and Karoo tholeiites allow to ascribe this refertilization event to Jurassic time. The second event is associated with the alkaline Cenozoic magmatism related to the WARS opening and is responsible for the presence of rare LREE-enriched, secondary cpx and high alkalies glassy patches. The mg# values (mg# ol = 87.5-91.0) and the high variable cpx HREE contents (YN =1.76-11.45) of the HR reflect a fertile to moderate residual mantle segment. The presence of SiO2-rich glass and rare, trace element-enriched secondary cpx suggest that HR population was also affected by melt interaction, most probably of alkaline affinity. Both HR and GP peridotites are thermal constrained at 950-980 °C, with redox conditions close to the QFM buffer, and the tendency for GP population towards more reduction conditions (~ -1.04 log units below QFM). Compared with hydrated mantle xenoliths from nearby localities, GP and HR xenolith suites present higher T and comparable oxidized conditions.

This study sought to prospectively assess which factors were related to short-term worsening heart failure (HF) leading to or not to hospital admission, in long-term outpatients followed by cardiologists. The subsequent decision-making process was also analyzed. The study population consisted of 2,701 outpatients enrolled in the registry of the Italian Network on Congestive Heart Failure (IN-CHF) and followed by 133 cardiology centers (19% of all existing Italian cardiology centers). Clinical and follow-up data were collected by local trained clinicians; 215 patients (8%) had short-term decompensation (on average 2 months after the index outpatient visit). Multivariate analysis showed that previous hospitalization, long duration of symptoms, ischemic etiology, atrial fibrillation, higher functional class (New York Heart Association classification III to IV), higher heart rate, and low systolic blood pressure were independently associated with HF destabilization. Poor compliance (21%) and infection (12%) were the most frequent precipitating factors, but a precipitating factor was not identified in 40% of the patients. Poor compliance was more common in women, but no other clinical characteristics emerged as being related with a specific precipitating factor. Fifty-seven percent of the patients with a short-term recurrence of worsening HF required hospital admission; infusion treatment with inotropes and/or vasodilators was necessary in 19% of them. Long-term therapy was changed in 48% of the patients. Thus, in ambulatory HF patients, short-term worsening HF can be predicted according to the clinical characteristics on an outpatient basis. Nearly 1/3 of precipitating factors can be prevented. Patient education and avoidance of inappropriate treatment may reduce the number of relapses.

International audience

International audience