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.

In the present work, we report the chemical composition of representative emerald crystals from some of the most important worldwide deposits. Major and trace elements were investigated using Electron Microprobe Analysis (EMPA) and Secondary Ion Mass Spectrometry (SIMS) techniques. Binary, ternary and spider diagrams along with statistical analysis, i.e., Principal Component Analysis (PCA), were used to discriminate each deposit with high reliability. PCA of SiO2, Al2O3, V, Sc, B, Li content identified distinct groups. The use of binary and ternary diagrams contributed to discriminate among emerald crystals from various deposits, which are included in the same clusters of the PCA analysis. In addition, the geochemical features of each group were linked to the geological environment and genetic processes which leaded to emerald formation. In particular, the emeralds related to granitic-pegmatitic intrusions (Type-1) or those occurring in environments controlled by tectonic events (Type-2) were distinguished using the concentrations of major and trace elements. The results of this study can contribute to improve the existing genetic models and classification schemes as well as to identify useful geochemical fingerprints for provenance purposes.

The iconic climate archive of Tenaghi Philippon (TP), NE Greece, allows the study of short-term palaeoclimatic and environmental change throughout the past 1.3 Ma. To provide high-quality age control for detailed palaeoclimate reconstructions based on the TP archive, (crypto)tephra studies of a peat core 'TP-2005' have been carried out for the 0-130 ka interval. The results show that the TP basin is ideally positioned to receive tephra fall from both the Italian and Aegean Arc volcanic provinces. Two visible tephra layers, the Santorini Cape Riva/Y-2 (c. 22 ka) and the Campanian Ignimbrite (CI)/Y-5 (c. 39.8 ka) tephras, and six primary cryptotephra layers, namely the early Holocene El tephra from the Aeolian Islands (c. 8.3 ka), the Campanian Y-3 (c. 29 ka) and X-6 tephras (c. 109.5 ka), as well as counterpart tephras TM-18-1d (c. 40.4 ka), TM-23-11 (c. 92.4 ka) and TM-33-la (c. 116.7 ka) from the Lago Grande di Monticchio sequence (southern Italy), were identified along with repeatedly redeposited Y-2 and CI tephra material. Bayesian modelling of the ages of seven of the primary tephra layers, 60 radiocarbon measurements and 20 palynological control points have been applied to markedly improve the chronology of the TP archive. This revised chronology constrains the age of tephra TM-18-1d to 40.90-41.66 cal ka BP (95.4% range). Several tephra layers identified in the TP record form important isochrons for correlating this archive with other terrestrial (e.g., Lago Grande di Monticchio, Sulmona Basin and Lake Ohrid) and marine (e.g., Adriatic Sea core PRAD 1-2 and Aegean Sea core LC21) palaeoclimate records in the Mediterranean region. (C) 2018 Elsevier Ltd. All rights reserved.

Lithium gradients in plagioclase are capable of recording extremely short-lived processes associated with gas loss from magmas prior to extrusion at the surface. We present SIMS profiles of the 7 Li/ 30 Si ion ratio in plagioclase crystals from products of the paroxysmal sequence that occurred in the period 2011–2013 at Mt. Etna (Italy) in an attempt to constrain the final ascent and degassing processes leading to these powerful eruptions involving basic magma. The observed Li concentrations reflect cycles of Li addition to the melt through gas flushing, and a syn-eruptive stage of magma degassing driven by decompression that finally produce significant Li depletion from the melt. Modeling the decreases in Li concentration in plagioclase by diffusion allowed determination of magma ascent timescales that are on the order of minutes or less. Knowledge of the storage depth beneath the volcano has led to the quantification of a mean magma ascent velocity of ~43 m/s for paroxysmal eruptions at Etna. The importance of these results relies on the application of methods, recently used exclusively for closed-system volcanoes producing violent eruptions, to open-conduit systems that have generally quiet eruptive periods of activity sometimes interrupted by sudden re-awakening and the production of anomalously energetic eruptions.

Replacive mantle dunites are considered to be shallow pathways for extraction of mantle melts from their source region. Dunites offer a unique possibility to unravel the compositional variability of the melts produced in the upper mantle, before mixing and crystal fractionation modify their original signature. This study includes a quantification of H2O, Li and trace elements (Ni, Mn, Co, Sc, V, Ti, Zr, Y and HREE) in olivine from large replacive dunite bodies (>20m) within a mantle section exposed in the Western Italian Alps (Lanzo South ophiolite). On the basis of olivine, clinopyroxene and spinel compositions, these dunites were previously interpreted to be formed by melts with a MORB signature. Variations in Ni, Mn, Co and Ca contents in olivine from different dunite bodies suggested formation by different melt batches. The variable H2O and Li contents of these olivines agree with this idea. Compared to olivine from residual peridotites and olivine phenocrysts in MORB (both having H2O <5ppm; Li >1ppm), the Lanzo South dunite olivine has high H2O (18–40ppm) and low Li (0.35–0.83ppm) contents. Geochemical modelling suggests that the dunite-forming melts were produced by low melting degrees of a mixed garnet-pyroxenite-peridotite mantle source, with a contribution of a garnet pyroxenite component variable from 20 to 80%. The Lanzo dunites experienced migration of melts geochemically enriched and mainly produced in the lowermost part of the melting region. Extraction of enriched melts through dunite channels are probably characteristic of cold thermal regimes, where low temperatures and a thick mantle lithosphere inhibit mixing with melts produced at shallower depths.

Wilancookite, ideally (Ba, K, Na)(8)(Ba, Li,square)(6)Be24P24O96 center dot 32H(2)O, is a new mineral species from the Lavra Ponte do Piaui complex granitic pegmatite, Minas Gerais, Brazil. It occurs as tiny dodecahedral {1 1 0} crystals, deposited on moraesite fibres. Associated primary minerals are albite, montebrasite, Li-bearing micas, cassiterite, elbaite and quartz, while the secondary phosphate association contains fluorapatite, childrenite, eosphorite, zanazziite, greifenstenite, guimaraesite, ushkovite, saleeite and moraesite. The mineral is transparent and colourless, with a vitreous lustre; it is non-fluorescent, brittle, and its streak is white. The estimated Mohs hardness is 4-5, and the calculated density is 3.05 g/cm(3). Wilancookite is isotropic, colourless, non-pleochroic, with n = 1.560(2) (measured under lambda = 590nm). Electron- and ion-microprobe analyses give (in wt%): P2O5 36.19, SiO2 0.04, Al2O3 0.41, BaO 34.65, Na2O 0.09, K2O 0.32, BeO 12.86, Li2O 0.50, and H2Ocalc 12.31, total 97.37wt%. The resulting empirical formula, calculated on the basis of 96 anhydrous oxygen atoms, is (Ba7.54K0.32Na0.14)(Sigma 8.00)(Ba3.04Li1.57 square(1.39))(Sigma 6.00)Be-24.08(P23.88Al0.38Si0.03)(Sigma 24.29)O-96 center dot 32H(2)O. The single-crystal unit-cell parameters are a = 13.5398(2) angstrom and V = 2482.21(7) angstrom(3), space group I23. The eight strongest lines in the powder X-ray diffraction pattern [d(in angstrom)(I)(hkl)] are: 6.90(60)(200), 5.54(80)(211), 3.630(60)(321, 312), 3.212(70) (330, 411), 3.043(100)(420, 402), 2.885(70)(332), 2.774(80)(422), and 2.398(60)(440). The crystal structure of wilancookite has been refined, based on single-crystal X-ray diffraction data, to R-1 = 4.58%; the beryllophosphate framework is similar to that occurring in pahasapaite, and is based on zeolite-RHO cages. The mineral species and name were approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-034).

This work is focused on the crystal-chemical characterization of the cationic and anionic components of sodalite-group minerals (SGM) occurring in various igneous-to-metamorphic rocks and ejecta from the alkaline-potassic Somma-Vesuvius volcano (southern Italy). A combination of different analytical methods, i.e. , XRD, SEM, EPMA, SIMS, FTIR, and μ-FTIR-FPA imaging, have been used. Minor and trace volatile elements (H, C, and F) have been quantified for the first time (to the authors’ knowledge) by SIMS, and in situ ion probe data were integrated with information derived from FTIR spectroscopy. The studied samples correspond to sodalite sensu stricto , nosean and hauyne. SIMS measurements for H, F, and C (quantified as H2O, F, and CO2 wt.%, respectively) show contents 0.02–5.0 wt.% H2O, 0.01–0.14 wt.% F, and 0.08–2.95 wt.% CO2. Within the single crystals, the F and, to a lesser extent, CO2 concentrations are homogeneous, whereas, in terms of H2O, they span from relatively homogenous to strongly zoned. Single-crystal FTIR spectra of SGM can be grouped into sodalites and noseans/hauynes, according to the occurrence of the 12CO2 absorption at 2340 cm–1. The absorption due to H2O and/or OH groups occurs as a very broad band extending from 3700 cm–1 to 3000 cm–1. In all samples FTIR data show the presence of CO32–. The collected data allow us to fully characterize SGM from Somma-Vesuvius, providing also some constraints regarding their genesis. Present data can contribute to a more detailed understanding of the crystal chemistry of SGM, their geological environments of formation, and possibly of technological characteristics of their synthetic analogues.

We studied a partially serpentinized peridotite xenolith, found in the diatreme tuff-breccia deposit at Valle Guffari (Hyblean Plateau, southeastern Sicily, Italy), which is representative of the Hyblean peridotite xenolith suite. We also considered all published (21) whole-rock analyses of Hyblean peridotites, to investigate the metasomatizing effects of seawater-related hydrothermal fluids in the Hyblean basement, an in-situ remnant of the ultraslow-spreading Permian Tethys. In detail, we analyzed the serpentine veins by different techniques (scanning electron microscopy-SEM, electron-probe microanalysis-EPMA, micro-Raman spectroscopy, X-ray powder diffraction-XRPD) to determine the crystal-chemical composition and the structure of the veins. In addition, secondary ion mass spectrometry (SIMS) was applied to measure the abundance of trace elements. Serpentine veins are made up of two Fe-rich polytypes, chrysotile 2Mc1 and lizardite 1T. The chondrite-normalized rare earth element compositions of both serpentine polytypes are lower than 1, except for a modest light rare earth element (LREE) enrichment, and also in some fluid-mobile elements (FME: B, Rb, Sr, U). Conversely, the whole-rock composition of the studied peridotite xenolith is enriched with LREE and other trace elements (B, Sr, P, Th, U, Pb), like most Hyblean peridotites. The REE and multi-element patterns of Hyblean peridotites are akin to those of hydrothermal sediments from the Mid-Atlantic Ridge and St. Demetrio hill (northern Hyblean Plateau), and abyssal peridotites (serpentinites) whose trace element abundance is generally ascribed to melt–rock interaction. The integrated interpretation of the data and the documentation of hydrothermal minerals [(Na,S)-rich apatite, carbonates] in serpentine veins indicate that serpentinization-related hydrothermal fluids do have a primary role in metasomatism (mainly for the abundance of LREE and high field strength elements—HFSE) of ancient (Permian Tethys) and modern abyssal peridotites.

The mid-ocean ridge (MOR)-type gabbroic sequences from the Internal Ligurian ophiolites include olivine-rich troctolite lenses up to tens of metres thick. For one of these lenses, a portion of metre-scale thickness characterized by skeletal to dendritic olivines (harrisites) was observed near the contact with host gabbros. Spinels from the olivine-rich troctolites locally include Ti-pargasite to kaersutite frequently associated with phlogopite to Na-phlogopite. Spinel-hosted amphibole displays rare earth element (REE) patterns characterized by a negative Eu anomaly, thereby recording a magmatic process associated with plagioclase segregation. The amphiboles show variable depletion of light REE (LREE) relative to middle REE (MREE), and heavy REE (HREE) that are weakly enriched to depleted with respect to MREE. Crystallization of the inclusion-bearing spinels is attributed to cooling of hybrid melts that originated by interaction between primitive melts and gabbro-related melts relatively rich in SiO 2 and incompatible elements. Clinopyroxene and amphibole from the harrisites show extensive variability for trace element compositions, albeit characterized by subparallel incompatible element patterns. This chemical variability was most probably acquired in response to rapid crystal growth related to undercooling of the harrisite parental melt. We propose that the melt undercooling was related to interaction of a primitive melt batch with a gabbroic crystal mush. Supplementary material : Details of the analytical technique are available at http://doi.org/10.6084/m9.figshare.c.3284312

In order to assess the stability of the primary triphylite + sarcopside assemblage, we performed hydrothermal experiments between 400 and 700 C-omicron (Ni/NiO oxygen fugacity buffer, P = 1 kbar), starting from the Li(Fe2.5-x2+Mnx2+)(PO4)(2) (x = 0.0, 0.5, 1.0) compositions, which represent the ideal compositions of triphylite + sarcopside assemblages in which both minerals occur in a 1: 1 molar ratio. The triphylite + sarcopside assemblage is observed in all experiments, associated with other phosphates like (Fe2+, Mn2+)(2)P2O7, (Fe2+, Mn2+) Fe-2(3+)(PO4)(2)(OH)(2) center dot nH(2)O, or Fe-4(3+)(Fe2+, Mn2+) (3)(PO4)(6). Electron-microprobe and SIMS analyses show a progressive decrease of the Li contents in the triphylites, balanced by an increase of their Fe2+-contents, when the temperature increases. These compositional changes are due to the increase of the triphylite-sarcopside miscibility along the Li-2(Fe2+, Mn2+)(2)(PO4)(2)-Fe2+(Fe2+, Mn2+)(2)(PO4)(2) solid solution; the experimental phase diagrams can consequently be used as a geothermometer to calculate the exsolution temperatures of the assemblages. A linear fit of the experimental data leads to the general equation: T(C-omicron) = (-142 * XFe) - (773 * Li pfu) + 1131, where XFe = Fe/(Fe + Mn). The uncertainty is around +/- 15 C-omicron, and the influence of pressure is assumed to be negligible. By using this equation, exsolution temperatures were calculated for nine triphylite-sarcopside assemblages from pegmatites; these temperatures do not represent the crystallization temperatures of the phosphate nodules, but correspond to the closing temperature of the triphylite-sarcopside element exchange. Nevertheless, these temperatures, between 276 and 397 C-omicron, are in fairly good agreement with those generally accepted for the crystallization of primary phosphate assemblages in granitic pegmatites.

A suite of Ti-bearing garnets from magmatic, carbonatitic, and metamorphic rocks was studied by electron probe microanalysis (EPMA), X-ray powder diffraction (XRPD), single-crystal X-ray diffraction (SCXRD), Mossbauer spectroscopy, and secondary ion mass spectrometry (SIMS) to better characterize their crystal chemistry. The studied garnets show TiO2 varying in the range of 4.9(1) to 17.1(2) wt% and variable Fe3+/EFe content. SIMS analyses allowed quantification of light elements yielding H2O in the range 0.091(7)-0.46(4), F in the range 0.004(1)-0.040(4), and Li2O in the range 0.0038(2)-0.014(2) wt%. Mossbauer analysis provided spectra with different complexity, which could be fitted to several components variable from one (YFe+) to four (YFe2+, zFe(2+), YFe3+, zFe(3+)). A good correlation was found between the Fe3+/EFe resulting from the Mossbauer analysis and that derived from the Flank method.X-ray powder analysis revealed that the studied samples are a mixture of different garnet phases with very close cubic unit-cell parameters as recently found by other authors. Single-crystal X-ray refinement using anisotropic displacement parameters were performed in the 'cad space group and converged to 1.65 RI < 2.09% and 2.35 < wR(2)< 3.02%. Unit-cell parameters vary in the range 12.0641(1) < a 12.1447(1) angstrom, reflecting different Ti contents and extent of substitutions at tetrahedral site.The main substitution mechanisms affecting the studied garnets are: yR(4+) zR3+ zsi YR3+ (schorlomite substitution); YR2+ + ZR(4+) 4-3 2YR(3+) (morimotoite substitution); YR3+ 4-> YFe3+ (andradite substitution); in the above substitutions yR(2+) = Fez+, mg(2+), mn(2+); Sigma R4+ = Ti; YR3+ = Fe3+, Al3+, Cr3+; Fe3+= Al3+. Minor substitutions, such as 2Y-Fp++ Sigma Fe2+ 44 2YFe(3+) + zSi, (SiO4)(4-) <-> (04H4)4-, F-4-> OH-, and Y12.4 + xR(+)(4)-> YR3+ + xCa(2+), with YR.4+ = Ti, Zr; YR3+ = Fe3+, Al, Cr3+; xR+= Na, Li also occur.

Mantle xenoliths collected from Fuerteventura, one of the easternmost Canary Islands, exhibit a complex evolutionary history comprising events of depletion, serpentinization, dehydration and melt metasomatism. Each of these events left imprints on both the texture and chemistry of the xenoliths. Extensive partial melting is shown by complete lack of primary clinopyroxene, the ultra-refractory trac...

We present a geochemical study on olivine and clinopyroxene‐hosted melt inclusions (MIs) from 2001 to 2006 Etna basaltic lavas and pyroclastites. Three MI suites are distinguished on the basis of trace element fingerprinting. Type‐1 MIs (from 2001 Upper South and 2002 Northeast vents) share their trace element signature with low‐K lavas erupted before 1971. Critical trace element ratios (e.g., K/La, Ba/Nb), along with Pb isotope data of Type‐1 MIs provide evidence for a heterogeneous mantle source resulting from mixing of three end‐members with geochemical and isotopic characteristics of EM2, DMM, and HIMU components. Type‐1 MIs composition does not support involvement of subduction‐related components. Type‐2 (from 2001 Lower and 2002 South vents) and Type‐3 (2004 eruption) MIs reveal “ghost plagioclase signatures,” namely lower concentrations in strongly incompatible elements, and positive Sr, Ba, and Eu anomalies. Both Type‐1 and Type‐2 MIs occur in 2006 olivines, which highlight the occurrence of mixing between Type‐1 and Type‐2 end‐members. Type‐2/Type‐3 MIs testify to en route processes (plagioclase assimilation and volatile fluxing) peculiar for “deep dike fed” eruptions. The latter are strongly controlled by tectonics or flank instability that occasionally promote upraise of undegassed, more radiogenic primitive magma, which may interact with plagioclase‐rich crystal mush/cumulates before erupting. Type‐2/Type‐3 MIs approach the less radiogenic Pb isotopic composition of plagioclase from prehistoric lavas, thus suggesting geochemical overprinting of present‐day melts by older products released from distinct mantle sources. Our study emphasizes that MIs microanalysis offers new insights on both source characteristics and en route processes, allowing to a link between melt composition and magma dynamics.

The 'Y-3' tephra is a crucial stratigraphic marker within the central Mediterranean region that falls close to the Marine Isotope Stage 3/2 transition and a cooling event proposed as a correlative of the North Atlantic Heinrich Stadial 3 (HS3). Consequently, this tephra offers great potential to assess any leads and lags in environmental responses to this abrupt climatic transition. New grain-specific glass analysis (EMPA and LA-ICP-MS) of the type locality Y-3 tephra recorded in the Ionian Sea confirms its origin from Campi Flegrei (CF) but reveals that it is compositionally different from the previously suggested proximal equivalent the VRa eruptive unit (Verdolino Valley, CF). Consequently, the Ar-40/Ar-39 age of the VRa should not be exported distally to the Y-3 tephra. Instead, we propose a new robust age for the Y-3 tephra following its identification in the Tenaghi Philippon sedimentary record, NE Greece. A Bayesian-based C-14 age model from Tenaghi Philippon provides a distal age of 28,680-29,420 cal yrs BP for the Y-3 tephra. The identification of this tephra in NE Greece markedly extends its known eastern dispersal. Whilst its stratigraphic position falls within the latter part of a period of low tree pollen percentages related to dry stadial conditions. This new age and environmental context suggest that this marker postdates the onset of HS3 in the eastern Mediterranean region by similar to 2300 years. (C) 2014 Elsevier Ltd. All rights reserved.

Tephra layers preserved in marine sediments can contribute to the reconstruction of volcanic histories and potentially act as stratigraphic isochrons to link together environmental records. Recent developments in the detection of volcanic ash (tephra) at levels where none is macroscopically visible (so-called 'crypto-tephra') have greatly enhanced the potential of tephrostratigraphy for synchronising environmental and archaeological records by expanding the areas over which tephras are found. In this paper, crypto-tephra extraction techniques allow the recovery of 8 non-visible tephra layers to add to the 9 visible layers in a marine sediment core (LC21),from the SE Aegean Sea to form the longest, single core record of volcanic activity in the Aegean Sea. Using a novel, shard-specific methodology, sources of the tephra shards are identified on the basis of their major and trace element single-shard geochemistry, by comparison with geochemical data from proximal Mediterranean volcanic stratigraphies. The results indicate that the tephra layers are derived from 14 or 15 separate eruptions in the last ca 161 ka BP: 9 from Santorini; 2 or 3 from Kos, Yali, or Nisyros; 2 from the Campanian province; and one from Pantelleria. The attributions of these tephra layers indicate that 1) inter-Plinian eruptions from Santorini may have produced regionally significant tephra deposits, 2) marine tephrostratigraphies can provide unique and invaluable data to eruptive histories for island volcanoes, and 3) tephra from both Pantelleria and Campania may be used to correlate marine records from the Aegean Sea to those from the Tyrrhenian, Adriatic and Ionian Seas. (C) 2015 Elsevier Ltd. All rights reserved.

Sites in North Africa hold key information for dating the presence of Homo sapiens and the distribution of Middle Stone Age (MSA), Middle Palaeolithic (MP) and Later Stone Age (LSA) cultural activity in the Late Pleistocene. Here we present new and review recently published tephrochronological evidence for five cave sites in North Africa with long MSA/MP and LSA cultural sequences. Four tephra horizons have been identified at the Haua Fteah (Cyrenaica, Libya). They include cryptotephra evidence for the Campanian Ignimbrite (CI) eruption dating to similar to 39 ka that allows correlation with other Palaeolithic sequences in the eastern Mediterranean and as far north as Russia. Cryptotephra have also been recorded from the Moroccan sites of Taforalt, Rhafas and Dar es-Soltane 1. At Taforalt the geochemical composition suggests a provenance in the Azores, while examples from Sodmein (Egypt) appear to derive from central Anatolia and another unknown source. In these latter examples chemical compositional data from relevant proximal volcanic centres is currently lacking so the identification of tephra in layers of known age and cultural association provides the first reliable age determinations for distal volcanic events and their geographical extent. The future potential for tephrochronological research in North Africa is also discussed. (C) 2014 Published by Elsevier Ltd.