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An enigmatic record of light lithophile element (LLE) zoning in pyroxenes in basaltic shergottite meteorites, whereby LLE concentrations decrease dramatically from the cores to the rims, has been interpreted as being due to partitioning of LLE into a hydrous vapor during magma ascent to the surface on Mars. These trends are used as evidence that Martian basaltic melts are water-rich (McSween et al., 2001). Lithium and boron are light lithophile elements (LLE) that partition into volcanic minerals and into vapor from silicate melts, making them potential tracers of degassing processes during magma ascent to the surface of Earth and of other planets. While LLE degassing behavior is relatively well understood for silica-rich melts, where water and LLE concentrations are relatively high, very little data exists for LLE abundance, heterogeneity and degassing in basaltic melts. The lack of data hampers interpretation of the trends in the shergottite meteorites. Through a geochemical study of LLE, volatile and trace elements in olivine-hosted melt inclusions from Kilauea Volcano, Hawaii, it can be demonstrated that lithium behaves similarly to the light to middle rare Earth elements during melting, magma mixing and fractionation. Considerable heterogeneity in lithium and boron is inherited from mantle-derived primary melts, which is dominant over the fractionation and degassing signal. Lithium and boron are only very weakly volatile in basaltic melt erupted from Kilauea Volcano, with vapor-melt partition coefficients 4 wt%. The observed terrestrial LLE partitioning behavior is extrapolated to Martian primitive melts through modeling. The zoning observed in the shergottite pyroxenes is only consistent with degassing of LLE from a Martian melt near its liquidus temperature if the vapor-melt partition coefficient was an order of magnitude larger than observed on Earth. The range in LLE and trace elements observed in shergottite pyroxenes are instead consistent with concurrent mixing and fractionation of heterogeneous melts from the mantle.

Magma mixing and crystal mush disaggregation are important processes in basaltic magma reservoirs. We carried out a detailed petrological and geochemical study on a highly plagioclase-phyric eruption within the Eastern Volcanic Zone of Iceland—the Skuggafjöll eruption—to investigate crystal storage and transport processes within a single magmatic system. Crystal content and phase proportions vary between samples: the least phyric samples have phase proportions similar to the low-pressure, three-phase gabbro eutectic (plg:cpx:ol \~ 11:6:3), whereas highly phyric samples are strongly enriched in plagioclase (plg:cpx:ol \~ 8:1:1). Statistically significant geochemical variability in 28 whole-rock samples collected across the eruption can be accounted for by variable accumulation of a troctolitic assemblage containing plagioclase and olivine in an approximately 9:1 ratio. Two macrocryst assemblages are defined using compositional and textural information recorded in QEMSCAN® images: a primitive assemblage of high-anorthite plagioclase (An\textgreater83) and high-forsterite olivine (Fo\textgreater84), and an evolved assemblage of low-anorthite plagioclase (An\textless79), low-forsterite olivine (Fo\textless82) and clinopyroxene (Mg# \~ 82). Plagioclase and olivine have strongly bimodal composition distributions whereas the composition distribution of clinopyroxene is unimodal. The mean trace element composition of melt inclusions hosted within high-forsterite olivine and high-anorthite plagioclase macrocrysts is the same (mean Ce/Y \~ 0·47–0·48), confirming that both primitive macrocryst phases crystallized from the same distribution of melts. Clinopyroxene macrocrysts and matrix glasses are in Ce/Yb equilibrium with each other, indicating that the evolved assemblage crystallized from melts with a more incompatible trace element-enriched composition (mean Ce/Y \~ 0·65–71) than the primitive assemblage. Variability in whole-rock, macrocryst and melt inclusion compositions suggests that the Skuggafjöll magma experienced two stages of crystallization. Primitive macrocrysts crystallized first from incompatible trace element-depleted melts within a shallow crustal magma reservoir. These primitive macrocrysts were subsequently stored in crystal mushes that ultimately disaggregated into an evolved and incompatible trace element-enriched magma from which the evolved assemblage crystallized. On average, \~17% of the erupted magma at Skuggafjöll is composed of accumulated macrocrysts entrained from crystal mushes. The timescale between mush disaggregation and eruption, during which crystal accumulation occurred, was short—of the order of years—according to simple diffusion calculations. Striking petrological similarities between Skuggafjöll and other highly phyric eruptions both in Iceland and along mid-ocean ridges indicate that crystal accumulation by mush disaggregation is likely to be an important mechanism for generating highly phyric magmas in basaltic plumbing sy

We present the results of a study of volcanic gases at Soufrière Hills Volcano, Montserrat, which includes the first spectroscopic measurements of the major gas species CO2 and H2S at this volcano using a Multisensor Gas Analyzer System (MultiGAS) sensor. The fluxes of CO2 and H2S were 640–2750 t/d and 84–266 t/d, respectively, during July 2008, during a prolonged eruptive pause. The flux of CO2 is similar to estimates for the entire arc from previous geochemical studies, while the measured H2S flux significantly alters our interpretation of the sulphur budget for this volcano. The fluxes of both sulphur and carbon show considerable excesses over that which can be supplied by degassing of erupted magma. We demonstrate, using thermodynamic models and published constraints on preeruptive volatile concentrations, that the gas composition and fluxes are best modeled by mixing between (1) gases derived from isobaric quenching of mafic magma against cooler andesite magma at depth and (2) gases derived from shallower rhyolitic interstitial melt within the porpyritic andesite. The escape of deep‐derived gases requires pervasive permeability or vapor advection extending to several kilometers depth in the conduit and magma storage system. These results provide more compelling evidence for both the contribution of unerupted mafic magma to the volatile budget of this andesitic arc volcano and the importance of the intruding mafic magma in sustaining the eruption. From a broader perspective, this study illustrates the importance and role of underplating mafic magmas in arc settings. These magmas play an important role in triggering and sustaining eruptions and contribute in a highly significant way to the volatile budget of arc volcanoes.

Lavas from the current eruption of the Soufrière Hills Volcano, Montserrat exhibit evidence for magma mingling, related to the intrusion of mafic magma at depth. We present detailed field, petrological, textural and geochemical descriptions of mafic enclaves in andesite erupted during 2009-2010, and subdivide the enclaves into three distinct types. Type A are mafic, glassy with chilled margins and few inherited phenocrysts. Type B are more evolved with high inherited phenocryst contents and little glass, and are interpreted as significantly hybridised. Type C are composite, with a mafic interior (type A) and a hybrid exterior (type B). All enclaves define tight linear compositional trends, interpreted as mixing between a mafic end-member (type A) and host andesite. Enclave glasses are rhyolitic, owing to extensive crystallisation during quenching. Type A quench crystallisation is driven by rapid thermal equilibration during injection into the andesite. Conversely, type B enclaves form in a hybridised melt layer, which ponded near the base of the chamber and cooled more slowly. Vesiculation near the mafic-silicic interface resulted in disruption of the hybridised layer and the formation of the Type B enclaves. The composite enclaves represent an interface between types A and B, suggesting multiple episodes of mafic injection.

Major elements, trace elements and volatiles were measured in 110 olivine-hosted melt inclusions from the subglacial Skuggafjöll eruption in the Eastern Volcanic Zone of Iceland. Variations in melt inclusion trace element concentrations can be accounted for by incomplete mixing of diverse mantle parental melts accompanied by variable extents of fractional crystallisation. Binary mixing between an incompatible trace element-enriched and depleted melts provides a good fit to observed variations in trace element ratios such as Ce/Y. Surprisingly, the CO2 contents of melt inclusions correlate negatively with their degree of trace element enrichment. Depleted, low-Ce/Y inclusions with ∼1200 ppm CO2 have high CO2/Nb contents (∼400), suggesting that melts experienced little or no CO2 exsolution before inclusion entrapment. Enriched, high-Ce/Y inclusions contain ∼300 ppm CO2, have low CO2/Nb (contents 50–100) and melts are likely to have exsolved much of their original CO2 contents prior to inclusion entrapment. The negative correlation between CO2 content and trace element enrichment may arise either from the more efficient exsolution of CO2 from enriched melts, or from the intrusion of CO2-supersaturated depleted melts into enriched melts that had already exsolved much of their original CO2 contents. Some inclusions have lower CO2 contents than predicted from binary mixing models, which suggests that at least some CO2 exsolution occurred concurrently with mixing. Enriched inclusions record entrapment pressures of ∼0.5 kbar. These pressures probably correspond to the depth of mixing. Higher pressures recorded in depleted inclusions may have resulted from the development of CO2 supersaturation during ascent from storage at ≥1.5 kbar. The presence of CO2 supersaturation in melt inclusions has the potential to constrain timescales of melt inclusion entrapment.

Satellite-measured SO2 mass loadings and ground-based measurements of SO2 emission rate are not directly comparable, with ∼40% differences between mean emissions reported by each technique from Tungurahua volcano, Ecuador, during late 2007. Numerical simulations of postemission processing and dispersal of Tungurahua’s SO2 emissions enable more effective comparison of ground- and satellite-based SO2 data sets, reducing the difference between them and constraining the impact of plume processing on satellite SO2 observations. Ground-based measurements of SO2 emission rate are used as the model input, and simulated SO2 mass loadings are compared to those measured by the Ozone Monitoring Instrument (OMI). The changing extent of SO2 processing has a significant impact on daily variation in SO2 mass loading for a fixed volcanic emission rate. However, variations in emission rate at Tungurahua are large, suggesting that overall volcanic source strength and not subsequent processing is more likely to be the dominant control on atmospheric mass loading. SO2 emission rate estimates are derived directly from the OMI observations using modeled SO2 lifetime. Good agreement is achieved between both observed and simulated mass loadings (∼21%) and satellite-derived and ground-measured SO2 emission rates (∼18%), with a factor of 2 improvement over the differences found by simple direct comparison. While the balance of emission source strength and postemission processing will differ between volcanoes and regions, under good observation conditions and where SO2 lifetime is ∼24 hours, satellite-based sensors like OMI may provide daily observations of SO2 mass loading which are a good proxy for volcanic source strength.

The 1959 Kīlauea Iki eruption provides a unique opportunity to investigate the process of shallow magma mixing, its impact on the magmatic volatile budget and its role in triggering and driving episodes of Hawaiian fountaining. Melt inclusions hosted by olivine record a continuous decrease in H2O concentration through the 17 episodes of the eruption, while CO2 concentrations correlate with the degree of post-entrapment crystallization of olivine on the inclusion walls. Geochemical data, when combined with the magma budget and with contemporaneous eruption observations, show complex mixing between episodes involving hot, geochemically heterogeneous melts from depth, likely carrying exsolved vapour, and melts which had erupted at the surface, degassed and drained-back into the vent. The drained-back melts acted as a coolant, inducing rapid cooling of the more primitive melts and their olivines at shallow depths and inducing crystallization and vesiculation and triggering renewed fountaining. A consequence of the mixing is that the melts became vapor-undersaturated, so equilibration pressures cannot be inferred from them using saturation models. After the melt inclusions were trapped, continued growth of vapor bubbles, caused by enhanced post-entrapment crystallization, sequestered a large fraction of CO2 from the melt within the inclusions. This study, while cautioning against accepting melt inclusion CO2 concentrations “as measured” in mixed magmas, also illustrates that careful analysis and interpretation of post-entrapment modifications can turn this apparent challenge into a way to yield novel useful insights into the geochemical controls on eruption intensity.

Bovine respiratory disease (BRD) is the leading cause of morbidity and death in feedlot cattle. Prognostic tools for the prediction of morbidity and severity of BRD are currently lacking. Blood L-lactate (LAC) is a metabolite that increases because of various conditions including stress and cellular hypoxia, which frequently accompany severe forms of BRD. Results of another study conducted in feedlot cattle indicate that low LAC concentration at processing was associated with a greater risk of developing BRD during the early feeding period. Investigators of other studies in double-muscled calves and in hospital settings have demonstrated that a single measurement LAC can be predictive of death. The objectives of this study were to assess the clinical usefullness of evaluation of LAC concentration at processing as a predictor of BRD during the early feeding period and to assess serial measurement of LAC concentration in feedlot steers with BRD., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2013

We demonstrate that the intrinsic electron doping of monolayer epitaxial graphene on SiC(0001) can be tuned in a controlled fashion to holes via molecular doping with the fluorinated fullerene C60F48. In situ angle-resolved photoemission is used to measure an upward shift of (0.6 ± 0.05) eV in the Dirac point from −0.43 eV to +0.17 eV relative to the Fermi level. The carrier density is observed to change from n ∼ (1 × 1013 ± 0.1 × 1013) cm−2 to p ∼ (2 × 1012 ± 1 × 1012) cm−2. We introduce a doping model employing Fermi-Dirac statistics which explicitly takes temperature and the highly correlated nature of molecular orbitals into account. The model describes the observed doping behaviour in our experiment and readily explains why net p-type doping was not achieved in a previous study [Coletti et al., Phys. Rev. B 81, 8 (2010)] which used tetrafluorotetra-cyanoquinodimethane (F4-TCNQ).

Between January 2011 and April 2012, Santorini volcano (Greece) experienced a period of unrest characterised by the onset of detectable seismicity and caldera-wide uplift. This episode of inflation represented the first sizeable intrusion of magma beneath Santorini in the past 50 years. We employ a new approach using 222Rn-δ13C systematics to identify and quantify the source of diffuse degassing at Santorini during the period of renewed activity. Soil CO2 flux measurements were made across a network of sites on Nea Kameni between September 2010 and January 2012. Gas samples were collected in April and September 2011 for isotopic analysis of CO2 (δ13C), and radon detectors were deployed during September 2011 to measure (222Rn). Our results reveal a change in the pattern of degassing from the summit of the volcano (Nea Kameni) and suggest an increase in diffuse CO2 emissions between September 2010 and January 2012. High-CO2-flux soil gas samples have δ13C ~ 0‰. Using this value and other evidence from the literature we conclude that these CO2 emissions from Santorini were a mixture between CO2 sourced from magma, and CO2 released by the thermal or metamorphic breakdown of crustal limestone. We suggest that this mixing of magmatic and crustal carbonate sources may account more broadly for the typical range of δ13C values of CO2 (from ~ - 4‰ to ~ + 1‰) in diffuse volcanic and fumarole gas emissions around the Mediterranean, without the need to invoke unusual mantle source compositions. At Santorini a mixing model involving magmatic CO2 (with δ13C of -3 ± 2‰ and elevated (222Rn)/CO2 ratios ~105-106 Bqkg -1) and CO2 released from decarbonation of crustal limestone (with (222Rn)/CO2 ~ 30-300 Bqkg-1, and δ13C of +5‰) can account for the δ13C and (222Rn)/CO2 characteristics of the 'high flux' gas source. This model suggests ~60% of the carbon in the high flux deep CO2 end member is of magmatic origin. This combination of δ13C and (222Rn) measurements has potential to quantify magmatic and crustal contributions to the diffuse outgassing of CO2 in volcanic areas, especially those where breakdown of crustal limestone is likely to contribute significantly to the CO2 flux. © 2013 Elsevier B.V.

Surface conductivity and C1s core level measurements were employed to show that surface transfer doping of hydrogen-terminated diamond C(100) can be achieved with a molecular heterojunction formed with C60F48 and an intralayer of zinc-tetraphenylporphyrin. Measurement of the shift in the diamond Fermi energy shows that the zinc-tetraphenylporphyrin (ZnTPP) layer modifies the C60F48–diamond interaction, modulating the extent of charge transfer between the diamond and the fluorofullerene. In contrast to the case of C60F48 acceptors, the presence of a ZnTPP layer prevents the formation of air-induced surface conductivity, showing that the intralayer acts to selectively separate these two doping channels.

We report the first satellite-based survey of volcanic sulphur dioxide (SO 2) degassing in Papua New Guinea, using Ozone Monitoring Instrument (OMI) data. OMI is sensitive to low-level passive degassing. These observations are useful for volcano monitoring, hazard assessment (particularly aviation hazard) and assessment of arc geochemical budgets and are of immense value in remote regions with little ground-based instrumentation, such as Papua New Guinea. We identify Bagana, Manam, Rabaul, Ulawun and Langila as the active sources of volcanic SO 2 in Papua New Guinea, with Bagana being the largest source. We present an OMI SO 2 time series for 2005-2008 and a total detected regional output of ∼1.8 × 10 9 kg SO 2. About 40% of emissions were released by major eruption events at Manam (January 2005), Bagana (June 2006) and Rabaul (October 2006). Over the past century however, we estimate that major explosive eruptions contribute

Volcanic gas emissions illustrate a complex volatile budget for Soufrière Hills Volcano, Montserrat. Fluxes of sulphur dioxide, carbon dioxide, hydrogen sulphide and hydrogen chloride (and probably water) are substantial from this arc volcano. Additional sources of volatiles in addition to the erupting andesite are required to satisfy the mass balance defined by gas emissions and petrological constraints. Mafic magma is intruded at depths of >10 km, supplying volatiles by quenching, crystallising and vesiculating at the andesite-mafic magma interface. Sulphur, carbon dioxide and other volatiles supplied to the system migrate to the surface and their fluxes remain high while mafic recharge at depth is sustained. Decompression degassing of porphyritic andesite supplies chlorine and water to the gas plume. Chlorine partitions into vapour from the melt during periods of active extrusion, making the HCl/SO 2 ratio of volcanic gases a reliable indicator of the onset of eruptive activity. Studies of this volatile budget highlight the role of deep degassing and vapour production at arc volcanoes, which are important mechanisms for driving the eruption due to its effects on magma buoyancy and the advection of heat through the system. Copyright © 2010 by the American Geophysical Union.

Arc volcanoes commonly show evidence of mixing between mafic and silicic magma. Melt inclusions and matrix glasses in andesite erupted from Soufrière Hills Volcano, Montserrat, include an anomalously K 2O-rich population which shows close compositional overlap with residual glass from mafic inclusions. We suggest that these glasses represent the effects of physical mixing with mafic magma, both during ascent and by diffusive exchange during the formation of mafic inclusions. Many glasses are enriched only in K2O, suggesting diffusive contamination by high-K mafic inclusion glass; others are also enriched in TiO2, suggesting physical mixing of remnant glass. Some mafic inclusion glasses have lost K 2O. The preservation of this K-rich melt component in the andesite suggests short timescales between mixing and ascent. Diffusive timescales are consistent with independent petrological estimates of magma ascent time.

International audience; Aims Thiazolidinediones (TZDs) are associated with a higher risk of bone fracture in women compared with men. The aim of the present study was to investigate whether TZDs could influence osteocyte behaviour and contribute to the skeletal phenotype observed in TZD-treated patients.Methods The murine MLO-Y4 cell line was used as a source of osteocytes. These cells were cultured for 24h with 0, 10−8m, 10−7m, 10−6m, 10−5m or 10−4m of pioglitazone, rosiglitazone or troglitazone in the presence or absence of 17β-oestradiol. The extent of osteocyte apoptosis was assessed, as was the expression of the bone formation inhibitor sclerostin and receptor activator for nuclear factor κB ligand (RANKL) also.Results In the absence of 17β-oestradiol, pioglitazone, rosiglitazone and troglitazone induced osteocyte apoptosis dose-dependently even at the lowest concentration of 10−8m. Furthermore, the expression of sclerostin but not RANKL was significantly increased in TZD-treated cultures compared with untreated cultures. The presence of 17β-oestradiol significantly reduced TZD-induced osteocyte apoptosis and also sclerostin up-regulation.Conclusions These findings therefore raise the potential concern of using TZDs in post-menopausal women where the lack of oestrogen would not prevent osteocyte apoptosis and sclerostin up-regulation and may aggravate the reduction in bone mass in these patients.

International audience; Charcot neuro-osteoarthropathy (CNO) is a devastating condition affecting most commonly the foot/ankle joint in diabetic patients and may lead to severe deformities and amputation. Peripheral sensory neuropathy seems to be a pre-requisite to the development of CNO . The aim of this review article is to summarise the skeletal effects of the nervous system on bone remodelling and fracture healing of normal and damaged joints and to describe how neuropathy, in the context of modern concept of neuro-osteopathology, is crucial in the predisposition of the patient to develop acute CNO .