Search results for " petrology"

Experimental investigation on peralkaline silicic magmas of Pantelleria Island: inferences on pre-eruptive conditions, magma evolution and water solu…

2017

Halloysite nanotubes with fluorinated cavity: an innovative consolidant for paper treatment

2016

AbstractHybrid material based on halloysite nanotubes (HNTs) and sodium perfluorooctanoate (NaPF8) was used as a consolidant for paper treatment. The consolidation efficiency was determined by thermogravimetry as well as by paper grammage determination. Morphological analysis of the treated paper was performed by means of scanning electron microscopy while the effect of modified HNTs on the thermal behaviour of the cellulose fibres was investigated by differential scanning calorimetry which determined the combustion enthalpy of the paper.Water contact angle measurements were performed to study the paper wettability. The physico-chemical properties investigated (mesoscopic structure, thermal…

Partial melting of metagreywacke: a calculated mineral equilibria study

2008

Greywacke occurs in most regionally metamorphosed orogenic terranes, with depositional ages from Archean to recent. It is commonly the dominant siliciclastic rock type, many times more abundant than pelite. Using calculated pseudosections in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O system, the partial melting of metagreywacke is investigated using several natural protolith compositions that reflect the main observed compositional variations. At conditions appropriate for regional metamorphism at mid-crustal depths (6–8 kbar), high-T subsolidus assemblages are dominated by quartz, plagioclase and biotite with minor garnet, orthoamphibole, sillimanite, muscovite and/or K-feldspar (±Fe–T…

Migmatites in the Ivrea Zone (NW Italy): Constraints on partial melting and melt loss in metasedimentary rocks from Val Strona di Omegna

2013

Abstract The mid to lower crustal metamorphic field gradient through amphibolite and granulite facies rocks in the Ivrea Zone offers the potential to study partial melting and melt loss in the crust. Metapelitic rocks in Val Strona di Omegna show a progressive evolution in migmatite structures from metatexites with rare isolated leucosome veins in the amphibolite facies rocks to stromatic migmatites and diatexites in granulite facies rocks. Little field or petrographic evidence for melting can be seen on crossing the position of the modelled wet solidus, consistent with the small amounts of melt predicted to occur by H2O-saturated melting. The first field evidence for partial melting, in th…

Influence of temperature and background electrolyte on the sorption of neptunium(V) on Opalinus Clay

2012

Abstract The temperature dependence of the sorption of 8 μM neptunium(V) on Opalinus Clay (OPA, Mont Terri, Switzerland) was investigated between 40 and 80 °C and compared to previous results for 20 °C. The batch experiments were performed under ambient air conditions in synthetic pore water (pH = 7.6, I = 0.4 M) under variation of the solid-to-liquid ratio between 2 and 20 g/L. Under these conditions the sorption of Np(V) on OPA was found to be an endothermic process as the average distribution coefficient (K d ) increases continuously with increasing temperature from 23 ± 4 L/kg at 40 °C to 678 ± 254 L/kg at 80 °C. In the temperature range of 40-80 °C, the plot of log(K d ) vs. 1/T could …

Trace-element partitioning and boron isotope fractionation between white mica and tourmaline

2011

High-grade metamorphic tourmaline and white mica from the Broken Hill area, NSW, Australia, were analyzed with laser-ablation ICP–MS and ion-probe techniques to investigate the partitioning of trace elements and fractionation of boron isotopes between these two coexisting phases. The results indicate that most trace elements show partition coefficients close to one; only elements such as Zn, Sr, the light rare-earth elements La and Ce, and Th, partition preferentially into tourmaline, whereas Rb, Ba, W, Sn, and Nb and Ta are preferentially partitioned into coexisting mica. The ion-probe measurements demonstrate that boron isotopes are strongly fractionated between mica and tourmaline, with …

Historical mining and smelting in the Vosges Mountains (France) recorded in two ombrotrophic peat bogs

2010

Two peat sequences were sampled in the vicinity of the main mining districts of the Vosges Mountains: Sainte-Marie-aux-Mines and Plancher-les-Mines. Lead isotopic compositions and excess lead fluxes were calculated for each of these radiocarbon-dated sequences. Geochemical records are in very good agreement with the mining history of the area, well known over the last millennium. Except for an anomaly corresponding to the Middle Bronze Age which has not yet been resolved, there is no clear geochemical evidence of local metal production in the Vosges before the 10th century as excess lead deposition archived between 500 BC and 500 AD is attributed to long-range transport of polluted particul…

Occurrence and recovery potential of rare earth elements in Finnish peat and biomass combustion fly ash

2019

Rare earth elements (REEs) are highly important in the modern society as a result of their wide use in various fields of industry. Their high supply risk and increase in demand has led to classification as critical materials, and consequently, new resources for REEs are being prospected widely. Coal fly ash has been suggested as a possible secondary resource for REEs, but very little information is available regarding REE occurrence in biomass or peat derived fly ash. In this paper, fly ash samples from commercial power plants using peat and biomass as fuel were studied for REEs. The average concentration of REEs was 530 ppm, with up to 920 ppm in one fly ash. Five out of seven fly ashes we…

Chemical weathering of volcanic rocks at the island of Pantelleria, Italy: Information from soil profile and soil solution investigations

2007

Abstract Concentrations of major, minor and trace elements were determined in soil profiles and soil solutions from the island of Pantelleria, Sicily Channel, to evaluate the weathering extent of soils evolved on trachytic and pantelleritic rocks and the aqueous transport of elements by their soil solutions. The chemical index of alteration (CIA) indicates a low-to-moderate degree of weathering; consistently, the mineralogical and geochemical imprints of the parent rocks are generally preserved. The chemical weathering appears to be incongruent, owing to primary minerals and glass dissolving to a variable degree while secondary minerals have formed. Based on the calculated saturation state …

Changes in fish mercury concentrations over 20 years in an acidified lake subject to experimental liming

2007

Abstract Lake Iso Valkjarvi (southern Finland, Europe) was divided in two with a plastic curtain in 1991. One half was neutralized with CaCO 3 , and the other acted as a control. Mercury concentrations of perch ( Perca fluviatilis ) and northern pike ( Esox lucius ) in the limed and control side of the lake were studied both before and after the treatment. Average Hg concentrations of perch and pike were 0.40 and 1.2 μg g −1 (ww) in the early 1980s and 0.25 and 0.72 μg g −1 (ww) a decade later at the time of liming. Ten years after the liming the Hg concentrations of perch in the limed and control sides of the lake were 0.21 and 0.28 μg g −1 (ww) and those of pike were 0.69 and 0.43 μg g −1…