Search results for "MELT"
showing 10 items of 435 documents
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…
Diet and prey size spectrum of pikeperch in lakes in central Finland
2004
The stomach content of pikeperch Sander lucioperca was studied in 24 lakes in central Finland. The most important prey species was smelt Osmerus eperlanus then perch Perca fluviatilis. The proportion of cyprinids as prey increased with pikeperch total length (LT) and lake phosphorus content. Prey L T and pikeperch L T correlated positively, but the prey-to-predator size ratio correlated negatively with pikeperch L T .
Gastric evacuation rate of burbot fed single-fish meals at different temperatures
1997
The gastric evacuation rates of burbot Lota lota, fed a single meal of vendace, Coregonus albula, were measured in the laboratory at five temperatures (1·3, 2·6, 4·8, 9·4 and 12·6° C). Gastric evacuation rate increased exponentially with increasing temperatrure, but the results suggest that gastric evacuation rates of burbot at low temperatures are lower than those of other freshwater fish species. Temperature and the ratio of meal weight to burbot weight were the most important factors affecting gastric evacuation rate. There was no significant difference in gastric evacuation rate between three different prey species: vendace, perch Perca fluviatilis, and smelt Osmerus eperlanus.
Tertiary Ultrapotassic Volcanism in Serbia: Constraints on Petrogenesis and Mantle Source Characteristics
2005
The Serbian province of Tertiary ultrapotassic volcanism is related to a post-collisional tectonic regime that followed the closure of the Tethyan Vardar Ocean by Late Cretaceous subduction beneath the southern European continental margin. Rocks of this province form two ultrapotassic groups; one with affinities to lamproites, which is concentrated mostly in the central parts of the Vardar ophiolitic suture zone, and the other with affinities to kamafugites, which crops out in volcanoes restricted to the western part of Serbia. The lamproitic group is characterized by a wide range of Sr/Sri (0 70735–0 71299) and Nd/Ndi (0 51251–0 51216), whereas the kamafugitic group is isotopically more ho…
Origin and crystallization history of Permian tholeiites from the Saar-Nahe trough, SW Germany
1973
The Hirschberg and Rodern diatremes, within the Permian Saar-Nahe trough, SW Germany, are composed chiefly of basaltic tuffs, with associated small intrusions of K-rich tholeiites. Several tholeiite bodies carry 2–20 mm crystals of magnesian clinopyroxene and orthopyroxene, the latter containing up to 5.5% Al2O3 and often extensively resorbed and rimmed by fine-grained olivine and clinopyroxene. Experimental duplication of these pyroxenes has been achieved under conditions of Pload=6–10 kb, T=1280–1080° C and 2–4 wt.-% H2O, confirming that they represent a rare occurence of high pressure phenocrysts in tholeiitic basalts. These conditions of pyroxene crystallization also place constraints o…
Melt evolution beneath a rifted craton edge: 40Ar/39Ar geochronology and Sr-Nd-Hf-Pb isotope systematics of primitive alkaline basalts and lamprophyr…
2016
A new high-precision Ar-40/Ar-39 anorthoclase feldspar age of 176.7 +/- 0.5 Ma (2-sigma) reveals that small-volume alkaline basaltic magmatism occurred at the rifted SW margin of the Baltic Shield in Scania (southern Sweden), at a time of global plate reorganization associated with the inception of Pangea supercontinent break-up. Our combined elemental and Sr-Nd-Hf-Pb isotope dataset for representative basanite and nephelinite samples (>8 wt.% MgO) from 16 subvolcanic necks of the 30 by 40 km large Jurassic volcanic field suggests magma derivation from a moderately depleted mantle source (Sr-87/(86)Sri = 0.7034-0.7048; epsilon Nd-i = +4.4 to +5.2; epsilon Hf-i = +4.7 to +8.1; Pb-206/(204)Pb…
The composition of near-solidus melts of peridotite in the presence of CO2 and H2O between 40 and 60 kbar
2009
Abstract Partial melting experiments at 40, 50 and 60 kbar pressure on three peridotite compositions with 0.5–0.63 wt.% H2O and 2.0–3.2 wt.% CO2 added indicate melting temperatures only marginally above continental geotherms. Most experiments were performed on a composition with 1.5 wt.% K2O added, which causes a further decrease of about 40 °C in melting temperature. Melts progress gradually from carbonate-rich to carbonated silicate in composition: near-solidus melts have Ca/(Ca + Mg) of 0.46–0.53, which fall to 30 wt.%) and Al2O3 ( 9 wt.%) and concomitant decrease in CaO (> 20 to Partial melts of peridotite with CO2 and H2O are too low in MgO to resemble kimberlites, but will act as ef…
Geodynamic Setting of the Tertiary Hocheifel Volcanism (Germany), Part II: Geochemistry and Sr, Nd and Pb Isotopic Compositions.
2007
Major and trace element as well as isotopic compositions on 26 volcanic rocks from the Tertiary Hocheifel volcanic field and for comparison from Upper Rhine Graben occurrences (western Central European Volcanic Province) were measured in order to provide geochemical evidence for the geodynamic setting of the Tertiary Eifel volcanism. Except for a few differentiated lavas there are mainly basanitic compositions. These rocks were produced by low degree partial melting of a previously metasomatized garnet peridotite source at pressures and temperatures corresponding to depths of about 75 to 90 km. In contrast to the differentiated lavas, most of the basanites are not significantly affected by …
Designing fluorous domains. Synthesis of a series of pyridinium salts bearing a perfluoroalkylated azole moiety
2006
The synthesis of a series of N-methylpyridinium salts bearing a perfluoroalkylated 1,2,4-oxadiazole or 1,2,4-triazole moiety is reported. X-Ray structures of representative perfluoroalkyl-triazolylpyridine (15) and methyl- pyridinium iodide salt (5a) are reported. Their crystal packing clearly shows segregation between the aromatic and parallel double layer fluorinated regions.
Dielectric investigations of pure and mixed fluorocarbons in their condensed phases
1991
We review recent work and present new results on the liquid and solid fluocarbons CMF3 with M = H, F, Cl, Br, CH3, and CF3. The pure compounds as well as several series of binary mixtures were investigated using dielectric measurements. The permittivities of the non-hydrogenatcd non-polar and polar liquids could be described using the Clausius-Mosotti and the Onsager equation, respectively. In CHF3 and C2H3F3 hydrogen bridging leads to deviations from this simple behavior. The trends in the miscibility of four series of fluorocarbon mixtures are in qualitative accord with regular solution theory. The geometrical shapes of the compounds dominate the degrees of order below their melting point…