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Artykuły w czasopismach na temat "K-rich melt":
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Solovova, I. P., i A. V. Girnis. "Silicate–carbonate liquid immiscibility and crystallization of carbonate and K-rich basaltic magma: insights from melt and fluid inclusions". Mineralogical Magazine 76, nr 2 (kwiecień 2012): 411–39. http://dx.doi.org/10.1180/minmag.2012.076.2.09.
Streszczenie:
AbstractThis paper reports an investigation of the crystallization products of K-rich silicate and carbonate melts trapped as melt inclusions in clinopyroxene phenocrysts from the Dunkeldyk alkaline igneous complex in the Tajik Republic. Heating experiments on the melt inclusions suggest that the carbonate melt was formed by liquid immiscibility at 1180°C and ∼0.5 GPa. The carbonate-rich inclusions are dominated by Sr-bearing calcite, and rich in incompatible elements. Most of the silicate minerals are SiO2-poor and rich in K, Ba and Ti. Leucite, kalsilite and aegirine are the earliest magmatic minerals. High Ba and Ti contents in the melt resulted in the crystallization of Ba-rich K-feldspar, titanite, perovskite and Ti-bearing garnet, and the rare Ba-Ti silicates fresnoite and delindeite. The last minerals to crystallize from volatile-rich melts and fluids were aegirine, götzenite, K-Ba- and Ca-Sr-bearing zeolites, fluorite and strontium-rich baryte. Interaction of the early minerals with residual melts and fluids produced Ba-rich phlogopite and Sr-rich apatite.
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HAMADA, MORIHISA, i TOSHITSUGU FUJII. "H2O-rich island arc low-K tholeiite magma inferred from Ca-rich plagioclase-melt inclusion equilibria". GEOCHEMICAL JOURNAL 41, nr 6 (2007): 437–61. http://dx.doi.org/10.2343/geochemj.41.437.
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Lloyd, F. E., A. D. Edgar, D. M. Forsyth i R. L. Barnett. "The paragenesis of upper-mantle xenoliths from the Quaternary volcanics south-east of Gees, West Eifel, Germany". Mineralogical Magazine 55, nr 378 (marzec 1991): 95–112. http://dx.doi.org/10.1180/minmag.1991.055.378.08.
Streszczenie:
AbstractGroup I xenoliths, orthopyroxene-rich and orthopyroxene-free, contain Cr-spinel and clinopyroxene ± phlogopite, and occur together with Group II clinopyroxenites ± Ti-spinel ± phlogopite in K-mafic pyroclastics southeast of Gees. The petrography and clinopyroxene chemistry of orthopyroxene-rich (opx-rich sub-group) Group I xenoliths is consistent with an ‘original’ harzburgitic mantle that has been transformed to lherzolite by the addition of endiopside. In harzburgites, orthopyroxenes are reacting to diopside + olivine + alkali-silicate melt, and, by inference, the orthopyroxene-free (opx-free subgroup) Group I, dunite-wehrlite series can be linked to the opx-rich sub-group via this reaction. Progressive enrichment of dunitic material in endiopside-diopside has resulted in the formation of wehrlite. Phlogopite is titaniferous and occurs as a trace mineral in opx-rich, Group I xenoliths, whereas substantial phlogopite vein-networks are confined to the opx-free sub-group (dunite-wehrlite series). Interstitial, alkali-felsic glass occurs are veins within, and as extensions of, the phlogopite networks. Clinopyroxenes in phlogopite-veined xenoliths are decreased in Mg/(Mg + FeTotal) (mg) and Cr and increased in Ti, Al and Ca, compared with clinopyroxenes in xenoliths which have trace phlogopite. It is proposed that harzburgitic and dunitic mantle has been infiltrated by a Ca- and alkalirich, hydrous silicate melt rather than an ephemeral carbonatite melt. Dunite has been transformed to phlogopite wehrlite by the invasion of a Ca-, Al-, Ti- and K-rich, hydrous silicate melt. Ca-activity was high initially in the melt and was reduced by clinopyroxene precipitation. This resulted in enhanced K-activity which led to phlogopite veining of clinopyroxene-rich mantle. Group II phlogopite clinopyroxenites contain Ti-spinel and salites that are distinct in their Ti, Al and Cr contents from endiopsides and diopsides in Group I xenoliths. It is unlikely that these Group II xenoliths represent the culmination of the infiltration processes that have transformed dunite to wehrlite, nor can they be related to the host melt. These xenoliths may have crystallised from Ca- and K-bearing, hydrous silicate melts in mantle channelways buffered by previously precipitated clinopyroxene and phlogopite. Gees lherzolites contain pyroxenes and spinel with distinctly lower Al contents than these same minerals in lherzolites described previously from other West Eifel localities, which may reflect a distinctive lithology and/or processes of modification for the Gees mantle.
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Kozieł, T., J. Latuch i A. Zielińska-Lipiec. "Structure of the Amorphous-Crystalline Fe66Cu6B19Si5Nb4 Alloy Obtained by the Melt-Spinning Process". Archives of Metallurgy and Materials 58, nr 2 (1.06.2013): 601–5. http://dx.doi.org/10.2478/amm-2013-0044.
Streszczenie:
This paper presents structure investigations of the rapidly cooled Fe66Cu6B19Si5Nb4 alloy. A proper selection of chemical composition enabled in-situ formation of the amorphous-crystalline composite during the melt spinning process. Liquid phase separation into the Fe-rich and the Cu-rich phases was confirmed. The microstructures of alloy, melt-spun from 1723 and 1773 K, are composed of the Fe-rich amorphous matrix and Cu-rich spherical crystalline precipitates. For the higher melt-ejection temperature, no coarse precipitates could be observed. Amorphous nature of the Fe-rich matrix was confirmed by presence of a broad diffraction maximum on the X-ray diffraction patterns, a halo ring on the electron diffraction pattern as well as presence of exothermic effects, related to the crystallization of the Fe-rich amorphous matrix, in the differential scanning calorymetry. Beside presence of copper, revealing positive heat of mixing with iron, relatively large supercooled liquid region, was noticed.
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Xu, Man, Zhicheng Jing, Suraj K. Bajgain, Mainak Mookherjee, James A. Van Orman, Tony Yu i Yanbin Wang. "High-pressure elastic properties of dolomite melt supporting carbonate-induced melting in deep upper mantle". Proceedings of the National Academy of Sciences 117, nr 31 (20.07.2020): 18285–91. http://dx.doi.org/10.1073/pnas.2004347117.
Streszczenie:
Deeply subducted carbonates likely cause low-degree melting of the upper mantle and thus play an important role in the deep carbon cycle. However, direct seismic detection of carbonate-induced partial melts in the Earth’s interior is hindered by our poor knowledge on the elastic properties of carbonate melts. Here we report the first experimentally determined sound velocity and density data on dolomite melt up to 5.9 GPa and 2046 K by in-situ ultrasonic and sink-float techniques, respectively, as well as first-principles molecular dynamics simulations of dolomite melt up to 16 GPa and 3000 K. Using our new elasticity data, the calculated VP/VSratio of the deep upper mantle (∼180–330 km) with a small amount of carbonate-rich melt provides a natural explanation for the elevated VP/VSratio of the upper mantle from global seismic observations, supporting the pervasive presence of a low-degree carbonate-rich partial melt (∼0.05%) that is consistent with the volatile-induced or redox-regulated initial melting in the upper mantle as argued by petrologic studies. This carbonate-rich partial melt region implies a global average carbon (C) concentration of 80–140 ppm. by weight in the deep upper mantle source region, consistent with the mantle carbon content determined from geochemical studies.
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Shen, Xiao, Shuiqing Liu, Xin Wang, Chunxiang Cui, Pan Gong, Lichen Zhao, Xu Han i Zirui Li. "Effect of Cooling Rate on the Microstructure Evolution and Mechanical Properties of Iron-Rich Al–Si Alloy". Materials 15, nr 2 (6.01.2022): 411. http://dx.doi.org/10.3390/ma15020411.
Streszczenie:
The mechanical properties of iron-rich Al–Si alloy is limited by the existence of plenty of the iron-rich phase (β-Al5FeSi), whose unfavorable morphology not only splits the matrix but also causes both stress concentration and interface mismatch with the Al matrix. The effect of the cooling rate on the tensile properties of Fe-rich Al–Si alloy was studied by the melt spinning method at different rotating speeds. At the traditional casting cooling rate of ~10 K/s, the size of the needle-like β-Al5FeSi phase is about 80 μm. In contrast, the size of the β-Al5FeSi phase is reduced to 500 nm and the morphology changes to a granular morphology with the high cooling rate of ~104 K/s. With the increase of the cooling rate, the morphology of the β-Al5FeSi phase is optimized, meanwhile the tensile properties of Fe-rich Al–Si alloy are greatly improved. The improved tensile properties of the Fe-rich Al-Si alloy is attributed to the combination of Fe-rich reinforced particles and the granular silicon phase provided by the high cooling rate of the melt spinning method.
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Nosova, Anna A., Ludmila V. Sazonova, Alexey V. Kargin, Elena O. Dubinina i Elena A. Minervina. "Mineralogy and Geochemistry of Ocelli in the Damtjernite Dykes and Sills, Chadobets Uplift, Siberian Craton: Evidence of the Fluid–Lamprophyric Magma Interaction". Minerals 11, nr 7 (5.07.2021): 724. http://dx.doi.org/10.3390/min11070724.
Streszczenie:
The study reports petrography, mineralogy and carbonate geochemistry and stable isotopy of various types of ocelli (silicate-carbonate globules) observed in the lamprophyres from the Chadobets Uplift, southwestern Siberian craton. The Chadobets lamprophyres are related to the REE-bearing Chuktukon carbonatites. On the basis of their morphology, mineralogy and relation with the surrounding groundmass, we distinguish three types of ocelli: carbonate-silicate, containing carbonate, scapolite, sodalite, potassium feldspar, albite, apatite and minor quartz ocelli (K-Na-CSO); carbonate–silicate ocelli, containing natrolite and sodalite (Na-CSO); and silicate-carbonate, containing potassium feldspar and phlogopite (K-SCO). The K-Na-CSO present in the most evolved damtjernite with irregular and polygonal patches was distributed within the groundmass; the patches consist of minerals identical to minerals in ocelli. Carbonate in the K-Na-CSO are calcite, Fe-dolomite and ankerite with high Sr concentration and igneous-type REE patterns. The Na-CSO present in Na-rich damtjernite with geochemical signature indicates the loss of the carbonate component. Carbonate phases are calcite and Fe-dolomite, and they depleted in LREE. The K-SCO was present in the K-rich least-evolved damtjernite. Calcite in the K-SCO has the highest Ba and the lowest Sr concentration and U-shaped REE pattern. The textural, mineralogical and geochemical features of the ocelli and their host rock can be interpreted as follows: (i) the K-Na-CSO are droplets of an alkali–carbonate melt that separated from residual alkali and carbonate-rich melt in highly evolved damtjernite; (ii) the Na-CSO are droplets of late magmatic fluid that once exsolved from a melt and then began to dissolve; (iii) the K-SCO are bubbles of K-P-CO2 fluid liberated from an almost-crystallised magma during the magmatic–hydrothermal stage. The geochemical signature of the K-SCO carbonate shows that the late fluid could leach REE from the host lamprophyre and provide for REE mobility.
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Vapnik, Ye. "Melt inclusions in granitoids of the Timna Igneous Complex, Southern Israel". Mineralogical Magazine 62, nr 1 (luty 1998): 29–40. http://dx.doi.org/10.1180/002646198547440.
Streszczenie:
AbstractHigh temperature microthermometry and Scanning Electron Microprobe (SEM) analyses were used to study natural magmatic remnants in quartz crystals in granitoids from the Timna Igneous Complex, southern Israel, and to constrain physicochemical parameters during their crystallization. For the porphyritic granite, alkali granite and quartz monzodiorite, liquidus temperatures are 710–770, 770–830 and 770–840°C, respectively; solidus temperatures are 690–770, 710–790 and 770°C, respectively. Pressures during crystallization and water content in the magmas were determined using the phase diagram of the modal granite system. The determined P-T-conditions are typical for water-saturated granitoid magmas (>4–8 wt.%) generated and crystallized at a shallow crustal level.SEM data on melt inclusions support conclusions of previous investigations on two types of granitoid magmas exposed in the Timna Igneous Complex: the porphyritic and alkali granites. Different trends of crystallization are proposed for these granites. Crystallization of the porphyritic granite started with cotectic crystallization of plagioclase and terminated in residual K-feldspar-rich crystallization; crystallization of the alkali granite took place at higher temperatures, starting with K-rich alkali-feldspar crystallization and terminating in residual Na-rich eutectic crystallization.Parameters not available from other sources — temperature and pressure of the liquidus and solidus stages, water content, trends of crystallization — were obtained for the porphyritic and alkali granites.
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Hurai, V., M. Huraiová, P. Konečný i R. Thomas. "Mineral-melt-fluid composition of carbonate-bearing cumulate xenoliths in Tertiary alkali basalts of southern Slovakia". Mineralogical Magazine 71, nr 1 (luty 2007): 63–79. http://dx.doi.org/10.1180/minmag.2007.071.1.63.
Streszczenie:
AbstractTwo types of carbonatic cumulate xenoliths occur in alkali basalts of the northern part of the Carpatho-Pannonian region, Central Europe. One is dominated by Ca-Fe-Mg carbonates with randomly distributed bisulphide globules (Fe1+xS2, x = 0–0.1), Mg-Al spinel, augite, rhönite, Ni-Co-rich chalcopyrite, and a Fe(Ni,Fe)2S4 phase. The second, carbonatic pyroxenite xenolith type, is composed of diopside, subordinate fluorapatite, interstitial Fe-Mg carbonates, and accessory K-pargasite, F-Al-rich ferroan phlogopite, Mg-Al spinel, albite and K-feldspar. All accessory minerals occur in ultrapotassic dacite-trachydacite glass in primary silicate melt inclusions in diopside, together with calcio-carbonatite and CO2-N2-CO inclusions. Textural evidence is provided for multiphase fluid-melt immiscibility in both xenolith types. The carbonatic pyroxenite type is inferred to have accumulated from differentiated, volatile-rich, ultrapotassic magma derived by a very low-degree partial melting of strongly metasomatized mantle. Mineral indicators point to a genetic link between the carbonatite xenolith with olivine-fractionated, silica-undersaturated alkalic basalt ponded at the mantle-crust boundary.
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Balcone-Boissard, Hélène, Don R. Baker, Benoit Villemant, Jean Cauzid, Georges Boudon i E. Deloule. "Br diffusion in phonolitic melts: Comparison with fluorine and chlorine diffusion". American Mineralogist 105, nr 11 (1.11.2020): 1639–46. http://dx.doi.org/10.2138/am-2020-7372.
Streszczenie:
Abstract Bromine diffusion was measured in two natural phonolitic melts: (1) a K2O-rich (~10 wt%) one synthesized from the white pumice phase of the 79 AD eruption of Vesuvius (Italy), and (2) a Na2O-rich (~10 wt%) one corresponding to the most differentiated melt of the 12 000 BC eruption of the Laacher See (Germany). Experiments were performed at 0.5 and 1.0 GPa, 1250 to 1450 °C, at anhydrous and hydrous (2.65 ± 0.35 wt% of dissolved water) conditions. Experiments conducted with the diffusion-couple technique in the piston cylinder were performed with only bromine diffusing and with the simultaneous diffusion of a halogen mixture (F, Cl, Br) to evaluate the interactions between the halogens during diffusion. The diffusion profiles of Br were measured by X-ray fluorescence using synchrotron radiation microprobe (SYXRF), ID18F, at the European Synchrotron Radiation Facility (ESRF, France). Bromine diffusion displays Arrhenian behavior under anhydrous conditions that is similar when it diffuses alone and when it diffuses with F and Cl. The Br diffusion coefficients range between 2 × 10–12 m2/s at 1250 °C and 1.5 × 10–11 m2/s at 1450 °C for the Na-rich melt and between 3 × 10–12 m2/s at 1250 °C and 2.5 × 10–11 m2/s at 1450 °C for the K-rich melt, at 1.0 GPa. Although Br mobility is independent of F and Cl in anhydrous phonolitic melts, its behavior may be dependent on the dominant alkali in the melt, as previously observed for Cl, but not F. For hydrous experiments, although the data are scattered, the Br diffusivity increases slightly with water and the Na/K ratio seems to influence Br diffusivity. Similarly to noble gases, halogen diffusivity at a given temperature in the phonolitic melts appears related to the ionic porosity of the silicate structure. Compared to basaltic melt, Br diffusivities are approximately one order of magnitude lower in the Na-phonolite melt, because of the difference of the pre-exponential factor. Br mobility appears to be decoupled from melt viscosity, considering the results here.
Części książek na temat "K-rich melt":
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Garcia, Amauri, Pedro Goulart, Felipe Bertelli, José Spinelli i Noé Cheung. "Hypoeutectic Al–Fe Alloys: Formation and Characterization of Intermetallics by Dissolution of the Al Matrix". W Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000305.
Streszczenie:
A careful technique of dissolution of the Al-rich phase is conducted in hypoeutectic Al–Fe alloys samples, which were solidified under a wide range of cooling rates envisaging deeper investigations on the skeletal arrangement of either Al6Fe intermetallic fibers or Al3Fe plates, and their dependence on solidification thermal parameters. The experiments were carried out with hypoeutectic Al–Fe alloys, subjected to equilibrium solidification from the melt, steady-state solidification (Bridgman growth), transient directional solidification in water-cooled and air-cooled molds and rapid solidification (laser remelting), thus permitting a significant range of microstructural scales to be examined. It is shown that Al6Fe prevails for cooling rates >1.5 K/s, and that a short zone of coexistence of Al3Fe and Al6Fe phases exists for cooling rates <1.5 K/s, which is rapidly replaced with the prevalence of Al3Fe intermetallics with further decrease in cooling rate. In contrast, even with high values of cooling rate, typical of the laser remelting process, the Al–Al3Fe eutectic is shown to prevail.
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Leys, Clyde, Adam Schwarz, Mark Cloos, Sugeng Widodo, J. Richard Kyle i Julius Sirait. "Chapter 29: Grasberg Copper-Gold-(Molybdenum) Deposit: Product of Two Overlapping Porphyry Systems". W Geology of the World’s Major Gold Deposits and Provinces, 599–620. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.29.
Streszczenie:
Abstract The supergiant Grasberg porphyry deposit in Papua, Indonesia (5.26 Gt @ 0.61% Cu and 0.57 g/t Au, with no cutoff applied) is hosted by the Grasberg Igneous Complex that fills an upward-flared diatreme ~1,800 m wide at the 4,250-m surface elevation. The Grasberg Igneous Complex is emplaced into folded and strike-slip faulted Tertiary and older sediments and comprises 3.6 to 3.3 Ma Dalam monzodiorite intrusions and subordinate volcanic rocks occupying much of the pipe, the central 3.2 Ma Main Grasberg intrusion, and the NW-SE-trending 3.2 to 3.0 Ma Kali dikes. The Grasberg Igneous Complex contains two porphyry systems: Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold. The Gajah Tidur intrusion belongs to the Dalam igneous group and is a 3.4 Ma porphyritic monzonite with its top at a 2,750-m elevation; it is overprinted by an extensive, domal, quartz stockwork, with a low-grade and intensely phyllic-altered core, surrounded by molybdenite-bearing veins, with a pre-Main Grasberg Re-Os age, as well as chalcopyrite and overprinting pyrite-covellite veins. The strongly potassic-altered, Main Grasberg monzodiorite porphyry extends from surface to the 2,700-m elevation and is overprinted by a cylindrical, ~1-km-diameter, intense quartz-magnetite stockwork cut by abundant chalcopyrite-bornite veins with rare molybdenite dated at 3.09 Ma. A 700-m-wide annulus of chalcopyrite overprinted by pyrite-covellite-mineralized phyllic alteration surrounds the stockwork. Altered and mineralized Main Grasberg and surrounding Dalam rocks were subsequently wedged apart by the largely unmineralized Kali dikes. Gold is predominantly associated with the Main Grasberg porphyry system where it occurs as 1- to 150-µm (avg ~15 µm) native gold inclusions within chalcopyrite and bornite. Melt and fluid inclusions from Main Grasberg stockwork quartz veins, which exhibit crack-seal textures, comprise K-feldspar-rich silicate melt, sulfide melt, virtually water-free salt melt, and coexisting hypersaline and vapor-rich fluids. Factors important in forming the Grasberg deposit include the following: (1) generation of highly oxidized fertile magma in a postsubduction tectonic setting; (2) efficient extraction of metals from the parental magma chamber; (3) prolonged maintenance of a fluid-accumulating cupola in a strike-slip structural setting that delivered multiple overlapping discharges of metal-rich fluid; (4) highly focused fluid flow into a narrow, permeable stockwork zone in which a steep temperature gradient enabled highly efficient copper and gold precipitation and led to high ore grades; (5) limited dilution by postmineral intrusions; (6) the youthfulness of the deposit minimized erosion and resulted in preservation of nearly all the high-grade Main Grasberg porphyry orebody; and (7) the proximity of the two porphyry centers enables them to be mined as a single, large deposit. The Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold porphyry centers overlap in space and formed within ~250,000 years of one another. However, their distinct metal endowment, depth of emplacement, and geometry indicate that they formed under different magmatic, hydrothermal, and structural conditions, which are the subject of ongoing research.
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Gioncada, A., P. Fulignati, L. Vezzoli, R. Omarini, D. Bosch, O. Bruguier, R. Mazzuoli i V. Lopez-Azarevich. "Magmatic Sulfides from the Rincón-Portezuelo de las Ánimas Volcanic Complex, Northwest Argentina: Insights on Magma Fertility and Comparison with Mineralized Volcanic Systems". W Tectonomagmatic Influences on Metallogeny and Hydrothermal Ore Deposits: A Tribute to Jeremy P. Richards (Volume I), 101–20. Society of Economic Geologists, 2021. http://dx.doi.org/10.5382/sp24.07.
Streszczenie:
Abstract The composition and fate of magmatic sulfides are some of the most critical factors invoked to play a role in the chalcophile metal fertility of arc magmas. Examination of magmatic sulfide accessory minerals in nonmineralized volcanic systems may help to understand the behavior of chalcophile metals at sulfide saturation. This study presents compositional data on magmatic sulfides in lavas of the late Miocene Rincón-Portezuelo de las Ánimas Volcanic Complex, northwest Argentina. This is the easternmost magmatic occurrence in the back arc of the Southern Central Andes, at 27°S, about 75 km northeast from the world-class Bajo de la Alumbrera porphyry Cu-Au deposit. At this latitude the late Miocene volcanic activity migrated eastward as a consequence of the shallowing slab subduction. Both copper-rich and pyrrhotite magmatic sulfide inclusions have been identified in the Rincón-Portezuelo de las Ánimas volcanic suite, straddling the high K calc-alkaline–shoshonite boundary. We discuss the sulfide composition in the framework of magmatic evolution and in comparison to the metal content of magmatic sulfides of the coeval Farallón Negro Volcanic Complex, associated with the Bajo de la Alumbrera porphyry Cu-Au and other mineralized systems. The results show that sulfide liquid, exsolved from silicate melts of intermediate composition, stores Cu, Pb, Ag, and Bi in crystal mushes, reducing the mineralizing potential of residual melts while fertilizing the middle-upper crust. Gold behavior seems to be controlled by additional mechanisms, linked to the magma source or to an early partitioning into an S-bearing fluid phase. The high Au/Cu ratio of sulfides formed as monosulfide solid solution may be associated with the potassic character of the magmas in this sector of the Central Andes.
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Jordan, Carl F. "The Interface Between Economics and Nutrient Cycling in Amazon Land Development". W The Biogeochemistry of the Amazon Basin. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195114317.003.0013.
Streszczenie:
Most of the terra firme soils in the Amazon are highly weathered, highly leached, have low capacity for retaining nutrients against the continual leaching and weathering of the tropical climate, and are classified as Oxisols and Ultisols, soil types with extremely low fertility (see Cuevas, this volume). The naturally occurring forests of the region maintain a high production of wood and leaves through very efficient recycling of nutrients from decomposing litter to roots in a root-humus layer on top of the mineral soil or near its surface. The decomposing litter is important not only as a source of nutrients, but as a source of organic acids which prevent phosphorus fixation in the iron- and aluminium-rich soils of the Amazon. When forests on Amazonian terra firme soils are cut and burned, and the soils used for agriculture, litter, and humus are rapidly oxidized and destroyed. As a result, the potassium remaining from the original forest is quickly leached, the nitrogen is volatilized, and the phosphorus is immobilized in the mineral soil. This is one of the most important reasons that crop production can be carried out for only a few years under shifting cultivation. It is not just small scale agriculture that is limited by the low fertility of Amazonian soils. In the past, almost all types of development that destroy the nutrient conserving mechanisms of the forest have suffered financially. Two examples are given here to illustrate. In 1967, one of the largest conversions of tropical forest to pulp plantation began near the junction of the Jarí and Amazon rivers, in the state of Pará, Brazil (Time, 1976). The “Jarí” project was initiated and financed by Daniel K. Ludwig, one of the world’s richest men, and owner of numerous international corporations. Ludwig had anticipated a global shortage of wood fiber for pulp, and to meet this shortage, he and his advisors selected a site that they believed had high potential for pulp production (Time 1979, Kinkead 1981). By 1981, the total investment in the 12,000 km2 tract of land was approximately $1 billion (Kinkead 1981). Ludwig’s advisors recommended melina (Gmelina arborea) as the best species to plant.
Streszczenia konferencji na temat "K-rich melt":
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Shalileh, Soroosh, i Boris Mirkin. "Community detection in feature-rich networks to meet K-means". W ASONAM '21: International Conference on Advances in Social Networks Analysis and Mining. New York, NY, USA: ACM, 2021. http://dx.doi.org/10.1145/3487351.3488356.
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Ramokgaba, Lesego, Stephen Foley i Geoffrey Howarth. "Modification of harzburgite to K-rich dolomite-bearing peridotite from the Kaapvaal craton, South Africa: Evidence of metasomatism by carbonate-silicate incipient melts". W Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.11555.
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Wilkes, Colin, Hukam C. Mongia i Chandran B. Santanam. "An Ultra-Low NOx Combustion System for a 3.5 MW Industrial Gas Turbine". W ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/90-gt-083.
Streszczenie:
This paper presents the results obtained from a 1/8 th scale rich-quench-lean (RQL) combustor designed for ultra-low NOx operation running at Allison 501-K engine simulated full and part load conditions. The goal of the test program was to demonstrate the capability of the combustor to limit oxides of nitrogen (NOx) emissions to less than 10 ppmv and provide simultaneous control of carbon monoxide (CO) emissions to below 50 ppmv, both corrected to 15% oxygen. The tests were conducted on a refractory-lined bench scale combustor developed originally to support the advanced coal fired gas turbine program which is sponsored in part by the Department of Energy (DoE) Morgantown Energy Technology Center (METC). Measurements were made of NOx and CO emissions from natural gas (NG) and distillate fuel number 2 (DF#2) with water injection at simulated full and part power operation over a range of rich, quench and lean zone temperatures. The results show that the NOx goals of the test program were met and that CO emissions could be further controlled to less than 10 ppmvd on both fuels. The thermodynamic constraints of the system, the airflow splits and water injection rate requirements are discussed together with the combustor general design parameters. Estimates are also made for the required steam injection rate to produce the same NOx and CO emission levels.
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Witwer, Keith. "Preliminary Demonstration of GeoMelt Treatment of Hanford’s K-Basin Sludge". W ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2011. http://dx.doi.org/10.1115/icem2011-59004.
Streszczenie:
The U.S. Department of Energy (DOE) and CH2M Hill Plateau Remediation Company (CHPRC) are seeking a waste treatment solution for sludge stored in the K-Basin spent fuel pond at the Hanford Nuclear Site, in Washington State, USA. This sludge is a Remote Handled Transuranic (RHTRU) waste destined for final disposal at the Waste Isolation Pilot Pant (WIPP) in New Mexico. Removal of the sludge from the K-Basin and transport for interim storage at the Hanford Site is referred to as Phase 1 in this process. Phase 2 is defined as the treatment and packaging of the sludge such that it can be transported and disposed at the WIPP. This paper discusses work in support of Phase 2. ISI’s GeoMelt ICV process is ideally suited to treating a heterogeneous sludge that is rich in uranium metal and which contains a mixture of other fuel derived products, earthen materials, and miscellaneous items (operational debris, resin, etc). GeoMelt can quickly and efficiently treat small drum load batches and will fully destroy organics, oxidize reactive metals, and permanently immobilize radioactive constituents within a high-integrity vitrified product that will meet or exceed all WIPP acceptance criteria. The GeoMelt Technology has an extensive experience base, having treated more waste by vitrification than any other company in the world (25,500 metric tons). The equipment tested for this Project phase constituted the front end, or Sludge Pretreatment and Transport steps, of the proposed GeoMelt process. These components first focused on an engineering scale (22-liter), followed by testing with a full-scale (130-liter), horizontal rotary plow dryer/mixer. The dryer removes water from the sludge, via external heating and under reduced pressure, and mixes it with glass forming minerals (GFM) prior to treatment in the GeoMelt ICV system. Testing was first performed in July and September 2010 using a 22-liter drying system, which demonstrated a baseline drying technique and allowed an assessment of the resulting physical properties before, during, and after drying/mixing. Full-scale testing using a 130-liter dryer and condensate system was then performed in October 2010. An Operational Acceptance Test (OAT) of the equipment, followed by four “Dryer Holdup” tests and three “GFM Cleanout” tests were performed. Each of the Project Test Objectives was successfully met. Both the 22-liter engineering-scale and the 130-liter full-scale steam jacketed, horizontal plow, dryer are shown to dry and mix 5-vol% solids K-Basin sludge and GFM without difficulty. These test results, combined with previous treatability testing in 2004 wherein successful GeoMelt vitrification of a K-Basin sludge simulant was demonstrated, confirm the efficacy of the overall treatment process towards providing an immediate solution to the final disposition of K Basin Sludge.
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Schmalhofer, Christoph A., Peter Griebel i Manfred Aigner. "Influence of Carrier Air Preheating on Autoignition of Inline-Injected Hydrogen-Nitrogen Mixtures in Vitiated Air of High Temperature". W ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63249.
Streszczenie:
Gas turbines will play a significant role in future power generation systems because they provide peak capacity due to their fast start-up capability and high operational flexibility. However, in order to meet the COP 21 goals, de-carbonization of as turbine fuels is required. Compared to natural gas operation, autoignition and flashback risks in gas turbines operated on hydrogen-rich fuels are higher which has to be taken into account for a proper gas turbine design. From investigations of these phenomena at relevant operating conditions with appropriate measurement techniques, e.g. high-speed imaging, the understanding of the non-stationary processes occurring during autoignition can be improved and design guidelines for a safe and reliable gas turbine operation can be derived. The present study investigates the influences of elevated carrier-air preheating temperatures and hydrogen fuel volume fractions on autoignition at hot gas temperatures higher than 1100 K and pressures of 15 bar. An in-line co-flow injector is used to inject the hydrogen-nitrogen fuel mixtures. The formation, temporal and spatial development of autoignition kernels at high-temperature vitiated air conditions, e.g. relevant to reheat combustor operation, are studied. The experiments were conducted in an optically accessible mixing section of a generic reheat combustor. The hydrogen-nitrogen fuel mixtures of up to 70 vol. % hydrogen are injected in-line into the mixing section along with the carrier-air which was preheated to temperatures between 303 K and 703 K. High-speed imaging was used to detect the autoignition kernels and their temporal and spatial development from luminescence signals. Particle Image Velocimetry measurements were conducted to obtain the velocity distribution in the mixing section at autoignition conditions. The influences of vitiated air temperatures and carrier preheating temperatures on autoignition and flame stabilisation limits are shown, alongside the spatial distribution of different types of autoignition kernels, developing at different stages of the autoignition process. The development of autoignition kernels could be linked to the shear layer development derived from global experimental conditions.
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Fink, R., A. Hupfer i D. Rist. "Non-Intrusive Measurements of a LPP Combustor Under Elevated Pressure Conditions". W ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30078.
Streszczenie:
To meet increasingly tight regulations on emission control appropriate combustor designs need to be developed. With different combustion concepts like RQL (Rich Quench Lean) and LPP (Lean Premixed Prevaporized) it has been proven that it is possible to reach the objective of a significant reduction of the NOX emissions. To gain further insight into the real combustion process it is of importance to be able to “look into” the flame without interfering with the actual combustion process. At the combustion laboratory of the Institute of Flight Propulsion at Munich University of Technology a combustion test facility is set up to study combustion characteristics under pressure up to 6 bar and inlet airflow temperature up to 650 K. A newly designed LPP concept was adapted into an optically accessible model combustion chamber. The objective of the study was to operate the LPP combustor under semi-realistic conditions and to obtain more knowledge on the influence of pressure on the combustion process. With suitable non-intrusive laser-spectroscopic measuring techniques like LIF (Laser Induced Fluorescence) the fuel spray, the nitric oxides and the hydroxyl radical were detected in several planes parallel to the combustor axis at different combustor pressures. As expected the pressure has a strong effect on droplet distribution and evaporation. Also with increasing pressure it was possible to operate the combustor under leaner conditions. A strong dependence on pressure of the formation of nitric oxides was detected. To quantify these results samples with a water-cooled probe were taken, analyzed and compared with the non intrusive measurements.
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Ngũgĩ, John Mbũrũ, Sandra Richter, Marina Braun-Unkhoff, Clemens Naumann i Uwe Riedel. "A Study on Fundamental Combustion Properties of Trimethyl Orthoformate: Experiments and Modeling". W ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-83029.
Streszczenie:
Abstract Trimethyl orthoformate (TMOF: HC(OCH3)3) has recently been examined as a viable biofuel. TMOF is a branched isomer of oxymethylene ether-2 (OME2) that, due to its high oxygen content and lack of direct carbon-carbon bonds, considerably reduces the formation of soot particles. To meet the challenges of a more flexible and sustainable power generation, a detailed understanding of its combustion properties is essential for its safe and efficient utilization, neat or in blends. In this work, two fundamental combustion properties of TMOF were studied: (i) Auto-ignition of TMOF / synthetic air mixtures (φ = 1.0; diluted 1:5 with N2) using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) Laminar burning velocities of TMOF / air mixtures using the cone angle method at ambient and elevated pressures of 3 and 6 bar. Furthermore, the impact of TMOF addition to a gasoline surrogate (PRF90) on ignition delay times was studied using the shock tube method at φ = 1.0, 1:5 dilution with N2, T = 900–2000 K, and at 4 bar. The experimental data sets have been compared with predictions of the in-house chemical kinetic reaction mechanism (DLR Concise mechanism) developed for interpreting the high-temperature combustion of a broad spectrum of different hydrocarbon fuels as well as oxygenated fuels, including TMOF. The results demonstrate that the ignition delay times of TMOF and OME2 are nearly identical for all pressures studied in the moderate-to high-temperature region. The results obtained for the blend indicate that ignition delay times of the TMOF / PRF90 blend are shorter than those of the primary reference fuel 90 (PRF90) at 4 bar. In the lean-to stoichiometric region, the results obtained for laminar burning velocities of TMOF and OME2 are similar. However, in the fuel-rich domain (φ > 1.0), laminar burning velocities for TMOF are noticeably lower, indicating a decreased reactivity. The model predictions based on the in-house model reveal a good agreement compared to the measured data within the experimental uncertainty ranges. In addition, sensitivity analyses regarding ignition delay times and laminar flame speeds were performed to better understand TMOF oxidation.
Raporty organizacyjne na temat "K-rich melt":
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Jacques, I. J., A. J. Anderson i S. G. Nielsen. The geochemistry of thallium and its isotopes in rare-element pegmatites. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328983.
Streszczenie:
The Tl isotopic and trace element composition of K-feldspar, mica, pollucite and pyrite from 13 niobium-yttrium-fluorine (NYF)-type and 14 lithium-cesium-tantalum (LCT)-type rare-element pegmatites was investigated. In general, the epsilon-205Tl values for K-feldspar in NYF- and LCT-type pegmatites increases with increasing magmatic fractionation. Both NYF and LCT pegmatites display a wide range in epsilon-205Tl (-4.25 to 9.41), which complicates attempts to characterize source reservoirs. We suggest 205Tl-enrichment during pegmatite crystallization occurs as Tl partitions between the residual melt and a coexisting aqueous fluid or flux-rich silicate liquid. Preferential association of 205Tl with Cl in the immiscible aqueous fluid may influence the isotopic character of the growing pegmatite minerals. Subsolidus alteration of K-feldspar by aqueous fluids, as indicated by the redistribution of Cs in K-feldspar, resulted in epsilon-205Tl values below the crustal average (-2.0 epsilon-205Tl). Such low epsilon-205Tl values in K-feldspar is attributed to preferential removal and transport of 205Tl by Cl-bearing fluids during dissolution and reprecipitation. The combination of thallium isotope and trace element data may be used to examine late-stage processes related to rare-element mineralization in some pegmatites. High epsilon-205Tl and Ga in late-stage muscovite appears to be a favorable indicator of rare-element enrichment LCT pegmatites and may be a useful exploration vector.