Relevant bibliographies by topics / Pyroxene

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Academic literature on the topic 'Pyroxene'

Author: Grafiati
Published: 4 June 2021
Last updated: 13 June 2025

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Journal articles on the topic "Pyroxene"

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Hall, R. P., D. J. Hughes, and L. Joyner. "Fe-enrichment in tholeiitic pyroxenes: complex two-pyroxene assemblages in Mesozoic dolerites, southern Tasmania." Geological Magazine 125, no. 6 (1988): 573–82. http://dx.doi.org/10.1017/s0016756800023396.

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AbstractThe pyroxene assemblages of four samples of ferrodolerite from the Mesozoic Mount Wellington sill of southern Tasmania are described. The pyroxenes of each sample define an Fe-enrichment trend equivalent to almost half of a Skaergaard-type pyroxene evolution trend. The calcic pyroxenes range from augite to ferroaugite (Ca30–40Mg40–17Fe15–45) and late-stage hedenbergite (Ca45 Mg5Fe50), and the pigeonites from intermediate to ferriferous types (Ca13Mg55–15Fe32–70). XMg numbers (Mg/(Mg + Fe)) of the calcic pyroxenes vary from 0.8 to 0.1, and of the calcium-poor pyroxenes (pigeonites) from 0.62 to 0.17. The chemical variation in the pyroxenes within individual samples is far greater than between the different samples. One sample contains an extremely wide range of pyroxenes which include some of the most ferriferous pigeonites ever recorded (Ca14Mg15 Fe71). Ti and Al contents are also highly varied, Ti:Al ionic ratios ranging from 1:15 to 1:2 with decreasing XMg. The augites have higher Ti and Al contents than pigeonites with corresponding XMg. The hedenbergites have erratic but generally low Ti contents, due to their late precipitation together with ulvospinel. The presence of such highly variable pyroxenes within individual samples and in some cases as single, complex grains makes the recognition of coexisting pyroxene pairs in such dolerites very difficult, but graphical pyroxene thermometers suggest a crystallization temperature range of 1100 to 850 °C.The range of pyroxene compositions in such dolerites is strongly influenced by the oxygen fugacity (fO2) of the liquid from which they derive. The primary Fe-Ti oxide phase in these Tasmanian dolerites is ulvospinel (now oxidized to ilmenite ‘oxidation-exsolution’ lamellae in titanomagnetite hosts) clearly demonstrating the originally low fO2 of the parental tholeiitic magma of the Mount Wellington sill.
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Thompson, Richard M., and Robert T. Downs. "Model pyroxenes I: Ideal pyroxene topologies." American Mineralogist 88, no. 4 (2003): 653–66. http://dx.doi.org/10.2138/am-2003-0419.

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Shatsky, V. S., A. L. Ragozin, Q. Wang, W. Su, A. A. Ilyin, and M. V. Kolesnichenko. "FEATURES OF THE STRUCTURE AND EVOLUTION OF THE LOWER PARTS OF THE CONTINENTAL CRUST OF THE YAKUTIAN DIAMONDIFEROUS PROVINCE IN THE AREA OF THE UPPER-MUNA KIMBERLITE FIELD." Доклады Российской академии наук. Науки о Земле 508, no. 2 (2023): 173–84. http://dx.doi.org/10.31857/s2686739722602393.

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Upper Muna kimberlite field) showed that the crust at different levels is composed of pyroxene, garnet-pyroxene crystalline schists and garnet-pyroxene gneisses. Exsolution textures in pyroxenes and amphiboles, granat rims around grains of ilmenite and pyroxenes indicate that the mineral associations of crystalline schists were formed during cooling at constant pressure. Р–Т equilibrium parameters indicate that garnet-pyroxene crystalline schists are present in the middle crust (P = 7–8 kbar), while garnet-pyroxene gneisses can be considered as rocks of the lower crust (P = 9–10.1 kbar). For the first time, sodalite was found in xenoliths of crystalline schists, which indicates the presence of brines with a high concentration of NaCl at the final stages of rock cooling. The determination of the U–Pb age of zircons testifies to the Neoarchean (2.7 Ma) tectono-thermal event, accompanied by the melting of the crust. In the garnet–pyroxene gneisses, the 1.9 stage is weakly manifistated. The obtained data confirm the earlier conclusion about the vertical and lateral heterogeneity of the crust of the Yakutsk diamondiferous province and the absence of dependence between the degree of crust reworking and spatial location relative to the main collision zones of the Siberian craton.
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Morel, S. W. "Petrology and geothermometry of the Little Michiru Complex, Malawi." Mineralogical Magazine 53, no. 371 (1989): 285–91. http://dx.doi.org/10.1180/minmag.1989.053.371.02.

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AbstractThe Little Michiru complex is a composite intrusion of pyroxenite and pyroxene syenite which is located at the boundary between amphibolite and granulite facies gneisses in the Shire rift valley. Pyroxene and feldspar chemistry shows that the intrusion consolidated from two magmatic fractions, one a pyroxenite cumulate that equilibrated at 870–1000 °C, the other a partly anatectic pyroxene syenite magma which metasomatized the surrounding gneisses during granulite-facies metamorphism and equilibrated at a temperature of 730–830 °C at 7 kbar.
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Giustetto, Roberto, Giacomo Chiari, and Roberto Compagnoni. "An easy non-invasive X-ray diffraction method to determine the composition of Na-pyroxenes from high-density `greenstone' implements." Acta Crystallographica Section A Foundations of Crystallography 64, no. 1 (2007): 161–68. http://dx.doi.org/10.1107/s0108767307062691.

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A large number of polished stone implements from Palaeolithic to Bronze Age sites of Northern Italy and Southern France are made of high-pressure (HP) metamorphic rocks (eclogite and related rocks), mainly consisting of Na-pyroxene (jadeite to omphacite) from the metamorphic belt of the Western Alps. The standard archaeometric study of prehistoric stone implements follows a procedure that is invasive, expensive and time-consuming. Since Na-pyroxenes may show a large compositional range, a thorough study of the variations affecting thedhklvalues, obtained by X-ray diffraction, of three selected reflections as a function of different chemical composition was carried out, in order to determine the chemistry of Na-pyroxene isomorphic mixtures and roughly evaluate their relative amounts. These reflections (\bar221, 310, 002) are sharp, intense and sensitive to the variation of pyroxene chemical composition. Using suchdhklvalues measured on pyroxenes of known chemistry, a Ca-pyroxene(Di)–jadeite(Jd)–aegirine(Ae) compositional diagram was constructed, from which the composition of an unknown pyroxene can be estimated within an error of about 5%. When the size of the object is relatively small and a flat polished surface is present, the proposed analytical procedure becomes totally non-invasive. The data obtained shed light on the provenance sources of such implements and the prehistoric trade routes.
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Duggan, M. B. "Zirconium-rich Sodic Pyroxenes in Felsic Volcanics from the Warrumbungle Volcano, Central New South Wales, Australia." Mineralogical Magazine 52, no. 367 (1988): 491–96. http://dx.doi.org/10.1180/minmag.1988.052.367.07.

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AbstractSoda-rich pyroxenes in felsic rocks from the Warrumbungle Volcano, central New South Wales, contain up to 14.5 wt. % ZrO2, which is more than double the previously reported maximum ZrO2 in pyroxene. Zr is believed to enter aegirine as the component Na(Fe2+,Mn,Mg)0.5Zr0.5Si2O6 via the coupled substitution: (Fe2+,Mn,Mg)VI+ZrVI = 2(Fe3+)VI. This component exceeds 50 mol. % in some analyses.Pronounced pyroxene Zr-enrichment is restricted to rocks in which sodic amphibole is the major ferromagnesian mineral, with pyroxene only a minor late-stage phase. The Zr-rich pyroxenes resulted from a combination of host lava peralkalinity, low oxygen fugacity, rapid disequilibrium crystallization and low mobility of the Zr ion. These factors collectively led to the development of interstitial Zr-enriched microdomains in the felsic hosts during their final stages of crystallization.
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Haslam, H. W. "Pyroxenes and coexisting minerals in the Cheviot granite." Mineralogical Magazine 50, no. 358 (1986): 671–74. http://dx.doi.org/10.1180/minmag.1986.050.358.13.

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AbstractOrthopyroxene and clinopyroxene, with biotite, are widespread in the high-level Cheviot granite, while amphibole is rare. The pyroxene compositions are very close to (Mg,Fe)2Si2O6 and Ca(Mg,Fe)Si2O6. Biotite compositions, with low Si and Al, are characteristic of biotites coexisting with pyroxenes. Geothermometric estimates based on oxide and pyroxene compositions show that present mineral compositions result from post-consolidation equilibration.
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Maruyama, S., J. G. Liou, and Y. Sasakura. "Low-temperature recrystallization of Franciscan greywackes from Pacheco Pass, California." Mineralogical Magazine 49, no. 352 (1985): 345–55. http://dx.doi.org/10.1180/minmag.1985.049.352.05.

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AbstractLow-temperature metamorphism of the Franciscan complex at Pacheco Pass occurs at P-T conditions near the so-called jadeite isograd. Along Highway 152 in the Diablo Range, from west to east, four distinct prograde metamorphic zones are defined: (I) albite-quartz zone, (II) albite-rich, albite-quartz-clinopyroxene assemblage, (III) clinopyroxene-rich, albite-quartz-clinopyroxene assemblage, and (IV) clinopyroxene zone. Metamorphic pyroxenes are restricted to zones II, III, and IV in metagreywackes, but metabasites contain augite-rich pyroxenes even in zone I. With increasing grade, the compositions of pyroxene in metagreywackes change in XJd from nearly 100 in zone II to about 60 in zone III. The diopside component has little effect on the XJd of pyroxene. The apparent change of XJd reflects differences in pressure and temperature rather than in bulk rock composition. In metagreywackes, at the onset of zone II, albite breaks down to form Jd100 according to the reaction Ab = Jd+Qz. With increasing grade, this reaction leads to less jadeitic pyroxene. From zones II to III, a continuous reaction is delineated: Qz+2 pyroxenes (Jd80Ac15Aug5)=pyroxene (Jd60Ac30Aug10) + Ab.The metamorphic temperatures are estimated to be about 170°C in zones I and II, and about 230°C in zones II and III. The temperature variation recorded in a single rock is probably less than 30°C The pressure estimate depends on the choice of experimental data for the jadeite-albite-quartz curve; it ranges from 4.5 to 8 kbar. A gently folded thermal structure of the Cretaceous subduction zone metamorphism is postulated for this area.
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Hall, R. P., D. J. Hughes, and C. R. L. Friend. "Complex sequential pyroxene growth in tholeiitic hypabyssal rocks from southern West Greenland." Mineralogical Magazine 50, no. 357 (1986): 491–502. http://dx.doi.org/10.1180/minmag.1986.050.357.12.

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AbstractChemically complex pyroxenes which occur in early Proterozoic tholeiitic dolerite dykes in southern West Greenland have been investigated using back-scattered electron (BSE) imagery, X-ray mapping and electron microprobe analysis. A wide variety of compositions occur within individual pyroxene grains in these rocks. They can be explained by simultaneous nucleation of different pyroxenes, the evolution of domains around these nucleii as a response to differential chemical gradients and the sequential precipitation of different pyroxenes at progressively lower temperatures. As an example, the individual grains in one dyke sample contain domains of bronzite, hypersthene, magnesium pigeonite, augite, and subcalcic augite. Olivine in this sample varies in composition from Fo70to Fo33, although individual grains are only weakly zoned. The wide variation in pyroxene and olivine compositions suggests ranges of crystallization temperatures fromc.1250° to as low as 825°C. Such compositionally variable pyroxenes are possibly characteristic of hypabyssal tholeiitic rocks.
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Bradley, J. P. "Physical and Mineralogical Properties of Anhydrous Interplanetary Dust Particles in the Analytical Electron Microscope." International Astronomical Union Colloquium 126 (1991): 63–70. http://dx.doi.org/10.1017/s0252921100066495.

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AbstractThe fine grained mineralogy and petrography of anhydrous “pyroxene” and “olivine” classes of chondritic interplanetary dust have been investigated by numerous electron microscopic studies. The “pyroxene” interplanetary dust particles (IDPs) are porous, unequilibrated assemblages of mineral grains, metal, glass, and carbonaceous material. They contain enstatite whiskers, FeNi carbides, and high-Mn olivines and pyroxenes, all of which are likely to be well preserved products of nebular gas reactions. Solar flare tracks are prominent in most “pyroxene” IDPs, indicating that they were not strongly heated during atmospheric entry. The “olivine” IDPs are coarse grained, equilibrated mineral assemblages that have probably experienced strong heating. Since most “olivine” IDPs do not contain tracks, it is possible that this heating occurred during atmospheric entry.
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Dissertations / Theses on the topic "Pyroxene"

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Folco, Luigi. "Pyroxene thermometry in chondritic meteorites." Thesis, Open University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389315.

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Davis, Jimmy Allen. "FREQUENCY DISTRIBUTION OF PYROXENE TYPES AND A METHOD TO SEPARATE THE COMPOSITION OF MULTIPLE PYROXENES IN A SAMPLE." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3145.

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Determining mafic mineral composition of asteroid bodies is a topic reviewed by M.J. Gaffey et al. (2002). The iterative procedure discussed can be implemented as an algorithm, and such efforts revealed weaknesses that are examined in this work. We seek to illustrate the limits of this method and graphically determine its predictions. There are boundaries in the formulae given where the equations break down. In ranges where mafic mixtures are predicted, a method is illustrated that allows a decoupling of these mixtures into the constituents.<br>M.S.<br>Department of Physics<br>Sciences<br>Physics MS
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Ohi, Shugo. "High temperature orthorhombic pyroxene --Phase transition between low and high temperature orthorhombic pyroxene and phase relation in enstatite-diopside system at high temperature--." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124430.

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Bouquain, Sébastien. "Cristallochimie du pyroxene dans les komatiites et las basaltes lunaires." Grenoble 1, 2008. http://www.theses.fr/2008GRE10036.

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Soustelle, Vincent. "Interactions entre déformation et percolation de magma ou de fluide dans le manteau à l'aplomb des zones de subduction." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20151/document.

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Ce travail apporte de nouvelles contraintes sur les interactions entre déformation et processus d'hydratation et de percolation de magma ou de fluides et leurs implications sur les propriétés sismiques dans le coin mantellique. Il se base sur l'analyse de péridotites à spinelle provenant du massif de Ronda (Espagne) et deux séries de xénolites issues de zones de subduction actives (Kamchatka, Papouasie-Nouvelle-Guinée). L'étude structurale, pétrologique et géochimique de ces échantillons montrent qu'ils ont subi une percolation réactive de magma ou de fluide synchrone d'une déformation de haute température basse contrainte cohérente avec les condition PT de la base de la lithosphère ou de l'asthénosphère. Cette percolation réactive est responsable d'un enrichissement en pyroxènes localisés dans des bandes parallèles aux structures de déformation. Cet enrichissement est associé à la décroissance et à la désorientation des cristaux d'olivine. Le système de glissement dominant dans l'olivine est {0kl}[100], cela implique que la direction de polarisation rapide des ondes S dans la partie supérieure du coin mantellique est parallèle à la direction d'écoulement du manteau. L'enrichissement en pyroxène associé à une décroissance de l'intensité des OPR de l'olivine a pour conséquence une baisse non négligeable de l'anisotropie qui peut induire jusqu'à 33% d'erreur sur l'interprétation de la couche anisotrope. Un enrichissement en orthopyroxène peut entraîner une baisse du rapport Vp/Vs, mais ne peut expliquer des Vp/Vs &lt;1,7 cartés dans certains avant-arcs. Cependant de telles valeurs peuvent être expliquées si l'anisotropie des péridotites du coin mantellique est prise en compte<br>This work provides new constraints on the interactions between deformation and hydration process and the percolation of melt or fluids, and their implications for seismic properties of the mantle wedge. It is based on the analysis of spinel peridotites from the massif of Ronda (Spain) and two xenolith suites from active subduction zones (Kamchatka, Papua New Guinea). The structural, petrological and geochemical of these samples show that they underwent a reactive percolation of melt or fluid, which was synchronous to a deformation event occuring under high temperature and low stress consistent with the PT conditions of the base of the lithosphere or in the asthenosphere. This reactive percolation is responsible for pyroxenes enrichment localized in bands parallel to the deformation structures. This enrichment is associated with the grain size recuction and the disorientation of the crystals of olivine. The dominant slip system in olivine is {0 kl}[100], which results in fast S-wave polarization parallel to the flow direction in the mantle. The enrichment in pyroxene, associated with a decrease in the intensity of the olivine crystal preferred orientations, results in a significant decrease of the anisotropy that may induce error on the interpretation of the anisotropic layer (up to 33%). The observed orthopyroxene enrichment also lowers the Vp/Vs ratio, but cannot explain Vp/Vs &lt; 1.7 mapped in some fore-arc mantles. Such low Vp/Vs ratios may however be explained by considering the intrinsic anisotropy of the peridotites, which is generally ignored in large-scale Vp/Vs ratio mapping of the mantle wedge
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Burness, Sara. "Pyroxene stability within kimberlite magma in the upper mantle : an experimental investigation." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96837.

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Thesis (MSc)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: Entrainment and assimilation of xenolithic material during kimberlite ascent is considered to be important in shaping the chemistry of the magma and fuelling magma ascent by driving CO2 exsolution. Previous, but as yet unpublished experimental work from Stellenbosch University has demonstrated that orthopyroxene has a key role in this. Orthopyroxene is a very rare xenocrystic constituent of kimberlite but makes up a considerable fraction of the entrained xenolithic material. The initial study used a natural kimberlite composition (ADF1) doped with a peridotite mineral suite (by weight); 88 % ADF1 5% olivine, 5% orthopyroxene and 2% garnet-spinel intergrowth as a starting composition. The subsequent high PT experiments (1100 to 1300°C and 2.0 to 3.5GPa) established that equilibrium orthopyroxene is stable at 1100°C above 2.5GPa, at 1200°C above 2.5GPa and at 1300°C between 2.0 and 3.5GPa. At lower pressures orthopyroxene is completely digested by the experimental melt by the reaction; Mg2Si2O6 (opx) = Mg2SiO4 (ol) + SiO2 (in liquid). In contrast, clinopyroxene is a common phase in kimberlite and often occurs as more than one generation of crystals. Xenocrystic clinopyroxene is dominated by diopside compositions. However, rare omphacite is sometimes also inherited from an eclogite source. The Omphacite, like orthopyroxene, displays textural evidence of severe disequilibrium and may also contribute to the evolution of kimberlitic melt. Thus, a second study produced experiments on the ADF1 kimberlite material at upper mantle PT conditions (1100 to 1300°C and 2.0 to 4.0GPa) as well as an omphacite doped starting material (ADF1+O). These experiments examine the behaviour of pyroxene in kimberlite magma including the influence this may have on magma buoyancy. Within this PT range omphacitic clinopyroxene breaks-down via complex multipart reactions. At 1100°C and 2.0GPa reaction textures around remnant omphacite suggest that omphacite melts incongruently in a complex reaction similar to: Omp + Melt = Ap + Cr-diop + SiO2-enriched Melt. At 1300°C omphacite melts completely and is perceived to produce peritectic Cr-diopside, calcium-rich olivine, carbonate in the melt as well as enrich the melt in SiO2. The melts produced by both the ADF1+O and ADF1 compositions at 1300°C and 4.0GPa are reduced in SiO2 content and have increased TiO2, Cr2O3, Al2O3, MnO, CaO, K2O and P2O5 compared to their respective starting compositions. However, significantly higher proportions of Ca, Na and Fe observed within the ADF1+O melt is a direct consequence of omphacite melting. The ADF1+O starting composition produced equilibrium orthopyroxene above 1100°C and 4.0GPa as well as at 1300°C above 2.0GPa. At lower pressure the orthopyroxene melts incongruently to form peritectic olivine and more silica-rich melt compositions. This digestion favours CO2 exsolution. The effect of orthopyroxene melting can be seen in the melt compositions produced by the peridotite doped starting material (ADF1+P) of the initial study. At 1300°C and 2.0GPa, ADF1+P produced a siliceous melt (37.0 wt.% SiO2) enriched in Al and alkalis compared to the starting ADF1+P composition. This behaviour is directly attributed to xenocrystic orthopyroxene melting at high temperature. In contrast, at the same PT the original kimberlite (ADF1) composition produces a melt with 28.9 wt.% SiO2 and high Ca and Mg contents. Overall, with an increase in pressure the melts become enriched in alkalis and Al2O3 as a direct result of xenocrystic pyroxene melting. In addition, increased pressure allows for a greater solubility of CO2 within the melt. This results in a lower SiO2 melt content and the increased stabilization of equilibrium silica-rich mineral phases (i.e. olivine and equilibrium orthopyroxene). Within the peridotite doped static system (unpublished) the mineral separates with an average crystal size of 115μm ±10μm were all effectively digested in less than 48hours. Similarly, the omphacite doped experiments consumed the 150μm (±10μm) xenocrysts in under 24 hours. Thus, it is suggested that xenocrystic pyroxene is unstable in these experimental kimberlitic melt compositions and is likely to be efficiently assimilated in less than 24 hours. These experimental melts most likely resemble those of natural systems under upper mantle PT conditions. Therefore, pyroxene melting increases the silica content of the melt which in turn drives CO2 exsolution and ascent.<br>AFRIKAANSE OPSOMMING: Meevoering en assimilasie van xenolitiese materiaal gedurenende kimberliet bestyging is beskou as belangrik in verband met die vorming van die chemie van die magma, en bevorder magma bestyging deur die aandrywing van CO2 ontmenging. Vorige, maar ongepubliseerde eksperimentele werk vanaf Stellenbosch Universiteit het gedemonstreer dat ortopirokseen ‘n sleutelrol hierin het, omrede ortopirokseen ‘n baie skaars xenokristiese bestanddeel van kimberliet is maar ‘n aansienlike fraksie van die meevoerde xenolitiese materiaal moet opmaak. Hierdie studie het ‘n natuurlike primere kimberliet komposisie (ADFI) gedoop met ‘n peridotiet mineraal reeks (per gewig); 88 % ADF1 5% olivien, 5% ortopirokseen en 2% granaat-spinel ingroeiing as begin komposisie gebruik. Die daaropvolgende hoë DT eksperimente (1100 tot 1300°C en 2.0 tot 3.5GPa) het vasgestel dat ewewigsortopirokseen stabiel is teen 1100°C bo 2.5GPa, 1200°C bo 2.5GPa en teen 1300°C vanaf 2.0 tot 3.5Gpa. Teen laer druk word ortopirokseen geheel verteer deur die eksperimentele smelting volgens die reaksie Mg2Si2O6 (opx) = Mg2SiO4 (ol) + SiO2 (in vloeistof). In kontras hiermee is clinopirokseen algemeen in kiemberliet en kom dikwels voor as meer as een generasie se kristalle. Diopsiet komposisies domineer xenokristiese klinopirokseen. Seldsame omfasiet is tog somtyds ook geërf vanaf ‘n eklogiet bron. Die omfasiet, soos ortopirokseen, vertoon teksturuele bewys van ernstige disekwilibrium en mag ook bydra tot die evolusie van kimberlitiese smelt. Dus was daar addisionele eksperimente uitgevoer op die ADF1 kimberliet material teen hoër mantel DT kondisies (1100 tot 1300°C en 2.0 tot 4.0GPa), asook ‘n begin materiaal gedoop met omfasiet (ADF1+O). Hierdie eksperimente ondersoek die gedrag van pirokseen in kiemberliet magma, asook die invloed wat dit sal hê op die dryfvermoë van die magma. Binne hierdie DT reeks breek omfasitiese klinopirokseen af via komplekse multideel reaksie prosesse. Teen 1100°C en 2.0Gpa stel reaksie teksture rondom die oorblywende omfasiet voor dat omfasiet ongelykvormig smelt deur ‘n komplekse reaksie soortgelyk aan: Omp + Smelt = Ap + Cr-diop + SiO2-verrykde Smelt. Teen 1300°C smelt omfasiet volkome en is waargeneem om peritektiese Cr-diopsiet, kalsiumryke olivien en kalsiet te produseer, sowel as dat dit die smelt verryk in SiO2. Die smeltings geprodiseer deur die ADF1+O en ADF1 massa komposisies teen 1300°C en 4.0GPa is verlaag in SiO2 inhoud en bevat verhoogde TiO2, Cr2O3, Al2O3, MnO, CaO, K2O en P2O5 in vergelyking met die onderskeie begin komposisies. Aansienlike hoër proporsies van Ca, Na en Fe is egter waargeneem in die ADF1+O smelt en is ‘n direkte gevolg van die smelting van omfasiet. Die ADF1+O begin samestelling het ewewigsortopirokseen bo 1100°C en 4.0Gpa geproduseer en massa teen 1300°C en 2.0 tot 4.0GPa. Teen laer druk smelt hierdie pirokseen inkongruent om peritektiese olivien en meer silika-ryke smelt samestellings te vorm, en ontmeng CO2. Die effek van ortopirokseen smelting kan aanskou word in die smelt samestellings wat produseer is deur die begin materiaal wat gedoop is in peridotiet (ADF1+P), in die oorspronklike studie. Teen 1300°C en 2.0GPa het ADF1+P ‘n silikahoudende smelt (37.0 wt.% SiO2) produseer wat verryk is in Al en alkalies in vergelyking met die ADF1+P massa samestelling. Hierdie gedrag is direk toegeskryf aan die xenokristiese ortopirokseen wat smelt teen hoë temperatuur. In kontras hiermee, teen dieselfde DT kondisies produseer die oorspronklike kiemberliet (ADF1) massa ‘n smelt met 28.86 gewigspersentasie SiO2 en hoë Ca en Mg inhoud. In die algeheel word die smeltings verryk in alkalies en Al2O3 teen verhoogde druk as ‘n derekte gevolg van xenokristiese pirokseen smelting. Verder laat verhoogde druk toe vir hoër oplosbaarheid van CO2 in die smelt, wat lei tot laer SiO2 inhoud en ‘n toename in stabilisering van ewewigs silika-ryke mineraal fases (dws. olivien en ewewigsortopirokseen). In die peridotiet gedoopde statiese sisteem (ongepubliseerd), was die mineraal skeiding met ‘n gemiddelde kristal grootte van 115μm ±10μm almal effektief verteer in minder as 48 ure. Soortgelyk hieraan het die omfasiet gedoopde eksperimente die 150μm (±10μm) sade onder 24 ure verteer. Dus stel dit voor dat xenokristiese pirokseen in naatuurlike sisteme onstabiel is in kiemberlietiese smelt samestellings en sal waarskynlik geassimileer wees in miner as 24 ure en ‘n meer silica-ryke kiemberlietiese smelt samestelling produseer terwyl dit CO2, ontmenging en bestyging aandryf.
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Shackleton, Natalie Jean. "The role of complexing agents in the flotation of pentlandite-pyroxene mixtures." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/10976.

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Bibliography: leaves 137-146.<br>This study examines the role complexing agents play in pentlandite-pyroxene flotation and focuses on the surface chemistry and interaction between valuable and gangue minerals as well as the interaction of complexing agents and reagents (xanthate, copper sulphate) in the system at pH 9. Microflotation, zeta potential measurements, ToF-SIMS analyses (time of flight secondary ion mass spectrometry) and X-ray photoelectron spectroscopy (XPS) were used as tools in determining the extent of surface alteration.
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Meado, Andrea. "Crystallization History of Gabbroic Shergottite NWA 6963 as Revealed by Pyroxene Zoning." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2191.

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Northwest Africa 6963 (NWA 6963) is an intriguing new coarse grained, gabbroic Martian meteorite that further extends our sample collection both compositionally and texturally. Basaltic shergottites offer insight to volcanic igneous processes on the Martian surface and can be used to predict subsurface conditions. Gabbroic shergottite NWA 6963 provides direct petrologic evidence of intrusive igneous conditions within the Martian crust that extrusive meteorite samples cannot match. NWA 6963 is composed of coarse grained clinopyroxenes and maskelynite with sub-ophitic textures supporting its intrusive origin. Zoning textures in clinopyroxenes, augite and pigeonite, are analyzed to determine the crystallization history of NWA 6963. Compositional zoning profiles reveal pyroxenes with augite or pigeonite cores mantled by Fe-rich pigeonite rims. In NWA 6963 the pyroxenes cores are in equilibrium with one another, but cores are not in equilibrium with respective Fe-rich pigeonite rims in the same grain. This study suggests reasons for complex pyroxene textures and compositions observed in NWA 6963 are due to magma undercooling and possibly volatile expulsion during two distinct stages of crystallization history.
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Malysiak, Vratislav. "Pentlandite-pyroxene and pentlandite-feldspar interactions and their effect on separation by flotation." Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5291.

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Bibliography: leaves 139-146.<br>The present study has focused on exploring the extent to which metal ion activation occurs and influences flotation and how this can be managed so as to increase the separation of pentlandite from pyroxene and feldspar. The aim was to minimise the percentage pyroxene and feldspar reporting to the concentrate and simultaneously maximise the pentlandite recovery. The possible chemical reactions taking place on surfaces of synthetic pentlandite, natural pyroxene and feldspar were investigated at pH 4, 6 and 9 in di-sodium tetra borate solution and in synthetic process water in the case of zeta potential determinations, microflotation and ToF-SIMS (time of flight secondary ion mass spectrometry) analyses and in synthetic process water in the case of batch flotation tests.
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Pens, Maria. "Etude expérimentale de l’altération hydrothermale des roches ultrabasiques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1107/document.

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Les péridotites, roches du manteau terrestre, sont instables en présence d'eau et peuvent se transformer en un minéral hydraté la serpentine, qui a la capacité remarquable de générer de l'hydrogène H2; cette réaction s'appelle la serpentinisation. Au niveau des dorsales médio-océaniques, la circulation d'eau dans ces roches conduit à la formation de larges systèmes hydrothermaux. Ils montrent différentes conditions de température et de pH des fluides, bien qu'ils conduisent tous à la formation abiotique d'H2, de méthane CH4 et possiblement d'autres hydrocarbures légers.Cette thèse est dédiée à l'étude du rôle de la composition chimique du fluide hydrothermal sur la cinétique et les mécanismes de serpentinisation des roches ultrabasiques à différentes conditions de P-T. L'interaction entre l'olivine et/ou l'orthopyroxène a été analysée avec une solution aqueuse simulant une eau de mer enrichie en aluminium et/ou en ions bicarbonates, à différents pH. Une première série d'expériences a été réalisée à 200, 340 °C et 200 MPa en lp-DAC à l'ESRF en France. Elle a permis de quantifier les paramètres cinétiques de réaction, de déterminer un effet opposé de l'aluminium sur la cinétique de ces deux minéraux et l'accélération de la réaction en conditions alcalins. Autres expériences ont été réalisée à Pamb et 80 °C en flacons de verre. Elles ont conduit, pour la première fois, à la formation de serpentine ainsi qu'à la formation d'H2 et de CH4. Ces résultats montrent qu'une chimie plus complexe du fluide hydrothermal peut avoir un impact majeur sur la cinétique de la serpentinisation pour l'accélérer et la rendre plus accessible à une échelle de temps industrielle<br>Peridotites, Earth's mantle rocks, are unstable in the presence of water and can be transformed into a hydrated mineral, serpentine, which has the remarkable ability to generate hydrogen H2; this reaction is called serpentinization. At the mid-ocean ridges, the circulation of water in these rocks leads to the formation of large hydrothermal systems. They show great variability of temperature and fluids’pH conditions, although they all lead to the abiotic formation of H2, methane CH4 and eventually other light hydrocarbons. This PhD thesis is dedicated to the study of the chemical composition role of the hydrothermal fluid on the kinetics and mechanisms of serpentinization of ultramafic rocks to different conditions of P-T. The interaction between olivine and/or orthopyroxene was analyzed with an aqueous solution to simulate sea water which is rich in aluminum and/or bicarbonate ions, with different pH values. A first series of experiments was carried out at 200, 340 °C and 200 MPa in lp-DAC at the ESRF in France. It was used to quantify the kinetic parameters of the reaction, to determine an opposite effect of aluminum on the kinetics these two minerals and the acceleration of the reaction under alkaline conditions. Other experiments were performed in glass bottles at Pamb and 80 °C. They led, for the first time, to the formation of serpentine, as well as to the formation of H2 and CH4. These results show that the slightly more complex chemistry of the hydrothermal fluid can have a major impact on the kinetics of serpentinization to speed and make it more accessible to industrial time scale
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Books on the topic "Pyroxene"

1

Khomenko, V. M. Porodoobrazui͡u︡shchie pirokseny: Opticheskie spektry, okraska i pleokhroizm. Nauk. dumka, 1987.

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Koga, Kenneth Tadao. Kinetic processes of mantle minerals. Massachusetts Institute of Technology, Woods Hole Oceanographic Institution, Joint Program in Oceanography/Applied Ocean Science and Engineering, 2000.

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Yanhong, Zhang, and United States. National Aeronautics and Space Administration., eds. Pyroxene structures, cathodoluminescence and the thermal history of the enstatite chondrites. National Aeronautics and Space Administration, 1996.

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Malysiak, Vratislav. Pentlandite-pyroxene and pentlandite-feldspar interactions and their effect on separation by flotation. University of Cape Town, Faculty of Chemical Engineering and Built Environment, 2003.

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El-Jaer, A. M. Luminescence spectroscopy of transition metal ions in pyroxenes. UMIST, 1997.

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Joyner, Louise. The geochemistry and crystallisation history of pyroxenes from hypabassal basic igneous rocks. University of Portsmouth, Dept. of Geology, 1993.

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Mungall, James E. Geochemistry of carbonatite and alkali pyroxenite, Bancroft terrane, Grenville province, Ontario. UMI Dissertation Services, 1998.

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Foose, M. P. Setting of a magmatic sulfide occurrence in a dismembered ophiolite, southwestern Oregon. G.P.O., 1986.

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Drake, Avery Ala. The Soldiers Delight ultramafite in the Maryland Piedmont. U.S. G.P.O., 1994.

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L, Jolliff Bradley, Haskin Larry A, and United States. National Aeronautics and Space Administration., eds. Raman spectroscopy as a method for mineral identification on lunar robotic exploration missions. National Aeronautics and Space Administration, 1995.

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Book chapters on the topic "Pyroxene"

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Liebermann, Robert C. "Elasticity of pyroxene-garnet and pyroxene-ilmenite phase transformations in germanates." In Elastic Properties and Equations of State. American Geophysical Union, 1988. http://dx.doi.org/10.1029/sp026p0321.

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Cherniak, D. J., and A. Dimanov. "14. Diffusion in Pyroxene, Mica and Amphibole." In Diffusion in Minerals and Melts, edited by Youxue Zahng and Daniele J. Cherniak. De Gruyter, 2010. http://dx.doi.org/10.1515/9781501508394-015.

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Weiss, S. "Nucleation and Growth of Pyroxene in the Hypersthene Diorites." In Equilibrium and Kinetics in Contact Metamorphism. Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76145-4_5.

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Verma, H. C., V. C. Tewari, B. S. Paliwal, and R. P. Tripathi. "Preferential occupation of pyroxene sites by iron in diogenite meteorites." In ICAME 2007. Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78697-9_146.

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Akaogi, Masaki. "Phase Transitions of Pyroxene and Garnet, and Post-spinel Transition Forming Perovskite." In High-Pressure Silicates and Oxides. Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6363-6_6.

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Koike, Chiyoe, and Akira Tsuchiyama. "The Infrared Spectra of Synthesized Amorphous Silicates with Compositions of Olivine and Pyroxene." In Origin and Evolution of Interplanetary Dust. Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3640-2_19.

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Papike, James J. "Chapter 7. COMPARATIVE PLANETARY MINERALOGY: CHEMISTRY OF MELT-DERIYED PYROXENE, FELDSPAR, AND OLIVINE." In Planetary Materials, edited by James J. Papike. De Gruyter, 1998. http://dx.doi.org/10.1515/9781501508806-022.

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Akaogi, Masaki, Alexandra Navrotsky, Takehiko Yagii, and Syun-iti Akimoto. "Pyroxene-garnet transformation: Thermochemistry and elasticity of garnet solid solutions, and application to a pyrolite mantle." In High‐Pressure Research in Mineral Physics: A Volume in Honor of Syun‐iti Akimoto. American Geophysical Union, 1987. http://dx.doi.org/10.1029/gm039p0251.

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Zhang, Ronghua, Shumin Hu, and Xuetong Zhang. "Anhydrite-pyrite-magnetite-pyroxene-type deposits in volcanic basins of a Mesozoic continent, Yangtze River Valley, China." In Mineral Deposit Research: Meeting the Global Challenge. Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_183.

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Ghose, Naresh Chandra, Nilanjan Chatterjee, and Fareeduddin. "Pyroxenite." In A Petrographic Atlas of Ophiolite. Springer India, 2013. http://dx.doi.org/10.1007/978-81-322-1569-1_9.

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Conference papers on the topic "Pyroxene"

1

Kvasnytsia, I. "Surface microtopography of pyroxene crystals." In Geoinformatics. European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.20215521086.

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Oliveira, Antonio, Helena Martins, and Helena Sant Ovaia. "PYROXENE MINERAL CHEMISTRY OF A MICROGABBRO DYKE FROM VILA NOVA DE FOZ COA (NORTHERN PORTUGAL)." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/1.1/s01.16.

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This work is a mineral chemistry study of the pyroxene crystals composing a microgabbro dyke found in the Vila Nova de Foz Coa (VNFC) region of northern Portugal. Several pyroxene geothermometers and geobarometers have also been employed to infer the likeliest thermodynamic conditions of crystallization. Following the IMA 1988 report for the nomenclature of pyroxene minerals, the VNFC microgabbro is rich in Ca-Mg-Fe species. The studied clinopyroxenes are aluminian, chromian, and/or ferroan diopside and augite, whereas the existing orthopyroxenes are ferroan enstatite. The pyroxene compositional data suggest that the analyzed clinopyroxenes were generated from an OIB-like alkaline melt, at low to intermediate pressures, and high fO2 conditions, associated with a non-orogenic and presumably riftrelated setting. Furthermore, the clinopyroxene grains of the VNFC microgabbro probably crystallized under pressure conditions ranging from 5 to 13 kbar and temperatures between 1130 to 1187�C. The variations concerning the pressure estimates may be related to the isothermal decompression phenomenon, typically associated with dyke-type intrusions. Based on these estimates and assuming crustal densities of 2700 to 2890 kg/m3, the likeliest depths at which clinopyroxene formed vary between 49 to 16 km, with most grains crystallized at depths ranging from 49 to 40 km.
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Bulegenov, Kanat, Sayat Rais, and Daulet Muratkhanov. "GEOLOGY OF PERMIAN GRANITES OF THE KARATAU-NARYN ZONE AND THEIR PROSPECTIVE FOR RARE METALS (SOUTH KAZAKHSTAN)." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/1.1/s01.07.

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The studied intrusive massif is an ellipse elongated in the sublatitudinal direction. Only the eastern part, 2.2x4 km in size, is exposed on the earth surface. Under the sediments, the intrusion was traced by boreholes and aeromagnetic survey. The intrusion is a sheetlike body of a fractured nature, inclined to the southwest. A zone of marmorized limestones, as well as tremolite and wolastonite hornfelses, formed at the contact with the intrusion. Among the intrusive rocks that make up the massif, three successive igneous phases are distinguished. The first phase is represented by pyroxenites, biotite pyroxenites, alaskites, hornblendites, pyroxene-hornblende shonkinites and pseudoleucite facies, in which mesocratic and melanocratic syenites are distinguished. The rocks of the second phase are pyroxene-biotite and hornblend-biotite-pyroxene shonkinites, monzonites, syenites, which have gradual transitions. The rocks of the third intrusive phase are represented by biotite-pyroxene-hornblend syenites. A characteristic feature of syenites is the abundance of xenoliths of rocks of the first and second phases and marbles. The main rock-forming minerals of these rocks are orthoclase, hornblend, diopside-augite, minor ones: biotite, acidic or intermediate plagioclase, nepheline. The rocks of the intrusion are enriched in zinc, yttrium, copper, tin, molybdenum, vanadium, and lead. In addition, they contain increased amounts of cobalt and silver. Intrusions have been studied and their prospects for rare metals and rare earth elements have been evaluated.
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Befus, Kenneth, and Suyu Fu. "RAMAN BAROMETRY FOR MAGMATIC SYSTEMS USING FELDSPAR AND PYROXENE." In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-286513.

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Alba-Aldave, L. A., K. E. Cervantes-de la Cruz, R. Y. Sato-Berru, et al. "Ca-poor Pyroxene Raman Characteristics in H Ordinary Chondrites." In MICRO-RAMAN SPECTROSCOPY AND LUMINESCENCE STUDIES IN THE EARTH AND PLANETARY SCIENCES: Proceedings of the International Conference Spectroscopy 2009. AIP, 2009. http://dx.doi.org/10.1063/1.3222884.

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Zolensky, Michael, and Ruth Barrett. "Olivine and pyroxene compositions of chondritic interplanetary dust particles." In Analysis of interplanetary dust: NASA/LPI workshop. AIP, 1994. http://dx.doi.org/10.1063/1.46526.

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Stephan, Katrin, Ralf Jaumann, Maria C. De Sanctis, et al. "Spin-forbidden pyroxene absorptions in the vir-spectra of 4Vesta." In 2015 7th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS). IEEE, 2015. http://dx.doi.org/10.1109/whispers.2015.8075469.

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Majumdar, Ankan, Suchit Purohit, and Urs Mall. "Machine learning-based mapping of pyroxene on global lunar surface." In 2023 International Conference on Machine Intelligence for GeoAnalytics and Remote Sensing (MIGARS). IEEE, 2023. http://dx.doi.org/10.1109/migars57353.2023.10064622.

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Makarewicz, Joseph S., and Heather D. Makarewicz. "Spectral mixture decomposition using principal component analysis applied to pyroxene mixtures." In 2013 5th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS). IEEE, 2013. http://dx.doi.org/10.1109/whispers.2013.8080604.

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Moine, Bertrand, Nathalie Bolfan-Casanova, Ioana-Bogdana Radu, et al. "First inference of molecular Hydrogen in mantle pyroxene and isotopic consequences." In Goldschmidt2021. European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.4515.

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Reports on the topic "Pyroxene"

1

Jackson, L. E., and P. Rotheisler. Surficial geology, Pyroxene Mountain, Yukon Territory. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2002. http://dx.doi.org/10.4095/213870.

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Mohammadi, N., D. Corrigan, A. A. Sappin, and N. Rayner. Evidence for a Neoarchean to earliest-Paleoproterozoic mantle metasomatic event prior to formation of the Mesoproterozoic-age Strange Lake REE deposit, Newfoundland and Labrador, and Quebec, Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330866.

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A complete suite of bulk major- and trace-elements measurements combined with macroscopic/microscopic observations and mineralogy guided by scanning electron microscope-energy dispersive spectrometry (SEM-EDS) analyses were applied on Nekuashu (2.55 Ga) and Pelland (2.32 Ga) intrusions in northern Canada, near the Strange Lake rare earth elements (REE) deposit, to evaluate their magmatic evolution and possible relations to the Mesoproterozoic Strange Lake Peralkaline Complex (SLPC). These Neoarchean to earliest-Paleoproterozoic intrusions, part of the Core Zone in southeastern Churchill Province, comprise mainly hypersolvus suites, including hornblendite, gabbro, monzogabbro/monzodiorite, monzonite, syenite/augite-syenite, granodiorite, and mafic diabase/dyke. However, the linkage of the suites and their petrogenesis are poorly understood. Geochemical evidence suggests a combination of 'intra-crustal multi-stage differentiation', mainly controlled by fractional crystallization (to generate mafic to felsic suites), and 'accumulation' (to form hornblendite suite) was involved in the evolution history of this system. Our model proposes that hornblendite and mafic to felsic intrusive rocks of both intrusions share a similar basaltic parent magma, generated from melting of a hydrous metasomatized mantle source that triggered an initial REE and incompatible element enrichment that prepared the ground for the subsequent enrichment in the SLPC. Geochemical signature of the hornblendite suite is consistent with a cumulate origin and its formation during the early stages of the magma evolution, however, the remaining suites were mainly controlled by 'continued fractional crystallization' processes, producing more evolved suites: gabbronorite/hornblende-gabbro ? monzogabbro/monzodiorite ? monzonite ? syenite/augite-syenite. In this proposed model, the hydrous mantle-derived basaltic magma was partly solidified to form the mafic suites (gabbronorite/hornblende-gabbro) by early-stage plagioclase-pyroxene-amphibole fractionation in the deep crust while settling of the early crystallized hornblende (+pyroxene) led to the formation of the hornblendite cumulates. The subsequent fractionation of plagioclase, pyroxene, and amphibole from the residual melt produced the more intermediate suites of monzogabbro/monzodiorite. The evolved magma ascended upward into the shallow crust to form monzonite by K-feldspar fractionation. The residual melt then intruded at shallower depth to form syenite/augite-syenite with abundant microcline crystals. The granodiorite suite was probably generated from lower crustal melts associated with the mafic end members. Later mafic diabase/dykes were likely generated by further partial melting of the same source at depth that were injected into the other suites.
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