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Showing 1 to 20 of 27 for “"enstatite"”.
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Exploring the Enstatite Chondrites: Modal Abundances, Metamorphic History, and Volatile Challenges
… thermal histories, and volatile inventories of enstatite chondrites (ECs). A diverse set of ECs is analyzed to capture the broad variability within this meteorite class. Chapter 1 presents a comparative analysis of mineral abundances using automated point counting, X-ray diffraction analysis, …
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Paleomagnetic Investigation of Enstatite Chondrite Chondrules: Implications for the Solar Nebula
… on two dusty olivine chondrules from high iron enstatite chondrites with variable kamacite grain sizes implied strong inner nebular field (∼1-2 AU) intensities of 185 ± 111 µT and 299 ± 247 µT. One new dusty olivine chondrule, containing exclusively submicron kamacite grains, suggested an inner …
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Major element diffusion in garnet and the exsolution of majoritic garnet from aluminous enstatite in Earth's Upper Mantle
Majorite is a high pressure polymorph of enstatite with the garnet structure. The amount of enstatite that can be dissolved in garnet as a majorite component increases significantly with pressure, and therefore, majoritic garnet is thought to be a major constituent of the Earth's transition zone. …
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Studies of clay minerals and their decomposition products
… 800 C. Hectorite gradually recrystallises to enstatite at temperatures above 700°C. At 900 C the crystalline structure of all three clay minerals had totally collapsed. Solid state reactions occurred above 900 C producing such phases as spinel, hematite, enstatite, cristobalite and mullite. …
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Aspects of the chemistry of some stony meteorites
… missing] Ten eucrites, four howardites, three enstatite achondrites, eight HL chondrites, the one known chassignite and a chondrite inclusion from the Cumberland Falls achondrite have been analysed for major, minor and some trace elements (viz. Fe, Mn, Ca, Cr, P, Si, Al, Mg, Na, K, Sr, Zr, Y, …
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Sound velocity study of natural orthopyroxenes with varying iron content
… moduli as a function of composition in the enstatite-orthoferrosilite system. For each sample and composition, the sound velocities are measured by Brillouin scattering in three orthogonal crystallographic planes. Inverting sound velocity data allows determination of the complete elastic …
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Hasandağ doğusu (Niğde) volkaniklerinin petrolojik modellemsi
… (55%), orthoclase (8%), and others (diopsite-1%, enstatite-ferrosilite (=hypersthene)-5%). Flow structure-III composed of quartz (26%), plagioclase-andesine (53%), orthoclase (10%), and others (diopsite-2%, enstatite-ferrosilite-7%, magnetite-1%). Opaques are mostly composed of magnetite, …
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An experimental approach to thermal and solar weathering of Mercury's crust
… the low-iron minerals anorthoclase feldspar, enstatite orthopyroxene, and diopside clinopyroxene. Our results indicate that sodium rich feldspars have the potential to contribute sodium to the exosphere, but in order to to produce potassium from the surface, more potassium rich felspars may be …
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Isotopic and Elemental Compositions of Stardust and Protosolar Dust Grains in Primitive Meteorites
… predict Mg-rich phases such as forsterite and enstatite to form. Although secondary alteration processes have probably modified the compositions of some presolar silicate grains in Acfer 094, the source of the Fe enrichments in most silicate grains is arguably primary. This work has led to the …
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NATURAL ANALOGUES OF PLANET MERCURY’S SURFACE: MINERALOGICAL AND SPECTROSCOPIC ASPECTS
… is dominated by Na-rich plagioclase, FeO-poor enstatite and forsterite, and Mg–Ca–Fe sulphides, suggesting that Mercury formed in the inner part of the protoplanetary disk from highly reduced precursor materials. However, the interpretation of Mercury’s spectral properties remains complex due …
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Selective Reduction of Laterite Ore
… was converted into olivine (forsterite) and enstatite at 600-800 °C. Olivine crystallised at temperatures above 810 °C. Ni-bearing phases after heat treatment at 800-850 °C were forsterite, enstatite, talc, iron silicate and monoxide. Upon heating to 1000 °C, talc was converted into pyroxene. …
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Developing Levitation Laser-Fused Glasses as Proxies for Lower Mantle Experiments: a Methodological Approach
… that accurately span the composition space from enstatite (MgSiO3) to forsterite (Mg2SiO4), as well as Fe-bearing enstatite ((Mg0.1Fe0.9)SiO3 and ((Mg0.95Fe0.05)(Si0.95Fe0.05)O3) with variable oxidation states. This study systematically tests and iterates upon glass synthesis methods using an …
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THE CONCENTRATION OF HYDROGEN IN INCOMPLETELY AND WHOLLY MELTED TERRESTRIAL BUILDING BLOCKS
… from the inner solar system (e.g., ordinary and enstatite chondrites) are H-poor relative to carbonaceous chondrites. Similarly, all melted planetesimals are commonly assumed to be anhydrous. However, recent analyses of enstatite chondrites (ECs), which are formed in the inner solar system and …
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Halogens and trace elements in subduction zones
… chlorine in upper mantle minerals (forsterite, enstatite and pyrope) and halogen partitioning between aqueous fluids and these minerals were investigated by piston-cylinder experiments at 1100 °C and 2.6 GPa. Chlorine solubility in forsterite, enstatite and pyrope is below the ppm level, and it …
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Iron Isotope Cosmochemistry
… samples including carbonaceous, ordinary, and enstatite chondrites, aubrites, brachinites, HED meteorites: howardites, eucrites and diogenites), martian meteorites, angrites, lunar meteorites, lunar regolith and ungrouped meteorites. I discuss iron isotope fractionations among these …
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Experimental investigation of the fluid driven carbonation of serpentinites and spinel-peridotites: implications for the carbon and trace element cycle in the forearc region of the mantle wedge
… stability, magnesite is stable with talc, talc+enstatite and enstatite±forsterite. Excess aluminium derived from the consumed serpentine or pyroxenes leads to the formation of chlorite and kyanite. With progressing carbonation and decreasing CO2 activity in the fluid, metasomatic reaction zones …
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Experimental investigation of the fluid driven carbonation of serpentinites and spinel-peridotites: implications for the carbon and trace element cycle in the forearc region of the mantle wedge
… stability, magnesite is stable with talc, talc+enstatite and enstatite±forsterite. Excess aluminium derived from the consumed serpentine or pyroxenes leads to the formation of chlorite and kyanite. With progressing carbonation and decreasing CO2 activity in the fluid, metasomatic reaction zones …
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The chlorine isotope composition of chondrites : evidence for a single nebular reservoir and the effects of secondary processes on chondrite parent bodies
… chondrites from the carbonaceous, ordinary, and enstatite classes. Petrologic type 3 chondrites are the least equilibrated and are those most likely to retain primary nebular signatures. By analyzing unaltered, pristine, chondrites from each class, we can determine if chlorine isotope variations …
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Modeling target rock composition of two impact events
… the Dales Gorge–Kuruman pair corresponds to an enstatite chondrite, whereas the Paraburdoo–Reivilo pair reflects an ordinary chondrite source. Both impacts indicate contributions from continental crust and the lack of mantle-derived material, supporting the hypothesis that the younger …
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Planetary Materials Science and Astrobiology
… likely precursors to terrestrial planets (enstatite chondrites); and important possible planetary habitats including post-impact hydrothermal mineral deposits and their associated weathering assemblages; and the fossilization of records of an ecosystem based on the microbial leaching of …
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