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Showing 1 to 20 of 25 for “"anorthite"”.
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Some Factors Affecting the Formation of Anorthite in the Solid State
Made available in DSpace on 2014-12-04T19:14:18Z (GMT). No. of bitstreams: 1 6206221.pdf: 1898521 bytes, checksum: d6b62683d2c2c811935c8286619e41d0 (MD5) Previous issue date: 1962
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An ion microprobe study of trace element partitioning between clinopyroxene and liquid in the diopside (CaMgSi2O6) - albite (NaAlSi3O8) - anorthite (CaAl2Si2O8) system
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981.
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The approach to equilibrium of mixtures of CaO, A1₂O₃, and SiO₂ heated to various temperatures
… approached when certain compositions of the anorthite-mullite-cristobalite and the anorthite-gehlenite-corundum compatibility triangles were fired to 1400° C. The effect on equilibrium of different raw materials used to form the compositions was also studied. Based on the results of the …
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The Elastic Behavior of Plagioclase Feldspar at High Pressure
… containing between 20 and 40 mol% of end-member anorthite. The calculated elastic compliance tensor sums at room pressure show a general stiffening with increasing anorthite component, small elastic changes at the C-1 to I-1 transition, and a dominantly first-order response at the P-1 to I-1 …
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Inferences on the Structure of Aluminosilicate Glasses: A High Resolution Solid-State Silicon-29 and Aluminum-27 Nuclear Magnetic Resonance Study (magic-Angle)
… glasses and glasses in the system anorthite-diopside-forsterite were examined by high resolution solid-state silicon-29 and aluminum-27 nuclear magnetic resonance (NMR) spectroscopy. High resolution spectra were obtained at high magnetic field strengths (11.7 and 8.45 Tesla) using …
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Investigation of structural phase transitions in minerals and analogue systems by high-temperature magic-angle-spinning nuclear magnetic resonance spectroscopy
… transitions (SPT's) in three different phases (anorthite CaAl$\sb2$Si$\sb2$O$\sb8$, Sr$\sb2$SiO$\sb4$, and AlPO$\sb4$-cristobalite) via high-resolution nuclear magnetic resonance spectroscopy using mostly magic-angle spinning (MAS) techniques. The results provide important insight into each of …
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Petrology of the Ashe Formation, Shortt's Knob area, Floyd County, Virginia
… + biotite occurs in the only carbonate outcrop. Anorthite content of plagioclase ranges between 18 and 40 mol % but depends on lithology. Amphibolite hornblendes have at least one A1<sup>IV</sup> per formula unit. Epidote group minerals have compositions generally <Ps₅ or >Ps₁₀ and the concept of …
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Documenting Magnatic Processes at Filicudi Island, Aeolian Arc, Italy: Integrating Quantitative Modeling and Plagioclase Textural and in situ Compositional Data
… resulting in monotonous textures and high anorthite contents. Within the shallower system, recharge from the deeper system and continued FC contributed to the compositional diversity observed on Filicudi Island.</p>
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Fundamental studies on ionomer glasses
… of calcium fluoride (fluorite) and anorthite. The anorthite phase crystallized from fluorite nuclei and, in effect, crystallization occurred by a bulk nucleation mechanism. The glass will also undergo significant crystallization to fluorite below the glass transition temperature, …
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Distribution of trace elements in olivines and proxenes - an experimental study
… spinel were crystallized in the ternary system anorthite-forsterite-silica to which trace amounts of the transition metal ions Cr³⁺, Fe²⁺, Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺ had been added. The resulting concentrations of the transition metal ions in the liquid and crystalline phases were determined …
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Stable isotope geochemistry of the Okenyenya igneous complex, Namibia : constraints on contamination and fluid interaction
… of 560ᵒC and 540ᵒC have been calculated for the anorthite-clinopyroxene and plagioclase-biotite mineral-pairs in the tholeiitic leucogabbro sample, respectively. The oxygen isotope data for the silicate minerals are consistent with contamination of the magmas by material having the oxygen isotope …
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Petrology and geochemistry of the recent eruption history at Rabaul Caldera, Papua New Guinea : implications for magmatic processes and recurring volcanic activity
… basalt-dacite magma interaction events (i.e., anorthite cores overgrown with thick andesine rims). The petrologic and geochemical observations made in this study indicate the shallow magma system at Rabaul Caldera has been subject to repeated mafic magma injection since, and also during, the …
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Petrology and geochemistry of the recent eruption history at Rabaul Caldera, Papua New Guinea : implications for magmatic processes and recurring volcanic activity
… basalt-dacite magma interaction events (i.e., anorthite cores overgrown with thick andesine rims). The petrologic and geochemical observations made in this study indicate the shallow magma system at Rabaul Caldera has been subject to repeated mafic magma injection since, and also during, the …
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Petrology of the Numabin Bay intrusions, Reindeer Lake, Saskatchewan
… diffraction revealed: (1) a general decrease in anorthite content of the plagioclase and in the amounts of plagioclase, hornblende,and biotite; (2) an increase in the percentage of K feldspar; and (3) no consistent variation in the proportion of quartz towards the core of the pluton. Textures and …
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Optical and X-ray study of the low plagioclases
… the product, αβγ, which correlates linearly to anorthite content, confirm the presence of two structural discontinuities in the low plagioclase series. The angular attitude of the two optic axes and of the principal vibration directions plotted stereographically relative to b* (at S = 0, E= 0) …
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Studies of Magmatic Systems
… phase relations in the ternary feldspar and anorthite-diopside-albite systems to constrain the parameters used in the modeling. MI data are consistent with melt evolution from a basaltic parent via a fractional crystallization mainly of pyroxene and feldspars. These data and the results from …
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Ionic Mobility In Stuffed-Silica Minerals
… the feldspar minerals albite, K-feldspar and anorthite. The low-frequency dielectric properties of all of the minerals have been investigated from room temperature to 1100 K. At each temperature, the dielectric constant, conductivity and dielectric loss were determined over a range of …
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Calculation of temperature - oxygen fugacity tables for H₂-CO₂ gas mixtures at one atmosphere total pressure, and an investigation of the zoisite-clinozoisite transition
… crystals grown from seeded mixtures of anorthite, calcite, hematite and silica glass at 6500 bars and 650°C are shown to bracket the transition loop between Pistacite 3.2 (Ca₂Al<sub>2.90</sub>Fe<sub>0.10</sub>Si₃O₁₂(OH)) and Pistacite 12.6 …
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Formation conditions of plagioclase-bearing type I chondrules in CO chondrites : a study of natural samples and experimental analogs
… the presence of a Na-rich atmosphere, and with anorthite seeds present in the starting material. Experimental run products closely resemble textures of type I chondrules in ordinary and carbonaceous chondrites. Olivine is commonly poikilitically enclosed in euhedral low-Ca pyroxene. Ca-pyroxene …
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Evolution of chemical composition along river drainage networks
… correction) in surface waters suggests that anorthite and albite are the dominant minerals within the entire basin, and they are weathering rapidly (silicon to Na + K ≥4) with the bisiallitization type of weathering (silica to alumina >2). Human influences on river chemistry in the …
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