Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 62 for “"orthopyroxene"”.
-
Experimental studies of iron-magnesium order-disorder in orthopyroxene: Equilibrium, kinetics, and applications
… kinetics of the Fe-Mg order-disorder process in orthopyroxene were studied by means of thermal annealing experiments at fix fO₂ condition, and single crystal X-raydiffraction to determine the site occupancies. The behavior of Mn on the equilibrium fractionation of Fe-Mg was studied by a series of …
-
Textural and Chemical Relations Among Spinel-Sapphirine-Garnet-Orthopyroxene, Salt Hill Emery Mine, Cortlandt Complex, N.Y.
… sapphirine – garnet (0.25), garnet – orthopyroxene (0.28), rather than directly from spinel to higher-silica minerals which would overstep intermediate reaction steps. However, observed reaction textures indicate the latter more complex behavior in which spinel may have reaction rims …
-
Sound velocity study of natural orthopyroxenes with varying iron content
Determination of the acoustic wave velocities of orthopyroxene as a function of composition is essential to identify the underlying causes of seismic heterogeneity. Such laboratory measurements are essential to determine the structure, composition and temperature variability of the upper mantle. …
-
An experimental approach to thermal and solar weathering of Mercury's crust
… 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 …
-
An investigation into the dissolution of pyroxene : a precursor to mineral carbonation of PGM tailings in South Africa
… highlighted the slow extraction of cations from orthopyroxene, the major Mg-host. The low reactivity of the orthopyroxene resulted in an overall low conversion of tailings to carbonates with only 30 % for Ca, 3 % for Mg and 9 % for Fe. Under similar experimental leach conditions, ~100 % …
-
Formation of mineralogical zonations in ophiolites through reactive porous flow : a modeling study
… using COMSOL v. 4.1. I developed a model for an orthopyroxene dissolution front based on the model of Chadam et al. (1986, Reactive infiltration instabilities, IMA Journal of Applied Mathematics, v. 36, p.207-221). This model includes the strong nonlinearity feedback that has been invoked to lead …
-
The Influence of Variable Oxygen Fugacity on the Source Depths for Lunar High-Titanium Ultramafic Glasses
… of multiple saturation where both olivine and orthopyroxene are stable on the liquidus. The investigated compositions are the Apollo 17 Orange glass (A17O, 9.1 wt.% TiO₂), Apollo 15 Red glass (A15R, 13.8 wt.% TiO₂), and Apollo 14 Black glass (A14B, 16.4 wt.% TiO₂). Experimental temperatures and …
-
INTO THE STRUCTURE OF THE PERMIAN DEEP CONTINENTAL CRUST: A MULTISCALE APPROACH TO RECONSTRUCT MIGMATIZATION IN THE VALPELLINE SERIES (DENT BLANCHE TECTONIC SYSTEM, WESTERN ITALIAN ALPS)
… assemblages (i.e., garnet-, cordierite- and orthopyroxene-bearing), amphibolite and marble, intruded by aplite and pegmatite. Melt production in metapelite and locally in amphibolite occurred during the development of the regional foliation. Quantitative microstructural and mineral-chemical …
-
The primary structures and fabrics of the upper mantle and lower oceanic crust from ophiolite complexes
… which is often compositionally banded into orthopyroxene-rich and olivine-rich segregation layers. Dunitic sheets and pods are common in some of the areas studied. They are highly variable in size and shape (up to 1 1/2km diameter in Troodos) and some contain concentrations of chromite ore. …
-
A geochemical and stable isotope study of some rocks from the Bandelierkop formation, southern marginal zone of the Limpopo Belt, South Africa( vol.1 Text)
… from orthoamphibole gneisses in the south to orthopyroxene-bearing rocks in the north of the SMZ terrane, is a function of changing biotite composition and/or decreasing water activities rather than an increase in metamorphic temperatures. In contrast to the major and trace element data, the …
-
Absarokites from the Western Mexican Volcanic Belt : constraints on mantle wedge conditions
… wt% H2O is multiply saturated with olivine and orthopyroxene as liquidus phases at 1.6 GPa and 1400°C. At the same pressure clinopyroxene appears 30°C below the liquidus. With a H2O content of -5.1 wt% composition M.102 is multiply saturated with olivine and orthopyroxene on the liquidus at 1.7 …
-
Absarokites from the Western Mexican Volcanic Belt : constraints on mantle wedge conditions
… wt% H20 is multiply saturated with olivine and orthopyroxene as liquidus phases at 1.6 GPa and 14000C. At the same pressure clinopyroxene appears 300C below the liquidus. With a H20 content of -5.1 wt% composition M.102 is multiply saturated with olivine and orthopyroxene on the liquidus at 1.7 …
-
Hydrous melt generation in the Earth's mantle
… Chapter 1, the melting behavior of an olivine + orthopyroxene +/- spinel - bearing fertile mantle composition is investigated as a function of variable pressure and water content. The experimental results are used to calibrate a model that can predict the pressure and temperature or the …
-
A study of mantle inclusions in the Koffiefontein Kimberlite Pipe, South Africa
… The heavy mineral concentrate contained garnet, orthopyroxene, opaque minerals and clinopyroxene in order of abundance. The opaque minerals were chromite and ilmenite. The chemical compositions of most of the concentrate grains do not match the mineral compositions found in xenoliths, or …
-
A study of mantle inclusions in the Koffiefontein Kimberlite pipe, South Africa
… The heavy mineral concentrate contained garnet, orthopyroxene, opaque minerals and clinopyroxene in order of abundance. The opaque minerals were chromite and ilmenite. The chemical compositions of most of the concentrate grains do not match the mineral compositions found in xenolith s, or …
-
Geochemical Evolution at White Island, New Zealand
… dacites containing phenocrysts of plagioclase, orthopyroxene, and clinopyroxene. A glassy matrix containing crystallites surrounds the phenocrysts. Both mineral and silicate melt inclusions occur in all three phenocryst phases. Inclusions of plagioclase occur in pyroxenes and inclusions of …
-
The petrology and geochemistry of Precaldera Magmas, Long Valley Caldera, Eastern California
… flow sequences (> 24 km³), (2) local orthopyroxene -phyric silicic trachyandesite flows (> I km³), and (3) sparsely -phyric orthopyroxene -hornblende -plagioclase quartz latite dome-flows and coarsely -phyric biotite -hornblende -plagioclase quartz latite dome-flows ( > 4 km³) erupted …
-
A pertographic and geochemical study of selected peridotitic and pyroxenitic xenoliths from the three kimberlite localities in the Lac de Gras region, Northwest Territories, Canada
… then determined using 'garnet-olivine, garnet-orthopyroxene and trace element geothermobarometers (TNi, Per).
-
A petrographical and mineralogical investigation of the rocks of the Bushveld Igneous Complex in the Tauteshoogte-Roossenekal area of the Eastern Transvaal
… from rocks of the Layered Sequence, namely orthopyroxene, plagioclase, apatite and the sulphides of the Upper Zone. In Subzone A of the Main Zone, the orthopyroxene is present as cumulus crystals, but it changes in texture to ophitic in the lower half of Subzone B where small discrete grains …
-
Documenting multiple metasomatic events within the Finero phlogopite peridotite using chlorine isotopes, Ivrea zone, Italy
… (3) a single crosscutting phlogopite + orthopyroxene segregation, and (4) cumulate amphibole peridotites. Group 1 peridotites range in textures from massive, showing few deformation features, to samples with well-developed olivine + orthopyroxene ± phlogopite ± amphibole shape-preferred …
Page 1 of 4