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Showing 1 to 20 of 27 for “"Pyroxenite"”.
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The roles of 1herzolite and garnet pyroxenite in the constitution of the upper mantle,
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1970.
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Ore breakage characterisation of UG2 deposits using the JK RBT
… the breakage properties of UG2 chromitite, pyroxenite, spotted anorthosite and mottled anorthosite grab samples from run-of-mine (RoM) ore stockpile (particle selection method) and cut drill core particles (cut core method). A mineralogical analysis of UG2 chromitite, pyroxenite, spotted …
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A heavy stable isotope approach to tracing mantle source and process
… how mantle lithology, such as recycled crust (pyroxenite), could be reflected in the stable isotope composition of the erupted melts, and the insights that heavy stable isotope data from basalts could provide into mantle source and process. Throughout this thesis, I investigate five stable …
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The 'Ins' and 'Outs' of the Bushveld Complex Upper Zone
… from the geochemical base of the Upper Zone (the Pyroxenite Marker) to the contact with the roof. On the basis of major element modeling and trace element equilibria I show that the bulk composition is not representative of the original magma composition, and therefore some magma must be missing. …
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Petrological and geochemical studies of an abyssal periodotite from the Atlantis II fracture zone
… with a crosscutting coarse-grained clinopyroxenite vein. One of the alteration veinlets contains rutile and ilmenite in association with plagioclase and amphibole. This veinlet is not related to the pyroxenite vein. In tenns of mineralogy, the composition of the major silicate minerals …
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… partition coefficients during silica-poor garnet pyroxenite melting for a suite of trace elements, including U and Th, at 2.5GPa and 1420-1450°C. Partition coefficients range from 0.0083+0.0006 to 0.020+0.002 for Th and 0.0094+0.0006 to 0.024+0.002 for U in Cpx, and are 0.0032+0.0004 for Th and …
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… partition coefficients during silica-poor garnet pyroxenite melting for a suite of trace elements, including U and Th, at 2.5GPa and 1420-1450°C. Partition coefficients range from 0.0083±0.0006 to 0.020±0.002 for Th and 0.0094±0.0006 to 0.024±0.002 for U in Cpx, and are 0.0032±0.0004 for Th and …
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Petrology of the Cenozoic igneous rocks of the Tinton district, Black Hills, South Dakota - Wyoming
… consanguinity between lamprophyre dikes and pyroxenite of the Mineral Hill alkalic ring dike complex. The lamprophyres may have evolved from a volatile rich fraction of the pyroxenite magma.</p> <p>Late-stage hydrothermal alteration affected all rocks in the Tinton district. A classic …
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A study of mantle inclusions in the Koffiefontein Kimberlite Pipe, South Africa
… unusually scarce. The predominant xenoliths are pyroxenites. Peridotites are rare and eclogites are very rare. The pyroxenites have been assigned to five categories. In general they show a clear metamorphic textural history with widespread evidence of exsolution, polygonisation and deformation. …
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A study of mantle inclusions in the Koffiefontein Kimberlite pipe, South Africa
… unusuaLly scarce. The predominant xenoliths are pyroxenites. Peridotites are rare and eclogites are very rare. The pyroxenites have been assigned to five categories. In general, they show a clear metamorphic textural history with widespread evidence of exsolution, polygonisation and deformation. …
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Petrology and contact relationships, SW portion PC Mullen Creek mafic complex, Medicine Bow Mts., Wy.
… interlayered rocks that originally ranged from pyroxenite to anorthosite but were dominantly gabbro and leucogabbro. Most of these rocks underwent regional medium-grade metamorphism to form amphibolite facies assemblages in which hornblende has replaced pyroxene, labradorite has remained stable …
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The geochemistry of the Gough Island basalts and their mantle source region
… garnet lherzolite or ~30-50% melting of a garnet pyroxenite source.
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Controls of Melt Genesis and Evolution at Buldir Volcano in the Western Aleutian Island Arc
… MORB-like (e.g., 87Sr/86Sr < 0.7027) pyroxenite or subducted basaltic source. Andesites and dacites from emergent volcanoes throughout the Aleutians often also have low abundances of middle and heavy rare-earth elements (REE's), but these characteristics are widely attributed to …
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The lattice preferred orientation of olivine in Beni Bousera Ultramafic Massif, Morocco
… to 100 meter scale zones which contain abundant pyroxenite dykes, dunite, harzburgite, and secondary lherzolite. These zones are interpreted as areas of focused melt percolation. Lattice preferred orientation (LPO) of olivine crystals from a sample transect across one of these zones was analyzed …
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The oxygen, carbon & hydrogen isotope geochemistry of the Phalaborwa Complex, South Africa
… magma pulses. This produced a main pipe of pyroxenite, carbonatite and foskorite (olivineapatite-magnetite-calcite) and many smaller syenite plugs around the pipe. The complex is the oldest known carbonatite in southern Africa and the only one known to host economic copper deposits. There …
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An investigation into the formation of the lower Main Zone in the eastern limb of the Bushveld complex, South Africa
… intruded the Main Zone at the level of the Pyroxenite Marker, forming the upper Main Zone. Copyright
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Supercontinental Inheritance and its Influence on Supercontinental Breakup: The Central Atlantic Magmatic Province and the Breakup of Pangea
… in olivine phenocrysts indicating a significant pyroxenite component in the source, interpreted here as a result of subduction metasomatism. Different collisional styles during the Alleghanian orogeny in the North and South may have led to the diachroneity of the rifting of Pangea. Furthermore, …
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Insights into the location, nature and influence of mantle heterogeneity in the Galápagos mantle plume
… the Galápagos Archipelago: (i) the presence of pyroxenite (recycled) components in the Galápagos mantle plume [Chapters 2 and 3]; (ii) the nature and implications of plume-ridge interaction in the Galápagos [Chapters 3 and 4]; (iii) the volatile content of the Galápagos mantle plume [Chapters 4 …
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Geochemical properties of the Beni Bousera (N. Morocco) peridotites : a field and laboratory approach to understanding melt infiltration and extraction in an orogenic peridotite massif
… of harzburgite, dunite, and veins and layers of pyroxenite are relatively common. A combined field and laboratory-based investigation of Beni Bousera has yielded a new dataset comprised of whole rock and mineral chemistry data that is used to suggest the massif is more heterogeneous than …
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Igneous life cycles: geochemistry of magma from mantle to surface and back again
… magmatism here. We argue for the importance of pyroxenite melting and suggest that metasomatism related to earlier subduction in this region were significant influences on mama compositions.
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