Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland
An extremely heterogeneous section of upper mantle exposed over 2 km² in the Springers Hill area of the Lewis Hills Massif, Bay of Islands Ophiolite Complex, consists of two distinct associations: low-Al peridotites and pyroxenites (LALPP), and high-Al peridotites, pyroxenites and gabbros (HALPPG)....
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Memorial University of Newfoundland
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ftmemorialuniv:oai:research.library.mun.ca:6815 2023-10-01T03:57:39+02:00 Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland Edwards, Stephen John 1991 application/pdf https://research.library.mun.ca/6815/ https://research.library.mun.ca/6815/1/StephenJohnEdwards.pdf https://research.library.mun.ca/6815/3/StephenJohnEdwards.pdf en eng Memorial University of Newfoundland https://research.library.mun.ca/6815/1/StephenJohnEdwards.pdf https://research.library.mun.ca/6815/3/StephenJohnEdwards.pdf Edwards, Stephen John <https://research.library.mun.ca/view/creator_az/Edwards=3AStephen_John=3A=3A.html> (1991) Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland. Doctoral (PhD) thesis, Memorial University of Newfoundland. thesis_license Thesis NonPeerReviewed 1991 ftmemorialuniv 2023-09-03T06:46:04Z An extremely heterogeneous section of upper mantle exposed over 2 km² in the Springers Hill area of the Lewis Hills Massif, Bay of Islands Ophiolite Complex, consists of two distinct associations: low-Al peridotites and pyroxenites (LALPP), and high-Al peridotites, pyroxenites and gabbros (HALPPG). These represent the processes of magma and fluid generation, migration and evolution in the mantle wedge of a subduction zone. -- The LALPP have Cr-spinel of Cr# = 47-90, Mg# = 23-65, and fo-med in the order of harzburgite-orthopyroxenite (and associated dunite and chromititel-clinopyroxenite (and associated dunite, chromitite and websterite). Harzburgite is a refractory residue from partial melting and complete removal of low-Ti tholeiitic magma. This harzburgite has straight, positively sloping chondrite-normalized REE patterns and Pd/lr < 1. Dykes of orthopyroxenite have U-shaped chondrite-normalized PEE patterns and very high Pd/lr ratios, and formed from hydrous. As-saturated magma of boninitic affinity, which previously had fractionated significant quantities of Cr-spinel and relatively minor olivine. By mechanical mixing or magmatic impregnation, a component of orthopyroxenite was added to some harzburgites; these harzburgites have U-shaped chondrite-normalized REE patterns and Pd/lr >1. Dykes of cllnopyroxenite formed from LREE-depleted, high Pd/lr, S-saturated, low-Ti tholeiitic magma. The LALPP formed at P ≤ 7-8 kbar in upwelling asthenosphere (T=1300 ± lOCC) below a zone of crustal accretion in a supra-subduction zone environment. -- The HALPPG contain spinel of approximately Cr# = 30, Mg# = 65, and comprise dunite, wehrlite, olivine cllnopyroxenite, gabbro and amphibole peridotite. The HALPPG formed in the lithosphere (T = 900 ± 100°C) at P = 5-9 kbar by combined assimilation and crystal fractionation, which involved fluid-bearing magma and LALPP. The replacement of LALPP by HALPPG involved dissolution of ortho- and clinopyroxene, precipitation of clinopyroxene, plagioclase, Ca-amphibole and ... Thesis Newfoundland Memorial University of Newfoundland: Research Repository |
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Memorial University of Newfoundland: Research Repository |
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ftmemorialuniv |
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English |
description |
An extremely heterogeneous section of upper mantle exposed over 2 km² in the Springers Hill area of the Lewis Hills Massif, Bay of Islands Ophiolite Complex, consists of two distinct associations: low-Al peridotites and pyroxenites (LALPP), and high-Al peridotites, pyroxenites and gabbros (HALPPG). These represent the processes of magma and fluid generation, migration and evolution in the mantle wedge of a subduction zone. -- The LALPP have Cr-spinel of Cr# = 47-90, Mg# = 23-65, and fo-med in the order of harzburgite-orthopyroxenite (and associated dunite and chromititel-clinopyroxenite (and associated dunite, chromitite and websterite). Harzburgite is a refractory residue from partial melting and complete removal of low-Ti tholeiitic magma. This harzburgite has straight, positively sloping chondrite-normalized REE patterns and Pd/lr < 1. Dykes of orthopyroxenite have U-shaped chondrite-normalized PEE patterns and very high Pd/lr ratios, and formed from hydrous. As-saturated magma of boninitic affinity, which previously had fractionated significant quantities of Cr-spinel and relatively minor olivine. By mechanical mixing or magmatic impregnation, a component of orthopyroxenite was added to some harzburgites; these harzburgites have U-shaped chondrite-normalized REE patterns and Pd/lr >1. Dykes of cllnopyroxenite formed from LREE-depleted, high Pd/lr, S-saturated, low-Ti tholeiitic magma. The LALPP formed at P ≤ 7-8 kbar in upwelling asthenosphere (T=1300 ± lOCC) below a zone of crustal accretion in a supra-subduction zone environment. -- The HALPPG contain spinel of approximately Cr# = 30, Mg# = 65, and comprise dunite, wehrlite, olivine cllnopyroxenite, gabbro and amphibole peridotite. The HALPPG formed in the lithosphere (T = 900 ± 100°C) at P = 5-9 kbar by combined assimilation and crystal fractionation, which involved fluid-bearing magma and LALPP. The replacement of LALPP by HALPPG involved dissolution of ortho- and clinopyroxene, precipitation of clinopyroxene, plagioclase, Ca-amphibole and ... |
format |
Thesis |
author |
Edwards, Stephen John |
spellingShingle |
Edwards, Stephen John Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland |
author_facet |
Edwards, Stephen John |
author_sort |
Edwards, Stephen John |
title |
Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland |
title_short |
Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland |
title_full |
Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland |
title_fullStr |
Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland |
title_full_unstemmed |
Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland |
title_sort |
magmatic and fluid processes in the upper mantle: a study of the bay of islands ophiolite complex, newfoundland |
publisher |
Memorial University of Newfoundland |
publishDate |
1991 |
url |
https://research.library.mun.ca/6815/ https://research.library.mun.ca/6815/1/StephenJohnEdwards.pdf https://research.library.mun.ca/6815/3/StephenJohnEdwards.pdf |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_relation |
https://research.library.mun.ca/6815/1/StephenJohnEdwards.pdf https://research.library.mun.ca/6815/3/StephenJohnEdwards.pdf Edwards, Stephen John <https://research.library.mun.ca/view/creator_az/Edwards=3AStephen_John=3A=3A.html> (1991) Magmatic and fluid processes in the Upper Mantle: a study of the Bay of Islands ophiolite complex, Newfoundland. Doctoral (PhD) thesis, Memorial University of Newfoundland. |
op_rights |
thesis_license |
_version_ |
1778529600077299712 |