Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland
Harzburgite is a common rock type in ophiolites and alpine peridotites. It is considered to be typical of a residual mantle mineralogy, i.e., material left behind after periods of extensive mantle melting and melt–rock and fluid–rock interactions that produce a variety of basaltic melts. The process...
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crcansciencepubl:10.1139/e95-086 2024-09-15T18:20:01+00:00 Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland Edwards, Stephen J. Malpas, John 1995 http://dx.doi.org/10.1139/e95-086 http://www.nrcresearchpress.com/doi/pdf/10.1139/e95-086 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 32, issue 7, page 1046-1057 ISSN 0008-4077 1480-3313 journal-article 1995 crcansciencepubl https://doi.org/10.1139/e95-086 2024-07-25T04:10:08Z Harzburgite is a common rock type in ophiolites and alpine peridotites. It is considered to be typical of a residual mantle mineralogy, i.e., material left behind after periods of extensive mantle melting and melt–rock and fluid–rock interactions that produce a variety of basaltic melts. The processes by which these melts and residua are produced are complicated; therefore, to fully understand them, it is necessary to undertake detailed and integrated field, petrographic, and geochemical studies of large exposures of mantle material as part of the investigative process. Such a study in the Bay of Islands ophiolite exposed in the Lewis Hills of Newfoundland has enabled the identification of four major types of harzburgite, which represent examples of a complete spectrum of this rock type. Depleted, residual harzburgite and associated dunite, with positive-sloping rare earth element patterns, may develop U-shaped rare earth element patterns and a visible orthopyroxene enrichment by the introduction of a component of high-Mg, quartz-normative melt, or a hydrous fluid component with a high Si/Al ratio. Conversely, U-shaped rare earth element patterns and apparent orthopyroxene depletion may occur by the addition of low-Si/Al, hydrous fluid. Such enrichments and depletions of orthopyroxene by solution–precipitation reactions may result not only in the variety of harzburgite types, which on partial melting might produce a range of melt products, but also in fronts of harzburgite migrating through the mantle. Article in Journal/Newspaper Newfoundland Canadian Science Publishing Canadian Journal of Earth Sciences 32 7 1046 1057 |
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Canadian Science Publishing |
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description |
Harzburgite is a common rock type in ophiolites and alpine peridotites. It is considered to be typical of a residual mantle mineralogy, i.e., material left behind after periods of extensive mantle melting and melt–rock and fluid–rock interactions that produce a variety of basaltic melts. The processes by which these melts and residua are produced are complicated; therefore, to fully understand them, it is necessary to undertake detailed and integrated field, petrographic, and geochemical studies of large exposures of mantle material as part of the investigative process. Such a study in the Bay of Islands ophiolite exposed in the Lewis Hills of Newfoundland has enabled the identification of four major types of harzburgite, which represent examples of a complete spectrum of this rock type. Depleted, residual harzburgite and associated dunite, with positive-sloping rare earth element patterns, may develop U-shaped rare earth element patterns and a visible orthopyroxene enrichment by the introduction of a component of high-Mg, quartz-normative melt, or a hydrous fluid component with a high Si/Al ratio. Conversely, U-shaped rare earth element patterns and apparent orthopyroxene depletion may occur by the addition of low-Si/Al, hydrous fluid. Such enrichments and depletions of orthopyroxene by solution–precipitation reactions may result not only in the variety of harzburgite types, which on partial melting might produce a range of melt products, but also in fronts of harzburgite migrating through the mantle. |
format |
Article in Journal/Newspaper |
author |
Edwards, Stephen J. Malpas, John |
spellingShingle |
Edwards, Stephen J. Malpas, John Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland |
author_facet |
Edwards, Stephen J. Malpas, John |
author_sort |
Edwards, Stephen J. |
title |
Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland |
title_short |
Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland |
title_full |
Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland |
title_fullStr |
Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland |
title_full_unstemmed |
Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite, Newfoundland |
title_sort |
multiple origins for mantle harzburgites: examples from the lewis hills, bay of islands ophiolite, newfoundland |
publisher |
Canadian Science Publishing |
publishDate |
1995 |
url |
http://dx.doi.org/10.1139/e95-086 http://www.nrcresearchpress.com/doi/pdf/10.1139/e95-086 |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_source |
Canadian Journal of Earth Sciences volume 32, issue 7, page 1046-1057 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e95-086 |
container_title |
Canadian Journal of Earth Sciences |
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32 |
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7 |
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1046 |
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1057 |
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1810458377205055488 |