Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland
Middle Cambrian basaltic flows, lapilli tuffs, and their feeder pipes, on the Avalon Peninsula, Newfoundland, show high Nb/Y and low Zr/Nb ratios and high concentrations of incompatible elements, such as Nb and Zr, which are typical of alkaline rocks. The compositions of relict clinopyroxenes are co...
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1985
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crcansciencepubl:10.1139/e85-168 2024-09-15T18:19:58+00:00 Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland Greenough, John D. Papezik, V. S. 1985 http://dx.doi.org/10.1139/e85-168 http://www.nrcresearchpress.com/doi/pdf/10.1139/e85-168 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 22, issue 11, page 1594-1601 ISSN 0008-4077 1480-3313 journal-article 1985 crcansciencepubl https://doi.org/10.1139/e85-168 2024-07-25T04:10:06Z Middle Cambrian basaltic flows, lapilli tuffs, and their feeder pipes, on the Avalon Peninsula, Newfoundland, show high Nb/Y and low Zr/Nb ratios and high concentrations of incompatible elements, such as Nb and Zr, which are typical of alkaline rocks. The compositions of relict clinopyroxenes are consistent with these conclusions. Relatively low Mg′ values and low CaO and high TiO 2 concentrations show that the flows represent evolved compositions. Petrographic evidence and trends in trace-element data indicate that the range of bulk-rock compositions in the feeder pipes can be related to precipitation of augite, plagioclase, and olivine as well as late removal of Fe–Ti oxides and apatite. The negative correlation (shown by noncumulus rocks) between Mg′ and Al 2 O 3 , the relatively high Mg′ values of the flows, and the alkaline nature of the rocks distinguish them from most flood basalts and relate them to rift basalts. Low Al 2 O 3 concentrations at the highest Mg′ values may be related to genesis in a garnet-rich mantle source under high pressures. These continental alkali basalts provide evidence that this portion of Avalonian terrane experienced tension during the Cambrian. Article in Journal/Newspaper Newfoundland Canadian Science Publishing Canadian Journal of Earth Sciences 22 11 1594 1601 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
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English |
description |
Middle Cambrian basaltic flows, lapilli tuffs, and their feeder pipes, on the Avalon Peninsula, Newfoundland, show high Nb/Y and low Zr/Nb ratios and high concentrations of incompatible elements, such as Nb and Zr, which are typical of alkaline rocks. The compositions of relict clinopyroxenes are consistent with these conclusions. Relatively low Mg′ values and low CaO and high TiO 2 concentrations show that the flows represent evolved compositions. Petrographic evidence and trends in trace-element data indicate that the range of bulk-rock compositions in the feeder pipes can be related to precipitation of augite, plagioclase, and olivine as well as late removal of Fe–Ti oxides and apatite. The negative correlation (shown by noncumulus rocks) between Mg′ and Al 2 O 3 , the relatively high Mg′ values of the flows, and the alkaline nature of the rocks distinguish them from most flood basalts and relate them to rift basalts. Low Al 2 O 3 concentrations at the highest Mg′ values may be related to genesis in a garnet-rich mantle source under high pressures. These continental alkali basalts provide evidence that this portion of Avalonian terrane experienced tension during the Cambrian. |
format |
Article in Journal/Newspaper |
author |
Greenough, John D. Papezik, V. S. |
spellingShingle |
Greenough, John D. Papezik, V. S. Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland |
author_facet |
Greenough, John D. Papezik, V. S. |
author_sort |
Greenough, John D. |
title |
Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland |
title_short |
Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland |
title_full |
Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland |
title_fullStr |
Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland |
title_full_unstemmed |
Petrology and geochemistry of Cambrian volcanic rocks from the Avalon Peninsula, Newfoundland |
title_sort |
petrology and geochemistry of cambrian volcanic rocks from the avalon peninsula, newfoundland |
publisher |
Canadian Science Publishing |
publishDate |
1985 |
url |
http://dx.doi.org/10.1139/e85-168 http://www.nrcresearchpress.com/doi/pdf/10.1139/e85-168 |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_source |
Canadian Journal of Earth Sciences volume 22, issue 11, page 1594-1601 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e85-168 |
container_title |
Canadian Journal of Earth Sciences |
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22 |
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11 |
container_start_page |
1594 |
op_container_end_page |
1601 |
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1810458319606775808 |