Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries
Eocene volcanic flow and dike rocks from the Beringian margin have arc characteristics, implying a convergent history for this region during the early Tertiary. The extrusive rocks are basalt, basaltic andesite, andesite, and minor dacite and rhyolite. The intrusive sample is from a quartz diorite d...
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crcansciencepubl:10.1139/e89-125 2024-06-23T07:51:46+00:00 Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries Davis, Alicé S. Pickthorn, Leda-Beth G. Valuer, Tracy L. Marlow, Michael S. 1989 http://dx.doi.org/10.1139/e89-125 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-125 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 26, issue 7, page 1474-1490 ISSN 0008-4077 1480-3313 journal-article 1989 crcansciencepubl https://doi.org/10.1139/e89-125 2024-06-13T04:10:53Z Eocene volcanic flow and dike rocks from the Beringian margin have arc characteristics, implying a convergent history for this region during the early Tertiary. The extrusive rocks are basalt, basaltic andesite, andesite, and minor dacite and rhyolite. The intrusive sample is from a quartz diorite dike intruding serpentinized peridotite. Major-element oxide contents, particularly FeO*/MgO versus SiO 2 , identify both tholeiitic and calc-alkalic basalt; more silicic lavas have calc-alkalic affinities. Consistent with volcanic-arc compositions, spidergrams show pronounced Nb–Ta depletion and alkali enrichment relative to light-rare-earth-element (LREE) abundance. Chondrite-normalized REE plots show relatively flat patterns, with only slight LREE enrichment for tholeiitic compositions and greater LREE enrichment and lower heavy-rare-earth-element (HREE) abundance for calc-alkalic compositions. The samples, particularly those with calc-alkalic compositions, are rich in plagioclase that is strongly zoned; the more silicic samples contain orthopyroxene, clinopyroxene, and primary amphibole. The quartz diorite dike contains iron-rich almandine phenocrysts that appear to be magmatic, suggesting emplacement at great depth near the base of the crust or upper mantle.Chemical and mineralogical compositions are similar to those of modern Aleutian-arc lavas. They also resemble volcanic-arc compositions from western mainland Alaska, although greater chemical diversity and a stronger continental influence are observed in the Alaskan mainland rocks.Early Eocene ages of 54.4–50.2 Ma for the Beringian samples are well constrained by conventional K–Ar ages of nine plagioclase separates and by concordant 40 Ar/ 39 Ar incremental heating and total-fusion experiments. A concordant U–Pb zircon age of 53 Ma for the quartz-diorite dike is in good agreement with the K–Ar data.Plate motion studies of the North Pacific Ocean indicate more northerly directed subduction prior to the Tertiary and a continuous belt of arc-type volcanism ... Article in Journal/Newspaper Bering Sea Alaska Canadian Science Publishing Bering Sea Pacific Canadian Journal of Earth Sciences 26 7 1474 1490 |
institution |
Open Polar |
collection |
Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
Eocene volcanic flow and dike rocks from the Beringian margin have arc characteristics, implying a convergent history for this region during the early Tertiary. The extrusive rocks are basalt, basaltic andesite, andesite, and minor dacite and rhyolite. The intrusive sample is from a quartz diorite dike intruding serpentinized peridotite. Major-element oxide contents, particularly FeO*/MgO versus SiO 2 , identify both tholeiitic and calc-alkalic basalt; more silicic lavas have calc-alkalic affinities. Consistent with volcanic-arc compositions, spidergrams show pronounced Nb–Ta depletion and alkali enrichment relative to light-rare-earth-element (LREE) abundance. Chondrite-normalized REE plots show relatively flat patterns, with only slight LREE enrichment for tholeiitic compositions and greater LREE enrichment and lower heavy-rare-earth-element (HREE) abundance for calc-alkalic compositions. The samples, particularly those with calc-alkalic compositions, are rich in plagioclase that is strongly zoned; the more silicic samples contain orthopyroxene, clinopyroxene, and primary amphibole. The quartz diorite dike contains iron-rich almandine phenocrysts that appear to be magmatic, suggesting emplacement at great depth near the base of the crust or upper mantle.Chemical and mineralogical compositions are similar to those of modern Aleutian-arc lavas. They also resemble volcanic-arc compositions from western mainland Alaska, although greater chemical diversity and a stronger continental influence are observed in the Alaskan mainland rocks.Early Eocene ages of 54.4–50.2 Ma for the Beringian samples are well constrained by conventional K–Ar ages of nine plagioclase separates and by concordant 40 Ar/ 39 Ar incremental heating and total-fusion experiments. A concordant U–Pb zircon age of 53 Ma for the quartz-diorite dike is in good agreement with the K–Ar data.Plate motion studies of the North Pacific Ocean indicate more northerly directed subduction prior to the Tertiary and a continuous belt of arc-type volcanism ... |
format |
Article in Journal/Newspaper |
author |
Davis, Alicé S. Pickthorn, Leda-Beth G. Valuer, Tracy L. Marlow, Michael S. |
spellingShingle |
Davis, Alicé S. Pickthorn, Leda-Beth G. Valuer, Tracy L. Marlow, Michael S. Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries |
author_facet |
Davis, Alicé S. Pickthorn, Leda-Beth G. Valuer, Tracy L. Marlow, Michael S. |
author_sort |
Davis, Alicé S. |
title |
Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries |
title_short |
Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries |
title_full |
Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries |
title_fullStr |
Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries |
title_full_unstemmed |
Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries |
title_sort |
petrology and age of volcanic-arc rocks from the continental margin of the bering sea: implications for early eocene relocation of plate boundaries |
publisher |
Canadian Science Publishing |
publishDate |
1989 |
url |
http://dx.doi.org/10.1139/e89-125 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-125 |
geographic |
Bering Sea Pacific |
geographic_facet |
Bering Sea Pacific |
genre |
Bering Sea Alaska |
genre_facet |
Bering Sea Alaska |
op_source |
Canadian Journal of Earth Sciences volume 26, issue 7, page 1474-1490 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e89-125 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
26 |
container_issue |
7 |
container_start_page |
1474 |
op_container_end_page |
1490 |
_version_ |
1802642906790494208 |