Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane
We report the results of new mapping, whole-rock major, minor, and trace-element geochemistry, and petrography for metaigneous rocks from the Mount Veta area in the westernmost part of the allochthonous Yukon–Tanana terrane (YTT) in east-central Alaska. These rocks include tonalitic mylonite gneiss...
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crcansciencepubl:10.1139/cjes-2013-0004 2024-09-15T18:41:27+00:00 Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane Dusel-Bacon, Cynthia Day, Warren C. Aleinikoff, John N. McFarlane, Chris 2013 http://dx.doi.org/10.1139/cjes-2013-0004 http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2013-0004 http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2013-0004 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 50, issue 8, page 826-846 ISSN 0008-4077 1480-3313 journal-article 2013 crcansciencepubl https://doi.org/10.1139/cjes-2013-0004 2024-09-05T04:11:14Z We report the results of new mapping, whole-rock major, minor, and trace-element geochemistry, and petrography for metaigneous rocks from the Mount Veta area in the westernmost part of the allochthonous Yukon–Tanana terrane (YTT) in east-central Alaska. These rocks include tonalitic mylonite gneiss and mafic metaigneous rocks from the Chicken metamorphic complex and the Nasina and Fortymile River assemblages. Whole-rock trace-element data from the tonalitic gneiss, whose igneous protolith was dated by SHRIMP U–Pb zircon geochronology at 332.6 ± 5.6 Ma, indicate derivation from tholeiitic arc basalt. Whole-rock analyses of the mafic rocks suggest that greenschist-facies rocks from the Chicken metamorphic complex, a mafic metavolcanic rock from the Nasina assemblage, and an amphibolite from the Fortymile River assemblage formed as island-arc tholeiite in a back-arc setting; another Nasina assemblage greenschist has MORB geochemical characteristics, and another mafic metaigneous rock from the Fortymile River assemblage has geochemical characteristics of calc-alkaline basalt. Our geochemical results imply derivation in an arc and back-arc spreading region within the allochthonous YTT crustal fragment, as previously proposed for correlative units in other parts of the terrane. We also describe the petrography and geochemistry of a newly discovered tectonic lens of Alpine-type metaharzburgite. The metaharzburgite is interpreted to be a sliver of lithospheric mantle from beneath the Seventymile ocean basin or from sub-continental mantle lithosphere of the allochthonous YTT or the western margin of Laurentia that was tectonically emplaced within crustal rocks during closure of the Seventymile ocean basin and subsequently displaced and fragmented by faults. Article in Journal/Newspaper Alaska Yukon Canadian Science Publishing Canadian Journal of Earth Sciences 50 8 826 846 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
We report the results of new mapping, whole-rock major, minor, and trace-element geochemistry, and petrography for metaigneous rocks from the Mount Veta area in the westernmost part of the allochthonous Yukon–Tanana terrane (YTT) in east-central Alaska. These rocks include tonalitic mylonite gneiss and mafic metaigneous rocks from the Chicken metamorphic complex and the Nasina and Fortymile River assemblages. Whole-rock trace-element data from the tonalitic gneiss, whose igneous protolith was dated by SHRIMP U–Pb zircon geochronology at 332.6 ± 5.6 Ma, indicate derivation from tholeiitic arc basalt. Whole-rock analyses of the mafic rocks suggest that greenschist-facies rocks from the Chicken metamorphic complex, a mafic metavolcanic rock from the Nasina assemblage, and an amphibolite from the Fortymile River assemblage formed as island-arc tholeiite in a back-arc setting; another Nasina assemblage greenschist has MORB geochemical characteristics, and another mafic metaigneous rock from the Fortymile River assemblage has geochemical characteristics of calc-alkaline basalt. Our geochemical results imply derivation in an arc and back-arc spreading region within the allochthonous YTT crustal fragment, as previously proposed for correlative units in other parts of the terrane. We also describe the petrography and geochemistry of a newly discovered tectonic lens of Alpine-type metaharzburgite. The metaharzburgite is interpreted to be a sliver of lithospheric mantle from beneath the Seventymile ocean basin or from sub-continental mantle lithosphere of the allochthonous YTT or the western margin of Laurentia that was tectonically emplaced within crustal rocks during closure of the Seventymile ocean basin and subsequently displaced and fragmented by faults. |
author2 |
McFarlane, Chris |
format |
Article in Journal/Newspaper |
author |
Dusel-Bacon, Cynthia Day, Warren C. Aleinikoff, John N. |
spellingShingle |
Dusel-Bacon, Cynthia Day, Warren C. Aleinikoff, John N. Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane |
author_facet |
Dusel-Bacon, Cynthia Day, Warren C. Aleinikoff, John N. |
author_sort |
Dusel-Bacon, Cynthia |
title |
Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane |
title_short |
Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane |
title_full |
Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane |
title_fullStr |
Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane |
title_full_unstemmed |
Geochemistry, petrography, and zircon U–Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon–Tanana terrane |
title_sort |
geochemistry, petrography, and zircon u–pb geochronology of paleozoic metaigneous rocks in the mount veta area of east-central alaska: implications for the evolution of the westernmost part of the yukon–tanana terrane |
publisher |
Canadian Science Publishing |
publishDate |
2013 |
url |
http://dx.doi.org/10.1139/cjes-2013-0004 http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2013-0004 http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2013-0004 |
genre |
Alaska Yukon |
genre_facet |
Alaska Yukon |
op_source |
Canadian Journal of Earth Sciences volume 50, issue 8, page 826-846 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/cjes-2013-0004 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
50 |
container_issue |
8 |
container_start_page |
826 |
op_container_end_page |
846 |
_version_ |
1810485860594876416 |