An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase
Anorthosite-bearing layered intrusions are unique to the Archaean rock record and are abundant in the Archaean craton of southern West Greenland and the Superior Province of Canada. These layered intrusions consist mainly of ultramafic rocks, gabbros, leucogabbros and anorthosites, and typically con...
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Taylor & Francis Group
2018
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Online Access: | https://doi.org/10.1080/09853111.2018.1427408 https://doaj.org/article/06dd482995a84cbbad92a8e80c3e1da5 |
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ftdoajarticles:oai:doaj.org/article:06dd482995a84cbbad92a8e80c3e1da5 2023-05-15T16:28:22+02:00 An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase Ali Polat Fred J. Longstaffe Robert Frei 2018-01-01T00:00:00Z https://doi.org/10.1080/09853111.2018.1427408 https://doaj.org/article/06dd482995a84cbbad92a8e80c3e1da5 EN eng Taylor & Francis Group http://dx.doi.org/10.1080/09853111.2018.1427408 https://doaj.org/toc/0985-3111 https://doaj.org/toc/1778-3593 0985-3111 1778-3593 doi:10.1080/09853111.2018.1427408 https://doaj.org/article/06dd482995a84cbbad92a8e80c3e1da5 Geodinamica Acta, Vol 30, Iss 1, Pp 84-99 (2018) Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Engineering geology. Rock mechanics. Soil mechanics. Underground construction TA703-712 Geology QE1-996.5 article 2018 ftdoajarticles https://doi.org/10.1080/09853111.2018.1427408 2022-12-31T11:17:40Z Anorthosite-bearing layered intrusions are unique to the Archaean rock record and are abundant in the Archaean craton of southern West Greenland and the Superior Province of Canada. These layered intrusions consist mainly of ultramafic rocks, gabbros, leucogabbros and anorthosites, and typically contain high-Ca (>An70) megacrystic (2–30 cm in diameter) plagioclase in anorthosite and leucogabbro units. They are spatially and temporally associated with basalt-dominated greenstone belts and are intruded by syn-to post-tectonic granitoid rocks. The layered intrusions, greenstone belts and granitoids all share the geochemical characteristics of Phanerozoic subduction zone magmas, suggesting that they formed mainly in a suprasubduction zone setting. Archaean anorthosite-bearing layered intrusions and spatially associated greenstone belts are interpreted to be fragments of oceanic crust, representing dismembered subduction-related ophiolites. We suggest that large degrees of partial melting (25–35%) in the hotter (1500–1600 °C) Archaean upper mantle beneath rifting arcs and backarc basins produced shallow, kilometre-scale hydrous magma chambers. Field observations suggest that megacrystic anorthosites were generated at the top of the magma chambers, or in sills, dykes and pods in the oceanic crust. The absence of high-Ca megacrystic anorthosites in post-Archaean layered intrusions and oceanic crust reflects the decline of mantle temperatures resulting from secular cooling of the Earth. Article in Journal/Newspaper Greenland Directory of Open Access Journals: DOAJ Articles Canada Greenland Geodinamica Acta 30 1 84 99 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Engineering geology. Rock mechanics. Soil mechanics. Underground construction TA703-712 Geology QE1-996.5 |
spellingShingle |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Engineering geology. Rock mechanics. Soil mechanics. Underground construction TA703-712 Geology QE1-996.5 Ali Polat Fred J. Longstaffe Robert Frei An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase |
topic_facet |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Engineering geology. Rock mechanics. Soil mechanics. Underground construction TA703-712 Geology QE1-996.5 |
description |
Anorthosite-bearing layered intrusions are unique to the Archaean rock record and are abundant in the Archaean craton of southern West Greenland and the Superior Province of Canada. These layered intrusions consist mainly of ultramafic rocks, gabbros, leucogabbros and anorthosites, and typically contain high-Ca (>An70) megacrystic (2–30 cm in diameter) plagioclase in anorthosite and leucogabbro units. They are spatially and temporally associated with basalt-dominated greenstone belts and are intruded by syn-to post-tectonic granitoid rocks. The layered intrusions, greenstone belts and granitoids all share the geochemical characteristics of Phanerozoic subduction zone magmas, suggesting that they formed mainly in a suprasubduction zone setting. Archaean anorthosite-bearing layered intrusions and spatially associated greenstone belts are interpreted to be fragments of oceanic crust, representing dismembered subduction-related ophiolites. We suggest that large degrees of partial melting (25–35%) in the hotter (1500–1600 °C) Archaean upper mantle beneath rifting arcs and backarc basins produced shallow, kilometre-scale hydrous magma chambers. Field observations suggest that megacrystic anorthosites were generated at the top of the magma chambers, or in sills, dykes and pods in the oceanic crust. The absence of high-Ca megacrystic anorthosites in post-Archaean layered intrusions and oceanic crust reflects the decline of mantle temperatures resulting from secular cooling of the Earth. |
format |
Article in Journal/Newspaper |
author |
Ali Polat Fred J. Longstaffe Robert Frei |
author_facet |
Ali Polat Fred J. Longstaffe Robert Frei |
author_sort |
Ali Polat |
title |
An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase |
title_short |
An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase |
title_full |
An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase |
title_fullStr |
An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase |
title_full_unstemmed |
An overview of anorthosite-bearing layered intrusions in the Archaean craton of southern West Greenland and the Superior Province of Canada: implications for Archaean tectonics and the origin of megacrystic plagioclase |
title_sort |
overview of anorthosite-bearing layered intrusions in the archaean craton of southern west greenland and the superior province of canada: implications for archaean tectonics and the origin of megacrystic plagioclase |
publisher |
Taylor & Francis Group |
publishDate |
2018 |
url |
https://doi.org/10.1080/09853111.2018.1427408 https://doaj.org/article/06dd482995a84cbbad92a8e80c3e1da5 |
geographic |
Canada Greenland |
geographic_facet |
Canada Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Geodinamica Acta, Vol 30, Iss 1, Pp 84-99 (2018) |
op_relation |
http://dx.doi.org/10.1080/09853111.2018.1427408 https://doaj.org/toc/0985-3111 https://doaj.org/toc/1778-3593 0985-3111 1778-3593 doi:10.1080/09853111.2018.1427408 https://doaj.org/article/06dd482995a84cbbad92a8e80c3e1da5 |
op_doi |
https://doi.org/10.1080/09853111.2018.1427408 |
container_title |
Geodinamica Acta |
container_volume |
30 |
container_issue |
1 |
container_start_page |
84 |
op_container_end_page |
99 |
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1766018012117204992 |