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...
Published in: | Geodinamica Acta |
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Online Access: | https://ir.lib.uwo.ca/earthpub/26 https://doi.org/10.1080/09853111.2018.1427408 https://ir.lib.uwo.ca/context/earthpub/article/1027/viewcontent/Polat_et_al.__2018_.pdf |
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ftunivwestonta:oai:ir.lib.uwo.ca:earthpub-1027 2023-10-01T03:56:20+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 Polat, Ali Longstaffe, Fred J Frei, Robert 2018-01-01T08:00:00Z application/pdf https://ir.lib.uwo.ca/earthpub/26 https://doi.org/10.1080/09853111.2018.1427408 https://ir.lib.uwo.ca/context/earthpub/article/1027/viewcontent/Polat_et_al.__2018_.pdf unknown Scholarship@Western https://ir.lib.uwo.ca/earthpub/26 doi:doi.org/10.1080/09853111.2018.1427408 https://ir.lib.uwo.ca/context/earthpub/article/1027/viewcontent/Polat_et_al.__2018_.pdf Earth Sciences Publications Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Earth Sciences Geochemistry Geology Tectonics and Structure article 2018 ftunivwestonta https://doi.org/10.1080/09853111.2018.1427408 2023-09-03T07:00:59Z 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 The University of Western Ontario: Scholarship@Western Canada Greenland Geodinamica Acta 30 1 84 99 |
institution |
Open Polar |
collection |
The University of Western Ontario: Scholarship@Western |
op_collection_id |
ftunivwestonta |
language |
unknown |
topic |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Earth Sciences Geochemistry Geology Tectonics and Structure |
spellingShingle |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Earth Sciences Geochemistry Geology Tectonics and Structure Polat, Ali Longstaffe, Fred J Frei, Robert 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 Earth Sciences Geochemistry Geology Tectonics and Structure |
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 |
Polat, Ali Longstaffe, Fred J Frei, Robert |
author_facet |
Polat, Ali Longstaffe, Fred J Frei, Robert |
author_sort |
Polat, Ali |
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 |
Scholarship@Western |
publishDate |
2018 |
url |
https://ir.lib.uwo.ca/earthpub/26 https://doi.org/10.1080/09853111.2018.1427408 https://ir.lib.uwo.ca/context/earthpub/article/1027/viewcontent/Polat_et_al.__2018_.pdf |
geographic |
Canada Greenland |
geographic_facet |
Canada Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Earth Sciences Publications |
op_relation |
https://ir.lib.uwo.ca/earthpub/26 doi:doi.org/10.1080/09853111.2018.1427408 https://ir.lib.uwo.ca/context/earthpub/article/1027/viewcontent/Polat_et_al.__2018_.pdf |
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 |
_version_ |
1778525766418432000 |