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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ftunivwindsor:oai:scholar.uwindsor.ca:environmentalsciencepub-1108 2023-06-11T04:12:13+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 2018-01-01T08:00:00Z application/pdf https://scholar.uwindsor.ca/environmentalsciencepub/104 https://doi.org/10.1080/09853111.2018.1427408 https://scholar.uwindsor.ca/context/environmentalsciencepub/article/1108/viewcontent/TGDA_2017_0027R1_R.pdf unknown Scholarship at UWindsor https://scholar.uwindsor.ca/environmentalsciencepub/104 doi:10.1080/09853111.2018.1427408 https://scholar.uwindsor.ca/context/environmentalsciencepub/article/1108/viewcontent/TGDA_2017_0027R1_R.pdf Earth & Environmental Sciences Publications Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Earth Sciences Environmental Sciences text 2018 ftunivwindsor https://doi.org/10.1080/09853111.2018.1427408 2023-05-06T18:52:19Z 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. Text Greenland University of Windsor, Ontario: Scholarship at UWindsor Canada Greenland Geodinamica Acta 30 1 84 99 |
institution |
Open Polar |
collection |
University of Windsor, Ontario: Scholarship at UWindsor |
op_collection_id |
ftunivwindsor |
language |
unknown |
topic |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Earth Sciences Environmental Sciences |
spellingShingle |
Archaean layered intrusion megacrystic anorthosite leucogabbro magma chamber suprasubduction zone Earth Sciences Environmental Sciences Polat, Ali 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 Environmental Sciences |
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 |
Text |
author |
Polat, Ali |
author_facet |
Polat, Ali |
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 at UWindsor |
publishDate |
2018 |
url |
https://scholar.uwindsor.ca/environmentalsciencepub/104 https://doi.org/10.1080/09853111.2018.1427408 https://scholar.uwindsor.ca/context/environmentalsciencepub/article/1108/viewcontent/TGDA_2017_0027R1_R.pdf |
geographic |
Canada Greenland |
geographic_facet |
Canada Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Earth & Environmental Sciences Publications |
op_relation |
https://scholar.uwindsor.ca/environmentalsciencepub/104 doi:10.1080/09853111.2018.1427408 https://scholar.uwindsor.ca/context/environmentalsciencepub/article/1108/viewcontent/TGDA_2017_0027R1_R.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 |
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1768387915649384448 |