Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland
Within the southern Nagssugtoqidian orogen in West Greenland metamorphic terrains of both Archaean and Palaeoproterozoic ages occur with metamorphic grade varying from low amphibolite facies to granulite facies. The determination of the relative ages of the different metamorphic terrains is greatly...
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ftjgeusbullet:oai:geusjournals.org:article/4930 2023-05-15T16:27:22+02:00 Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland Korstgård, John A. Møller Stensgaard, Bo Rasmussen, Thorkild M. 2006-12-05 application/pdf https://geusbulletin.org/index.php/geusb/article/view/4930 https://doi.org/10.34194/geusb.v11.4930 eng eng Geological Survey of Denmark and Greenland (GEUS) https://geusbulletin.org/index.php/geusb/article/view/4930/10595 https://geusbulletin.org/index.php/geusb/article/view/4930 doi:10.34194/geusb.v11.4930 GEUS Bulletin; Vol. 11 (2006): Precambrian crustal evolution and Cretaceous-Palaeogene faulting in West Greenland; 179-184 2597-2154 2597-2162 aeromagnetic data magnetic anomalies metamorphic facies Nagssugtoqidian orogen West Greenland info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article. 2006 ftjgeusbullet https://doi.org/10.34194/geusb.v11.4930 2022-03-15T17:22:19Z Within the southern Nagssugtoqidian orogen in West Greenland metamorphic terrains of both Archaean and Palaeoproterozoic ages occur with metamorphic grade varying from low amphibolite facies to granulite facies. The determination of the relative ages of the different metamorphic terrains is greatly aided by the intrusion of the 2 Ga Kangâmiut dyke swarm along a NNE trend. In Archaean areas dykes cross-cut gneiss structures, and the host gneisses are in amphibolite to granulite facies. Along Itilleq strong shearing in an E–W-oriented zone caused retrogression of surrounding gneisses to low amphibolite facies. Within this Itivdleq shear zone Kangâmiut dykes follow the E–W shear fabrics giving the impression that dykes were reoriented by the shearing. However, the dykes remain largely undeformed and unmetamorphosed, indicating that the shear zone was established prior to dyke emplacement and that the orientation of the dykes here was governed by the shear fabric. Metamorphism and deformation north of Itilleq involve both dykes and host gneisses, and the metamorphic grade is amphibolite facies increasing to granulite facies at the northern boundary of the southern Nagssugtoqidian orogen. Here a zone of strong deformation, the Ikertôq thrust zone, coincides roughly with the amphibolite–granulite facies transition. Total magnetic field intensity anomalies from aeromagnetic data coincide spectacularly with metamorphic boundaries and reflect changes in content of the magnetic minerals at facies transitions. Even the nature of facies transitions is apparent. Static metamorphic boundaries are gradual whereas dynamic boundaries along deformation zones are abrupt. Article in Journal/Newspaper Greenland Itilleq GEUS Bulletin (Geological Survey of Denmark and Greenland) Greenland Geological Survey of Denmark and Greenland (GEUS) Bulletin 11 179 184 |
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Open Polar |
collection |
GEUS Bulletin (Geological Survey of Denmark and Greenland) |
op_collection_id |
ftjgeusbullet |
language |
English |
topic |
aeromagnetic data magnetic anomalies metamorphic facies Nagssugtoqidian orogen West Greenland |
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aeromagnetic data magnetic anomalies metamorphic facies Nagssugtoqidian orogen West Greenland Korstgård, John A. Møller Stensgaard, Bo Rasmussen, Thorkild M. Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland |
topic_facet |
aeromagnetic data magnetic anomalies metamorphic facies Nagssugtoqidian orogen West Greenland |
description |
Within the southern Nagssugtoqidian orogen in West Greenland metamorphic terrains of both Archaean and Palaeoproterozoic ages occur with metamorphic grade varying from low amphibolite facies to granulite facies. The determination of the relative ages of the different metamorphic terrains is greatly aided by the intrusion of the 2 Ga Kangâmiut dyke swarm along a NNE trend. In Archaean areas dykes cross-cut gneiss structures, and the host gneisses are in amphibolite to granulite facies. Along Itilleq strong shearing in an E–W-oriented zone caused retrogression of surrounding gneisses to low amphibolite facies. Within this Itivdleq shear zone Kangâmiut dykes follow the E–W shear fabrics giving the impression that dykes were reoriented by the shearing. However, the dykes remain largely undeformed and unmetamorphosed, indicating that the shear zone was established prior to dyke emplacement and that the orientation of the dykes here was governed by the shear fabric. Metamorphism and deformation north of Itilleq involve both dykes and host gneisses, and the metamorphic grade is amphibolite facies increasing to granulite facies at the northern boundary of the southern Nagssugtoqidian orogen. Here a zone of strong deformation, the Ikertôq thrust zone, coincides roughly with the amphibolite–granulite facies transition. Total magnetic field intensity anomalies from aeromagnetic data coincide spectacularly with metamorphic boundaries and reflect changes in content of the magnetic minerals at facies transitions. Even the nature of facies transitions is apparent. Static metamorphic boundaries are gradual whereas dynamic boundaries along deformation zones are abrupt. |
format |
Article in Journal/Newspaper |
author |
Korstgård, John A. Møller Stensgaard, Bo Rasmussen, Thorkild M. |
author_facet |
Korstgård, John A. Møller Stensgaard, Bo Rasmussen, Thorkild M. |
author_sort |
Korstgård, John A. |
title |
Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland |
title_short |
Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland |
title_full |
Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland |
title_fullStr |
Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland |
title_full_unstemmed |
Magnetic anomalies and metamorphic boundaries in the southern Nagssugtoqidian orogen, West Greenland |
title_sort |
magnetic anomalies and metamorphic boundaries in the southern nagssugtoqidian orogen, west greenland |
publisher |
Geological Survey of Denmark and Greenland (GEUS) |
publishDate |
2006 |
url |
https://geusbulletin.org/index.php/geusb/article/view/4930 https://doi.org/10.34194/geusb.v11.4930 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Itilleq |
genre_facet |
Greenland Itilleq |
op_source |
GEUS Bulletin; Vol. 11 (2006): Precambrian crustal evolution and Cretaceous-Palaeogene faulting in West Greenland; 179-184 2597-2154 2597-2162 |
op_relation |
https://geusbulletin.org/index.php/geusb/article/view/4930/10595 https://geusbulletin.org/index.php/geusb/article/view/4930 doi:10.34194/geusb.v11.4930 |
op_doi |
https://doi.org/10.34194/geusb.v11.4930 |
container_title |
Geological Survey of Denmark and Greenland (GEUS) Bulletin |
container_volume |
11 |
container_start_page |
179 |
op_container_end_page |
184 |
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1766016518286475264 |