Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland
Pb-isotopic data for magnetite from amphibolites in the Nagssugtoqidian orogen, central West Greenland, have been used to trace their source characteristics and the timing of metamorphism. Analyses of the magnetite define a Pb-Pb isochron age of 1726 ± 7 Ma. The magnetite is metamorphic in origin, a...
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Geological Survey of Denmark and Greenland
2006
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ftdoajarticles:oai:doaj.org/article:4773570b1ea24faba5e55bb778880819 2023-05-15T15:23:20+02:00 Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland Frei, Robert Stendal, Henrik Secher, Karsten 2006-12-01T00:00:00Z https://doaj.org/article/4773570b1ea24faba5e55bb778880819 EN eng Geological Survey of Denmark and Greenland http://www.geus.dk/publications/bull/nr11/nr11_p101-114.pdf https://doaj.org/toc/1604-8156 1604-8156 https://doaj.org/article/4773570b1ea24faba5e55bb778880819 Geological Survey of Denmark and Greenland Bulletin, Vol 11, Pp 101-114 (2006) Pb isotopes magnetite Nagssugtoqidian orogen Palaeoproterozoic pegmatites Pb stepwise leaching supracrustal Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 article 2006 ftdoajarticles 2022-12-31T00:18:27Z Pb-isotopic data for magnetite from amphibolites in the Nagssugtoqidian orogen, central West Greenland, have been used to trace their source characteristics and the timing of metamorphism. Analyses of the magnetite define a Pb-Pb isochron age of 1726 ± 7 Ma. The magnetite is metamorphic in origin, and the 1726 Ma age is interpreted as a cooling age through the closing temperature of magnetite at ~600°C. Some of the amphibolites in this study come from the Naternaq supracrustal rocks in the northern Nagssugtoqidian orogen, which host the Naternaq sulphide deposit and may be part ofthe Nordre Strømfjord supracrustal suite, which was deposited at around 1950 Ma ago.Pb-isotopic signatures of magnetite from the Arfersiorfik quartz diorite in the central Nagssugtoqidian orogen are compatible with published whole-rock Pb-isotopic data from this suite; previous work has shown that it is a product of subduction-related calc-alkaline magmatism between 1920 and 1870 Ma. Intrusion of pegmatites occurred at around 1800 Ma in both the central and the northernparts of the orogen. Pegmatite ages have been determined by Pb stepwise leaching analyses of allanite and monazite, and source characteristics of Pb point to an origin of the pegmatites by melting of the surrounding late Archaean and Palaeoproterozoic country rocks. Hydrothermal activity took place after pegmatite emplacement and continued below the closure temperature of magnetite at 1800–1650 Ma. Because of the relatively inert and refractory nature of magnetite, Pb-isotopic measurements from this mineral may be of help to understand the metamorphic evolution of geologicallycomplex terrains. Article in Journal/Newspaper Arfersiorfik Greenland Nordre strømfjord Geological Survey of Denmark and Greenland Bulletin Directory of Open Access Journals: DOAJ Articles Greenland Naternaq ENVELOPE(-51.883,-51.883,68.333,68.333) Nordre Strømfjord ENVELOPE(-52.500,-52.500,67.533,67.533) |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Pb isotopes magnetite Nagssugtoqidian orogen Palaeoproterozoic pegmatites Pb stepwise leaching supracrustal Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Pb isotopes magnetite Nagssugtoqidian orogen Palaeoproterozoic pegmatites Pb stepwise leaching supracrustal Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 Frei, Robert Stendal, Henrik Secher, Karsten Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland |
topic_facet |
Pb isotopes magnetite Nagssugtoqidian orogen Palaeoproterozoic pegmatites Pb stepwise leaching supracrustal Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 |
description |
Pb-isotopic data for magnetite from amphibolites in the Nagssugtoqidian orogen, central West Greenland, have been used to trace their source characteristics and the timing of metamorphism. Analyses of the magnetite define a Pb-Pb isochron age of 1726 ± 7 Ma. The magnetite is metamorphic in origin, and the 1726 Ma age is interpreted as a cooling age through the closing temperature of magnetite at ~600°C. Some of the amphibolites in this study come from the Naternaq supracrustal rocks in the northern Nagssugtoqidian orogen, which host the Naternaq sulphide deposit and may be part ofthe Nordre Strømfjord supracrustal suite, which was deposited at around 1950 Ma ago.Pb-isotopic signatures of magnetite from the Arfersiorfik quartz diorite in the central Nagssugtoqidian orogen are compatible with published whole-rock Pb-isotopic data from this suite; previous work has shown that it is a product of subduction-related calc-alkaline magmatism between 1920 and 1870 Ma. Intrusion of pegmatites occurred at around 1800 Ma in both the central and the northernparts of the orogen. Pegmatite ages have been determined by Pb stepwise leaching analyses of allanite and monazite, and source characteristics of Pb point to an origin of the pegmatites by melting of the surrounding late Archaean and Palaeoproterozoic country rocks. Hydrothermal activity took place after pegmatite emplacement and continued below the closure temperature of magnetite at 1800–1650 Ma. Because of the relatively inert and refractory nature of magnetite, Pb-isotopic measurements from this mineral may be of help to understand the metamorphic evolution of geologicallycomplex terrains. |
format |
Article in Journal/Newspaper |
author |
Frei, Robert Stendal, Henrik Secher, Karsten |
author_facet |
Frei, Robert Stendal, Henrik Secher, Karsten |
author_sort |
Frei, Robert |
title |
Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland |
title_short |
Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland |
title_full |
Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland |
title_fullStr |
Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland |
title_full_unstemmed |
Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland |
title_sort |
precambrian crustal evolution and cretaceous–palaeogene faulting in west greenland: 207pb-206pb dating of magnetite, monazite and allanite in the central and northern nagssugtoqidian orogen, west greenland |
publisher |
Geological Survey of Denmark and Greenland |
publishDate |
2006 |
url |
https://doaj.org/article/4773570b1ea24faba5e55bb778880819 |
long_lat |
ENVELOPE(-51.883,-51.883,68.333,68.333) ENVELOPE(-52.500,-52.500,67.533,67.533) |
geographic |
Greenland Naternaq Nordre Strømfjord |
geographic_facet |
Greenland Naternaq Nordre Strømfjord |
genre |
Arfersiorfik Greenland Nordre strømfjord Geological Survey of Denmark and Greenland Bulletin |
genre_facet |
Arfersiorfik Greenland Nordre strømfjord Geological Survey of Denmark and Greenland Bulletin |
op_source |
Geological Survey of Denmark and Greenland Bulletin, Vol 11, Pp 101-114 (2006) |
op_relation |
http://www.geus.dk/publications/bull/nr11/nr11_p101-114.pdf https://doaj.org/toc/1604-8156 1604-8156 https://doaj.org/article/4773570b1ea24faba5e55bb778880819 |
_version_ |
1766354043026800640 |