The petrology and petrogenesis of the North Motzfeldt Centre, Gardar Province, South Greenland
Abstract
North Motzfeldt is an intrusive igneous centre within the Igaliku (formerly spelt Igaliko) complex, Gardar Province, South Greenland. A detailed field description of the centre is given, with preliminary geochemical and isotopic data. The North Motzfeldt centre is intruded into Ketilidian granitoid basement rocks, and current exposure retains parts of the original roof against earlier Gardar eruptives and elastic sediments of the Eriksfjord formation. The unconformity between the Ketilidian and the overlying Eriksfjord is believed to have been crucial in the siting of the centre. The centre is subdivided into two major units, NM1 and NM2. This was followed by significant peralkaline nepheline microsyenite in sheets, characterized by rare element-rich accessory minerals including rinkite-mosandrite, pyrochlore and lavenite. A significant microsyenite body is called NM3. A preliminary Rb-Sr isochron of 1226 +/- 27 Ma indicates a far younger age for the centre than previously thought (similar to 1350 Ma). Cross-cutting relationships between North Motzfeldt and rocks of the adjacent Motzfeldt centre require a reappraisal of the chronology of Motzfeldt magmatism. We suggest that rocks previously believed to comprise the Motzfeldt centre represent the products of multiple phases of magmatism from Early- to Mid-Gardar times.
Citation
Finch , A A , Goodenough , K M , Salmon , H M & Andersen , T 2001 , ' The petrology and petrogenesis of the North Motzfeldt Centre, Gardar Province, South Greenland ' , Mineralogical Magazine , vol. 65 , no. 6 , pp. 759-774 . https://doi.org/10.1180/0026461016560007
Publication
Mineralogical Magazine
Status
Peer reviewed
ISSN
0026-461XType
Journal article
Rights
Copyright © The Mineralogical Society. his work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.1180/0026461016560007
Description
The Carnegie Trust for the Universities of Scotland, The Percy Sladen Trust, The Royal Geographical Society, The Mineralogical Society of Great Britain and Ireland, NERC and the University of Luton gave financial assistance for the present study. Radiometric studies formed part of a collaborative programme between AAF and TA funded by the British Council.Collections
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