| Title | Torngat ultramafic lamprophyres and their relation to the North Atlantic Alkaline Province |
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| Author | Tappe, S; Jenner, G A; Foley, S F; Heaman, L; Besserer, D; Kjarsgaard, B A ; Ryan, B |
| Source | Selected papers from the Eighth International Kimberlite Conference, volume 1: the C. Roger Clement volume; by Mitchell, R H (ed.); Grutter, H S (ed.); Heaman, L M (ed.); Scott Smith, B H (ed.); Lithos
vol. 76, issue 1-4, 2004 p. 491-518, https://doi.org/10.1016/j.lithos.2004.03.040 |
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| Year | 2004 |
| Alt Series | Geological Survey of Canada, Contribution Series 2003317 |
| Publisher | Elsevier BV |
| Meeting | Eighth International Kimberlite Conference; Victoria, BC; CA; June 22-27, 2003 |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| Related | This publication is related to Ultramafic lamprophyre dyke
swarm, Torngat Mountains, Quebec and Labrador: mineralogy and geochemistry |
| File format | html; pdf (Adobe Acrobat Reader) |
| Province | Eastern offshore region |
| NTS | 13; 14; 15; 16; 23; 24; 25; 26A; 26B; 26C; 26D; 26E; 26F; 26G; 26H; 33; 34; 35; 36A; 36B; 36C; 36D; 36E; 36F; 36G; 36H |
| Area | North Atlantic; Canada; Greenland |
| Lat/Long WENS | -80.0000 -36.0000 66.0000 52.0000 |
| Subjects | economic geology; geochemistry; geochronology; igneous and metamorphic petrology; tectonics; ultramafic rocks; dykes; olivine; phlogopite; carbonatites; lamprophyres; carbonatites; rifting; rifts; plate
tectonics; diamond; uranium lead dating; Opening of the Iapetus Ocean |
| Illustrations | location maps; tables; geochemical plots; photomicrographs; graphs |
| Program | NSERC Natural Sciences and Engineering Research Council of
Canada |
| Released | 2004 09 01 |
| Abstract | Geological mapping and diamond exploration in northern Quebec and Labrador has revealed an undeformed ultramafic dyke swarm in the northern Torngat Mountains. The dyke rocks are dominated by an
olivine-phlogopite mineralogy and contain varying amounts of primary carbonate. Their mineralogy, mineral compositional trends and the presence of typomorphic minerals (e.g. kimzeyitic garnet), indicate that these dykes comprise an ultramafic
lamprophyre suite grading into carbonatite. Recognized rock varieties are aillikite, mela-aillikite and subordinate carbonatite. Carbonatite and aillikite have in common high carbonate content and a lack of clinopyroxene. In contrast, mela-aillikites
are richer in mafic silicate minerals, in particular clinopyroxene and amphibole, and contain only small amounts of primary carbonate. The modal mineralogy and textures of the dyke varieties are gradational, indicating that they represent end-members
in a compositional continuum.
The Torngat ultramafic lamprophyres are characterized by high but variable MgO (10-25 wt.%), CaO (5-20 wt.%), TiO2 (3-10 wt.%) and K2O (1-4 wt.%), but low SiO2 (22-37 wt.%) and Al2O3 (2-6 wt.%). Higher SiO2,
Al2O3, Na2O and lower CO2 content distinguish the mela-aillikites from the aillikites. Whereas the bulk rock major and trace element concentrations of the aillikites and mela-aillikites overlap, there is no fractional crystallization relation between
them. The major and trace element characteristics imply related parental magmas, with minor olivine and Cr-spinel fractionation accounting for intra-group variation.
The Torngat ultramafic lamprophyres have a Neoproterozoic age and are
spatially and compositionally closely related with the Neoproterozoic ultramafic lamprophyres from central West Greenland. Ultramafic potassic-to-carbonatitic magmatism occurred in both eastern Laurentia and western Baltica during the Late
Neoproterozoic. It can be inferred from the emplacement ages of the alkaline complexes and timing of Late Proterozoic processes in the North Atlantic region that this volatile-rich, deep-seated igneous activity was a distal effect of the breakup of
Rodinia. This occurred during and/or after the rift-to-drift transition that led to the opening of the Iapetus Ocean. |
| GEOSCAN ID | 215388 |
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