气候变化领域集成服务门户(CCPortal): Gneiss-forming events in the Saglek Block; Labrador; a reappraisal of the Uivak gneiss

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DOI	10.1007/s00531-019-01677-y
	Gneiss-forming events in the Saglek Block; Labrador; a reappraisal of the Uivak gneiss
	Sałacińska A.; Kusiak M.A.; Whitehouse M.J.; Dunkley D.J.; Wilde S.A.; Kielman R.; Król P.
发表日期	2019
ISSN	14373254
起始页码	753
结束页码	778
卷号	108 期号:3
英文摘要	The Archean gneiss complex of the Saglek Block of Labrador is a part of the North Atlantic Craton, and is correlated with southern West Greenland, both being metamorphosed during a ca. 2.7 Ga event. The main component of the complex is the Eoarchean Uivak orthogneiss, which includes lenses of the Nulliak supracrustal assemblage. Both lithologies are cut by the mafic Saglek metadykes. The Uivak gneisses have been divided into Uivak I grey gneiss and Uivak II augen gneiss. The former underwent ca. 3.6 Ga high-T metamorphism prior to the intrusion of the latter. However, the exact age, nature, and extent of Uivak II gneiss are poorly understood. We present geochemical and geochronological results for both these orthogneisses to help refine the various hypotheses that have been proposed concerning the nature of their protoliths. Magmatic ages of 3746 ± 5 and 3717 ± 6 Ma are consistent with previous estimates for the age of Uivak I gneiss. Uivak II augen gneiss from Maidmonts Island, where there is a clear intrusive relationship between the Uivak II and Uivak I gneissic protoliths, has an age of 3325 ± 3 Ma. This is similar to an homogeneous grey gneiss from St. John’s Harbour, with an age of 3318 ± 5 Ma. Grey gneiss from Big Island is distinctively younger (3219 ± 7 Ma), and equivalent to the ca. 3.24 Ga Lister gneiss. Our study shows that granitic gneisses classified as Uivak II were emplaced 200–300 million years after ca. 3.6 Ga metamorphism and deformation of the Uivak I gneiss. The igneous protolith of Uivak II gneiss pre-dates the Lister gneiss by about 100 Ma. The Uivak I and Lister gneisses are geochemically similar, and are both Tonalite–Trondhjemite–Granodiorite (TTG) gneisses, whereas the Uivak II gneiss is a granitoid partially derived from pre-existing crust. We propose abandoning the term ‘Uivak II gneiss’, and renaming ca. 3.3 Ga granitoids, after the type locality, as Maidmonts gneiss. This restricts the term ‘Uivak gneiss’ to Eoarchean TTG gneisses and removes the necessity for subdividing them into Uivak I and II. © 2019, The Author(s).
英文关键词	Saglek block; TTG gneiss; Uivak gneiss; U–Pb geochronology
语种	英语
scopus关键词	geochemistry; geochronology; gneiss; granitoid; lithology; magma; metamorphism; uranium-lead dating; Arctic; Canada; Greenland; Labrador; Newfoundland and Labrador; North Atlantic Craton
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147856
作者单位	Institute of Geological Sciences, Polish Academy of Sciences, Twarda 51/55 St., Warsaw, 00818, Poland; Swedish Museum of Natural History, Stockholm, SE104 05, Sweden; Faculty of Earth Sciences, University of Silesia in Katowice, Sosnowiec, 41205, Poland; School of Earth and Planetary Sciences, Curtin University, PO Box U1987, Perth, WA 6845, Australia
推荐引用方式 GB/T 7714	Sałacińska A.,Kusiak M.A.,Whitehouse M.J.,et al. Gneiss-forming events in the Saglek Block; Labrador; a reappraisal of the Uivak gneiss[J],2019,108(3).
APA	Sałacińska A..,Kusiak M.A..,Whitehouse M.J..,Dunkley D.J..,Wilde S.A..,...&Król P..(2019).Gneiss-forming events in the Saglek Block; Labrador; a reappraisal of the Uivak gneiss.International Journal of Earth Sciences,108(3).
MLA	Sałacińska A.,et al."Gneiss-forming events in the Saglek Block; Labrador; a reappraisal of the Uivak gneiss".International Journal of Earth Sciences 108.3(2019).