Nutman, AP and Friend, CRL and Barker, SLL and McGregor, VR, Inventory and assessment of Palaeoarchaean gneiss terrains and detrital zircons in southern West Greenland, Precambrian Research, 135 pp. 281-314. ISSN 0301-9268 (2004) [Refereed Article]
Copyright 2004 Elsevier B.V.
There are two less known smaller bodies of Palaeoarchaean rocks north of the Nuuk region. The Qarliit Tasersuat assemblage consists of polyphase, migmatitic gneisses with lenses of mafic and siliceous rocks. Two SHRIMP zircon dates reveal 3600–3700 Ma rocks, strongly affected by ∼3600 and 2770 Ma metamorphisms. The Aasivik terrane also consists of polyphase migmatitic gneisses, and previous SHRIMP U/Pb zircon reconnaissance dating of three samples found components up to ∼3600 Ma old with strong reworking in 2720–2550 Ma events.
The West Greenland Archaean Craton is a collage of Palaeo- to Neoarchaean terranes, assembled in several Archaean events. Metasediments within post-Palaeoarchaean terranes are devoid of ≥3600 Ma detritus, but are dominated by zircons of the same age as major crust-forming TTG suites of their terrane. Metasediments along terrane boundaries, even those in contact with Palaeoarchaean terranes, contain very few (<5%) ≥3600 Ma detrital zircons. Therefore, these sediments are not a significant resource for ancient zircons. The scarcity of ≥3600 Ma detritus within these sediments supports a model that the Palaeoarchaean bodies (Færingehavn, Isukasia, Qarliit tasersuat and Aasivik) are allochthonous terranes captured within an Archaean accretionary system and comprise a tectonic assembly of juvenile crustal blocks with different age. The metasediments in contact with the Isukasia terrane are dominated by ∼3070 Ma detrital zircons and were first metamorphosed (along with the adjacent Isukasia terrane) at ∼2960 Ma. On the other hand, metasediments in contact with the Færingehavn terrane are dominated by ∼2831 Ma detrital zircons, and thus were deposited after sediments in contact with the Isukasia terrane had already been tectonically emplaced and metamorphosed. Although the Palaeoarchaean terranes were incorporated into the Archaean terrane collage at different times, they might have been spawned from a single larger body of ancient crust broken up from ∼3500 Ma onwards.
|Item Type:||Refereed Article|
|Keywords:||Palaeoarchaean, crustal evolution, zircons, Greenland|
|Research Division:||Earth Sciences|
|Objective Division:||Expanding Knowledge|
|Objective Group:||Expanding knowledge|
|Objective Field:||Expanding knowledge in the earth sciences|
|UTAS Author:||Barker, SLL (Dr Shaun Barker)|
|Web of Science® Times Cited:||112|
|Deposited By:||CODES ARC|
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