A buried Palaeoproterozoic spreading ridge in the northern Nagssugtoqidian orogen, West Greenland

Adam A. Garde, Julie A. Hollis

Research output: Chapter in Book/Report/Conference proceedingChapter in bookResearchpeer-review

28 Citations (Scopus)

Abstract

Ophiolitic rocks on two small island groups in the northern Nagssugtoqidian orogen, West Greenland, shed new light on the eastern Laurentian Palaeoproterozoic plate-tectonic collage. The islands expose amphibolite-facies (520-550 °C, 2.6-3.0 kbar) tholeiitic pillow lava, black chloritic shale, manganiferous banded iron formation (BIF), podded chert, jasper, graded andalusite-staurolite schist with numerous sills, and terrigenous sandstone, an association that occurs today in oceanic spreading zones undergoing burial in forearc trenches. Deformation is weak, with upright folds preserving original younging. U-Pb detrital zircon ages indicate derivation from Archaean, 1890 Ma, and 1850 Ma sources. Occurring north of the Archaean Aasiaat domain that partly escaped Nagssugtoqidian deformation, the sequence pinpoints a new SSE-dipping Palaeoproterozoic subduction zone that links up in the NE with the Disko Bugt suture at the Nagssugtoqidian-Rinkian boundary. This solves an enigma of the previous plate-tectonic model, in which the Arfersiorfik magmatic arc in the central Nagssugtoqidian orogen was located within its own suture zone, and helps to explain why the Nagssugtoqidian-Rinkian system is so broad. It also explains previously recognized geochemical and Pb-isotopic compositional breaks in orthogneisses in the Kangaatsiaq region, and greatly simplifies correlation with adjacent eastern Canadian orogens in Baffin Island and Labrador.

Original languageEnglish
Title of host publicationThe evolving Continents
Subtitle of host publicationUnderstanding processes of continental growth
EditorsT.M. Kusky, M.-G. Zhai, W. Xiao
PublisherGeological Society of London
Pages213-234
Number of pages22
ISBN (Print)978-1-86239-303-5
DOIs
Publication statusPublished - 2010

Publication series

NameGeological Society Special Publication
PublisherGeological Society of London
Volume338
ISSN (Print)0305-8719

Programme Area

  • Programme Area 4: Mineral Resources

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