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TitleNeoarchean disaggregation and reassembly of the Superior craton
AuthorBédard, J H; Harris, L B
SourceGeology 2014., https://doi.org/10.1130/G35770.1
Image
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20140199
PublisherGeological Society of America
Documentserial
Lang.English
Mediadigital; on-line
File formatpdf
ProvinceOntario; Quebec; Manitoba
NTS31; 32; 33; 34; 41; 42; 43; 44; 52; 53; 54
Lat/Long WENS-100.0000 -68.0000 60.0000 44.0000
Subjectstectonics; Archean; plate tectonics; terranes; subduction; modelling; rifting; magmas; Superior craton; disaggregation; Precambrian
Illustrationsgeological sketch map
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
Released2014 11 01
AbstractThe southern and western Superior craton of Canada (SWSC) is widely considered to be a tectonic collage accreted from north to south by multiple coeval subduction zones. We propose an alternative non--plate tectonic scenario where SWSC continental fragments are not exotic but derived by partial disaggregation of a heterogeneous older (Superior I) craton in response to a mantle overturn event that started at ca. 2780 Ma. During overturn,radial mantle outflow stretched and disaggregated the lithosphere to create the concentric Neoarchean fabric of the Superior craton, the southern part of which (SWSC) broke up into ribbon continents separated by oceanic tracts. Neoarchean calc-alkaline magmas record interaction between plume-related magma and older crust. A change in the mantle flow field at ca. 2720 Ma caused southward drift of the Northern Superior cratonic block as a result of mantle traction on its lithospheric keel, and SWSC terranes accreted to its leading edge.
Summary(Plain Language Summary, not published)
A new tectonic model is proposed to explain the concentric structural pattern of the Superior Craton. We suggest that ascent and radial outflow of plumes associated with a mantle overturn event at ca 2780 Ma stretched and locally disaggregated an older Superior I craton. Where the older crust broke apart, basalt-dominated crust like the Abitibi formed, whereas older crustal ribbon continents were extensively remelted. At 2720 Ma, the flow pattern changed, and a deep-rooted northern block drifted south and reaccreted the disaggregated fragments.
GEOSCAN ID295155

 
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