Collisional Snowbird tectonic zone resurrected; growth of Laurentia during the 1.9 Ga accretionary phase of the Hudsonian Orogeny

The ∼2800-km-long Snowbird tectonic zone is one of the most controversial tectonic features of the Canadian shield. Metamorphic and in situ geochronologic data reported here reveal that a 1.9 Ga medium- to high-pressure belt extends along most of this tectonic zone. In contrast to recent interpretat...

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Bibliographic Details
Published in:Geology (Boulder) 2007-10, Vol.35 (10), p.911-914
Main Authors: Berman, R. G, Davis, W. J, Pehrsson, S
Format: Article
Language:English
Subjects:
absolute age
accretion
Canada
Canadian Shield
Churchill Province
crustal thickening
dates
Diamonds
experimental studies
Fracture zones
Geochronology
geologic barometry
geologic thermometry
Geological time
Hudsonian Orogeny
ion probe data
Laurentia
mass spectra
metamorphic belts
Metamorphic rocks
metamorphism
microcontinents
monazite
North America
Nunavut
orogenic belts
orogeny
P-T conditions
phosphates
plate collision
Plate tectonics
Precambrian
Proterozoic
Rock deformation
SHRIMP data
Snowbird tectonic zone
spectra
Structural geology
tectonics
upper Precambrian
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Summary:The ∼2800-km-long Snowbird tectonic zone is one of the most controversial tectonic features of the Canadian shield. Metamorphic and in situ geochronologic data reported here reveal that a 1.9 Ga medium- to high-pressure belt extends along most of this tectonic zone. In contrast to recent interpretations, a collisional origin is indicated by the length of this metamorphic belt, tectonic thickening documented in parts of it, geological contrasts across it, and subduction-type microdiamonds within it. This collisional event marks a pre-1.865 Ga phase of the Hudsonian orogeny involving microcontinent accretion that was fundamental to the growth of Laurentia.
ISSN:0091-7613
1943-2682
DOI:10.1130/G23771A.1