Anatomy and orogenic history of a Paleoproterozoic accretionary belt: the Makkovik Province, Labrador, Canada
The Makkovik Province is a segment of a Paleoproterozoic accretionary belt (the MakkovikKetilidian orogen) that developed on the southern margin of Laurentia at 1.91.7 Ga. In contrast to coeval Laurentian orogenic belts that mainly resulted from collision of Archean plates, MakkovikianKetilidian...
Published in: | Canadian Journal of Earth Sciences |
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Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
2002
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Subjects: | |
Online Access: | http://dx.doi.org/10.1139/e01-099 http://www.nrcresearchpress.com/doi/pdf/10.1139/e01-099 |
Summary: | The Makkovik Province is a segment of a Paleoproterozoic accretionary belt (the MakkovikKetilidian orogen) that developed on the southern margin of Laurentia at 1.91.7 Ga. In contrast to coeval Laurentian orogenic belts that mainly resulted from collision of Archean plates, MakkovikianKetilidian orogenesis was dominated by active-margin processes including continental margin arc plutonism and juvenile terrane accretion, both of which were accompanied by regional transpression. In the Makkovik Province, earliest deformation and amphibolite-facies metamorphism of Paleoproterozoic riftdrift assemblages (Post Hill and Moran Lake groups) and the Archean foreland (Nain Province) occurred at 1.9 Ga in response to accretion of a Paleoproterozoic island arc. Following this collision, cratonward-dipping subduction was established, resulting in the formation of the 18951870 Ma Island Harbour Bay Plutonic Suite, a calc-alkaline magmatic arc built on reworked Archean crust. Crust formation continued between ca. 1860 and 1850 Ma with deposition of the Aillik Group on a largely juvenile basement in a rifted-arc or back-arc setting. Sometime before 1802 Ma this depositional basin was tectonically inverted, with resultant northwestward thrusting of the Aillik Group over reworked Archean crust. This phase of deformation may have been driven by accretion of a second island arc potentially represented by the Cape Harrison Metamorphic Suite. Regional transpression and amphibolite-facies metamorphism at ca. 18151780 Ma were accompanied by widespread granitoid plutonism. These events were mainly concentrated in the juvenile domains and are thought to reflect processes in a broad continental back-arc setting. A final orogenic pulse, marked by regional greenschist-facies transpression and emplacement of A-type granitoid plutons, occurred between 1740 and 1700 Ma, with deformation and plutonism potentially linked to crustmantle detachment and incursion of mafic magmas at the base of the crust, respectively. The record of crustal ... |
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