U-Pb geochronology of the Raglan gabbro belt, Central Metasedimentary Belt, Ontario; implications for an ensialic marginal basin in the Grenville Orogen

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doi: 10.1139/e96-052
Authors:Pehrsson, Sally; Hanmer, Simon; van Breemen, Otto
Author Affiliations:Primary:
Geological Survey of Canada, Continental Geoscience Division, Ottawa, ON, Canada
Volume Title:Canadian Journal of Earth Sciences Revue Canadienne des Sciences de la Terre
Source:Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 33(5), p.691-702. Publisher: National Research Council of Canada, Ottawa, ON, Canada. ISSN: 0008-4077
Publication Date:1996
Note:In English with French summary. Geol. Surv. Can., Contrib. No. 22095. 57 refs.; illus., incl. 1 table, geol. sketch map
Summary:Zircon crystallization ages for three plutons in the Raglan gabbro belt, in the hanging wall adjacent to the boundary thrust zone of the Central Metasedimentary belt, fall in the range 1246-1227 m.y., and a fourth gave a minimum age of ∼ 1175 m.y. These results allow a common origin for the gabbros, and the possibility that they may have constituted a rheologically stiff unit that controlled the localization of the top of the boundary thrust zone. They also allow that the Raglan gabbro belt may have been related to the later stages of development of a back-arc marginal basin, developed within the Elzevir terrain of the Central Metasedimentary belt. Contact relationships of the gabbros imply that deformation and metamorphism had started in the marginal basin by 1230 m.y., at least 40 m.y. before the major thrusting represented by the ∼ 1190 m.y. event in the boundary thrust zone. Inherited 1440-1301 m.y. zircons in the gabbros favour an Andean-style marginal basin, as opposed to an island-arc model, for the evolution of the NW part of the Central Metasedimentary belt. [R.A.H.]
Subjects:Absolute age; Basins; Continental crust; Crust; Dates; Faults; Gabbros; Geochronology; Granitic layer; Grenvillian Orogeny; Igneous rocks; Intrusions; Marginal basins; Nesosilicates; Orogeny; Orthosilicates; Paleogeography; Plutonic rocks; Plutons; Precambrian; Proterozoic; SEM data; Shear zones; Silicates; Thrust faults; U/Pb; Upper Precambrian; Zircon; Zircon group; Canada; Canadian Shield; Central Metasedimentary Belt; Eastern Canada; Grenville Province; North America; Ontario; Raglan Belt
Coordinates:N445000 N454000 W0773000 W0782000
Abstract Numbers:97M/68
Record ID:1996056723
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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