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Sediment underthrusting within a continental magmatic arc: Coast Mountains batholith, British Columbia

Though continental magmatic arcs are factories for new continental crust, a significant proportion of continental arc magmas are recycled from supracrustal material. To evaluate the relative contributions of retroarc underthrusting and trench side partial sediment subduction for introducing supracrustal rocks to the middle and lower crust of continental magmatic arcs, we present results from the deeply exposed country rocks of the Coast Mountains batholith of western British Columbia. Prior work demonstrates that these rocks underwent widespread partial melting that contributed to the Coast Mountains batholith. We utilize U-Pb zircon geochronology, Sm-Nd thermochronology, and field-based studies to document the protoliths and early burial history of amphibolite and granulite-facies metasedimentary rocks in the Central Gneiss Complex. U-Pb detrital zircon data from the structurally highest sample localities yielded similar to 190Ma unimodal age peaks and suggest that retroarc rocks of the Stikine terrane constitute a substantial portion of the Central Gneiss Complex. These supracrustal rocks underwent thrust-related burial and metamorphism at >25km depths prior to similar to 80Ma. These rocks may also be underlain at the deepest exposed structural levels by Upper Cretaceous metasedimentary rocks, which may have been emplaced as a result of trench side underplating or intraarc burial. These results further our understanding of the mechanisms of material transport within the continental lithosphere along Cordilleran subduction margins.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626287
Date10 1900
CreatorsPearson, David M., MacLeod, Douglas R., Ducea, Mihai N., Gehrels, George E., Jonathan Patchett, P.
ContributorsUniv Arizona, Dept Geosci, Department of Geosciences; Idaho State University; Pocatello Idaho USA, Department of Geosciences; Idaho State University; Pocatello Idaho USA, Department of Geosciences; University of Arizona; Tucson Arizona USA, Department of Geosciences; University of Arizona; Tucson Arizona USA, Department of Geosciences; University of Arizona; Tucson Arizona USA
PublisherAMER GEOPHYSICAL UNION
Source SetsUniversity of Arizona
LanguageEnglish
Detected LanguageEnglish
TypeArticle
Rights©2017. American Geophysical Union. All Rights Reserved.
Relationhttp://doi.wiley.com/10.1002/2017TC004594

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