Multiple sediment incorporation events in a continental magmatic arc: Insight from the metasedimentary rocks of the northern North Cascades, Washington (USA)

Simple item page
dc.contributor.authorHanson, Ann E. H.en
dc.contributor.authorGordon, Stacie M.en
dc.contributor.authorAshley, Kyle T.en
dc.contributor.authorMiller, Robert B.en
dc.contributor.authorLangdon-Lassagne, Elizabethen
dc.coverage.countryUnited Statesen
dc.coverage.stateWashingtonen
dc.date.accessioned2022-08-03T19:33:52Zen
dc.date.available2022-08-03T19:33:52Zen
dc.date.issued2022-02en
dc.description.abstractThe rheology and composition of arc crust and the overall evolution of continental magmatic arcs can be affected by sediment incorporation events. The exhumed Cretaceous-Eocene North Cascades arc exposes abundant meta-sedimentary rocks that were incorporated into the arc during multiple events. This study uses field relationships, detrital zircon geochronology, bulk rock geo-chemistry, geothermometry, and quartz-in-garnet geobarometry to distinguish approximate contacts and emplacement depths for different metasedimentary units to better understand their protolith incorporation history and impact on the arc. The Skagit Gneiss Complex is one of the main deep crustal units of the North Cascades arc. It includes metasedimentary rocks with distinct detrital zircon signatures: Proterozoic-Cretaceous (Group 1) or Triassic-Cretaceous (Group 2) zircon populations. Both metasedimentary groups achieved near-peak metamorphic conditions of 640-800 degrees C and 5.5-7.9 kbar; several Group 2 samples reveal the higher pressures. A third group of meta sedimentary rocks, which was previously interpreted as metamorphosed equivalents of backarc sediments (Group 3), exhibited unimodal Triassic or bimodal Late Jurassic- Early Cretaceous detrital zircon signatures and achieved near-peak conditions of 570-700 degrees C and 8.7-10.5 kbar. The combined field and analytical data indi-cate that protoliths of Group 1 and Group 2 metasedimentary rocks were successively deposited in a forearc basin and underthrusted into the arc as a relatively coherent body. Group 3 backarc sediments were incorporated into the arc along a transpressional step-over zone. The incorporation of both forearc and backarc sediments was likely facilitated by arc magmatism that weakened arc crust in combination with regional transpression.en
dc.description.notesWe thank Joel DesOrmeau for assistance in sample preparation, obtaining mineral energy-dispersive detector and zircon-cathodoluminescence images, and U-Pb measurements at the University of Nevada, Reno. We also thank Andrew Kylander-Clark for help with U-Pb measurements at the University of California, Santa Barbara; Anette von der Handt of the University of Minnesota and Nick Botto of the University of California, Davis, for assistance with electron probe microanalyzer data collection; Jade Star Lackey and Jonathan Harris of Pomona College for help with wholerock geochemical measurements; and Stephen Hanson for assisting in the field. We also thank William Matthews and an anonymous reviewer, Associate Editor Craig Jones, and Science Editor David Fastovsky for their helpful comments on this manuscript. This research was funded by National Science Foundation Grant EAR-1419810 to S.M. Gordon and EAR-1419787 to R.B. Miller, U.S. Geological Survey EDMAP grant G19AC00219 to S.M. Gordon, and a Geological Society of America Graduate Student Research grant to A.E.H. Hanson.en
dc.description.sponsorshipNational Science Foundation [EAR-1419810, EAR-1419787]; U.S. Geological Survey EDMAP [G19AC00219]; Geological Society of America Graduate Student Research granten
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1130/GES02425.1en
dc.identifier.issue1en
dc.identifier.urihttp://hdl.handle.net/10919/111440en
dc.identifier.volume18en
dc.language.isoenen
dc.publisherGeological Society of Americaen
dc.rightsCreative Commons Attribution-NonCommercial 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by-nc/4.0/en
dc.subjectskagit gneiss complexen
dc.subjectcoast mountains batholithen
dc.subjectsan-juan islandsen
dc.subjectdetrital zircon provenanceen
dc.subjectross lake faulten
dc.subjectti-in-zirconen
dc.subjectu-th-pben
dc.subjectbritish-columbiaen
dc.subjectmethow basinen
dc.subjectdeep crusten
dc.titleMultiple sediment incorporation events in a continental magmatic arc: Insight from the metasedimentary rocks of the northern North Cascades, Washington (USA)en
dc.title.serialGeosphereen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
298.pdf
Size:
6.76 MB
Format:
Adobe Portable Document Format
Description:
Published version
Download

Collections

Scholarly Works, Geosciences