Lawsonite blueschist in the northern Sierra Nevada, California

Research Article| January 01, 1980 Lawsonite blueschist in the northern Sierra Nevada, California R. A. Schweickert; R. A. Schweickert 1Department of Geological Sciences and Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar R. L. Armstrong; R. L. Armstrong 2Department of Geological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1W5, Canada Search for other works by this author on: GSW Google Scholar J. E. Harakal J. E. Harakal 2Department of Geological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1W5, Canada Search for other works by this author on: GSW Google Scholar Geology (1980) 8 (1): 27–31. https://doi.org/10.1130/0091-7613(1980)8<27:LBITNS>2.0.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation R. A. Schweickert, R. L. Armstrong, J. E. Harakal; Lawsonite blueschist in the northern Sierra Nevada, California. Geology 1980;; 8 (1): 27–31. doi: https://doi.org/10.1130/0091-7613(1980)8<27:LBITNS>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Lawsonite-bearing blueschist metamorphic rocks along the North Fork Yuba River in the northern Sierra Nevada consist of three lithologic types. Most abundant is quartz-muscovite phyllite that possibly originated as part of a chert and shale sequence. These rocks rarely contain blueschist minerals. Metavolcanic rocks including massive lava and volcanic breccia are second in abundance and are typified by fracture-filling growths of crossite. Rare metaclastic rocks contain abundant lawsonite and quartz and minor glaucophane.The rocks were deformed inhomogeneously in three principal phases. Blueschist metamorphic recrystallization accompanied the earliest deformation. The later structural events, possibly related to the Late Jurassic Nevadan orogeny, deformed the blueschist minerals. Despite uncertainty regarding time(s) of Ar loss, K-Ar dates indicate that the high-pressure metamorphism occurred before 174 m.y. B.P. and possibly before 190 m.y. B.P. (Bajocian time or earlier), during Andean-type magmatic arc activity in eastern California and western Nevada. The blueschist rocks provide the first direct evidence for pre-Franciscan subduction in the Sierra Nevada region. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.