Research Article| November 01, 1982 Petrologic, structural, and age relations of serpentinite, amphibolite, and blueschist in the Shuksan Suite of the Iron Mountain–Gee Point area, North Cascades, Washington E. H. BROWN; E. H. BROWN 1Department of Geology, Western Washington University, Bellingham, Washington 98225 Search for other works by this author on: GSW Google Scholar D. L. WILSON; D. L. WILSON 1Department of Geology, Western Washington University, Bellingham, Washington 98225 Search for other works by this author on: GSW Google Scholar RICHARD LEE ARMSTRONG; RICHARD LEE ARMSTRONG 2Department of Geological Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B4 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, Canada V6T 2B4 Search for other works by this author on: GSW Google Scholar Author and Article Information E. H. BROWN 1Department of Geology, Western Washington University, Bellingham, Washington 98225 D. L. WILSON 1Department of Geology, Western Washington University, Bellingham, Washington 98225 RICHARD LEE ARMSTRONG 2Department of Geological Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B4 J. E. HARAKAL 2Department of Geological Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B4 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1982) 93 (11): 1087–1098. https://doi.org/10.1130/0016-7606(1982)93<1087:PSAARO>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation E. H. BROWN, D. L. WILSON, RICHARD LEE ARMSTRONG, J. E. HARAKAL; Petrologic, structural, and age relations of serpentinite, amphibolite, and blueschist in the Shuksan Suite of the Iron Mountain–Gee Point area, North Cascades, Washington. GSA Bulletin 1982;; 93 (11): 1087–1098. doi: https://doi.org/10.1130/0016-7606(1982)93<1087:PSAARO>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 SocietyGSA Bulletin Search Advanced Search Abstract Part of the Shuksan blueschist terrane, near Iron Mountain and Gee Point, North Cascades, Washington, has associated serpentinite, amphibolite, barroisite schist, blueschist, rare eclogite, and blackwall-type metasomatic rock. Field, petrographic, and microprobe observations indicate that the amphibolite and barroisite schists were metamorphosed in contact with peridotite and suggest that the peridotite may have been a heat source. The serpentinite and associated rocks are structurally concordant with the regional blueschists and have been overprinted by blueschist metamorphism. Isotopic dating gives metamorphic ages of 148 ± 5 to 164 ± 6 m.y. for the amphibolite and barroisite schist and 129 ± 5 m.y. for nearby regional Shuksan blueschists. The origin of the serpentinite + amphibolite + blueschist assemblage is interpreted to be the result of sequential events in a subduction zone. As subduction began, oceanic crustal materials underwent high-temperature metamorphism along the hot ultramafic hanging wall and were converted to amphibolites; materials that were subducted later came in contact with a cooler hanging wall and recrystallized as blueschist. This hypothesis may be applicable to the origin of similar rock associations in the Franciscan terrane and other orogenic belts. 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.
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Brown et al. (1982) studied this question.