The Cowichan fold and thrust system, Vancouver Island, southwestern British Columbia

Research Article| March 01, 1991 The Cowichan fold and thrust system, Vancouver Island, southwestern British Columbia T.D.J. ENGLAND; T.D.J. ENGLAND 1Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X5 Canada Search for other works by this author on: GSW Google Scholar T. J. CALON T. J. CALON 1Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X5 Canada Search for other works by this author on: GSW Google Scholar GSA Bulletin (1991) 103 (3): 336–362. https://doi.org/10.1130/0016-7606(1991)103<0336:TCFATS>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation T.D.J. ENGLAND, T. J. CALON; The Cowichan fold and thrust system, Vancouver Island, southwestern British Columbia. GSA Bulletin 1991;; 103 (3): 336–362. doi: https://doi.org/10.1130/0016-7606(1991)103<0336:TCFATS>2.3.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 The Cowichan fold and thrust system is a southwest-verging, linked thrust system formed by northeast-southwest, large-scale, crustal contraction involving the Upper Cretaceous Nanaimo Group and its Wrangellian basement. The geometry of the thrust system from plan and profile perspectives illustrates its thick-skinned structural style. The thrust system is interpreted to be a leading imbricate fan. Thrusting was most likely in sequence, creating an estimated minimum 20%-30% shortening at the basement/cover interface. Both fault-propagation and fault-bend folding are evident, the former being more common. Kinematic indicators and the geometry of the thrust system show no evidence of significant transpressional or transtensional displacement fields. Contraction postdates deposition of the Nanaimo Group and is indirectly dated as late Eocene.The sole fault of the thrust system is interpreted to rise from northwest to southeast on a series of deep lateral to oblique ramps and merge with the San Juan fault system. This explains the rapidly westward-thickening wedge of thrusted Wrangellian basement in the study area. In the east, the sole fault is interpreted to have locally permitted the Nanaimo Group to overthrust the San Juan Terrane. Investigation of the Cowichan fold and thrust system reveals how shortening during westward-progressing terrane accretion is accommodated in a forearc region dominated by a large slab of rigid, semicontinental crust. 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.