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Structural history of ophiolite obduction, Bay of Islands, Newfoundland

1993; Geological Society of America; Volume: 105; Issue: 3 Linguagem: Inglês

10.1130/0016-7606(1993)105 2.3.co;2

1943-2674

G. Suhr, Peter A. Cawood,

High-pressure geophysics and materials

Research Article| March 01, 1993 Structural history of ophiolite obduction, Bay of Islands, Newfoundland GÜNTER SUHR; GÜNTER SUHR 1Centre for Earth Resources Research, Department of Earth Sciences, Memorial University, St. John's, Newfoundland, Canada, A1B 3X5 Search for other works by this author on: GSW Google Scholar PETER A. CAWOOD PETER A. CAWOOD 1Centre for Earth Resources Research, Department of Earth Sciences, Memorial University, St. John's, Newfoundland, Canada, A1B 3X5 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1993) 105 (3): 399–410. https://doi.org/10.1130/0016-7606(1993)105 2.3.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 GÜNTER SUHR, PETER A. CAWOOD; Structural history of ophiolite obduction, Bay of Islands, Newfoundland. GSA Bulletin 1993;; 105 (3): 399–410. doi: https://doi.org/10.1130/0016-7606(1993)105 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 Obduction-related structures in the ophiolitic Bay of Islands Complex, west Newfoundland, are classified into shearing dominated and accretion dominated. Mapping of these structures is combined with other geological constraints and provides the basis for a reconstruction of the obduction history of the ophiolite. The earliest detachment structures are shearing dominated and are preserved in the basal peridotites. They indicate north-directed thrusting. Detachment was facilitated by the shallow position of the lithosphere-asthenosphere boundary below the recently extinct Bay of Islands spreading ridge. Detachment involved lithosphere of the southern side and immediate northern side of the ridge. During the early stages of detachment, the Coastal Complex, an arc-related unit located to the west of the Bay of Islands Complex, acted largely as a lateral ramp to obduction. Early accretion occurred in two tectonic situations: (1) at the stage when the basal décollement plane intersected the boundary to the structurally and lithologically diverse Coastal Complex; this resulted in accretion of blocks up to several hundred meters thick with a lithological make-up not known from the Bay of Islands Complex; and (2) at the stage when the basal thrust plane intersected the oceanic crust. Deformation switched into the mafic and hydrated footwall lithologles and led to intermittent accretion of mafic oceanic crustal rocks now preserved in the metamorphic sole. Only the Lewis Hills massif, located close to the Coastal Complex during detachment, preserves evidence for both types of early accretion. At a later stage of obduction, localized removal of the basal sequence of the ophiolite was associated with accretion of a diverse assemblage of harzburgites, amphibolites, and greenschists. 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.