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TitleStructural evolution of the Thetford Mines Ophiolite Complex, Canada: implications for the southern Québec ophiolitic belt
AuthorSchroetter, J -M; Bédard, J H; Tremblay, A
SourceTectonics vol. 24, no. 1, TC1001, 2005, 20 pages, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 2005286
Mediapaper; on-line; digital
File formatpdf
NTS21E/04; 21E/05; 21E/06; 21E/10; 21E/11; 21E/12; 21E/13; 21E/14; 21E/15; 21L; 31H/01; 31H/02; 31H/03; 31H/06; 31H/07; 31H/08; 31H/09; 31H/10; 31H/11; 31H/14; 31H/15; 31H/16; 31I/01; 31I/02; 31I/08
AreaChaudière River; St. Lawrence River; Saint-François River; Coleraine; Asbestos; Saint-Élie-de-Brompton; Mont Adstock; Thetford Mines; Mont Ham; Mont Caribou; Nadeau Hill; Breeches Lake; Back Lake; Disraeli; Lac Brompton; Mont Chauve; Monjoie Lake; Mont Orford; Eastman
Lat/Long WENS -73.5000 -70.0000 47.0000 45.0000
Subjectsstructural geology; tectonics; igneous and metamorphic petrology; ophiolites; igneous rocks; volcanic rocks; metamorphic rocks; sedimentary rocks; structural features; faults; granites; sediments; slates; limestones; sandstones; conglomerates; mudstones; siltstones; basalts; quartzites; phyllites; olistostromes; schists; faults, normal; obduction; ultramafic rocks; intrusions; dykes; faults, extension; sea floor spreading; subduction zones; basins; metamorphic zones; continental margins; aureoles; emplacement; folds; faults, thrust; faults, reverse; tectonic history; oceanic lithosphere; anticlines; synclines; deformation; flysch; tuffs; plutonic rocks; facies; dunites; pyroxenites; gabbros; diabases; harzburgites; mantle; amphibolites; lavas; breccias; turbidites; tectonites; foliation; fracturing; metasedimentary rocks; serpentinites; bedding; schistosity; cleavage; garnet; peridotites; chromitites; models; kinematic analysis; magmatic arcs; lithology; geochemical analyses; Southern Quebec ophiolitic belt; Thetford Mines Ophiolite Complex; Asbestos Ophiolitic Complex; Mont Orford Ophiolitic Complex; Dunnage Zone; Magog Group; Ascot Complex; St-Daniel Melange; Humber Zone; Sutton-Bennett Schists; Appalachian Orogen; Notre-Dame mountains anticlinorium; Sutton mountains anticlinorium; Brome Fault; Saint-Joseph Fault; Bennett Fault; La Guadeloupe Fault; Logan's Line; Taconian Orogen; Beauceville Formation; Saint-Victor Formation; Rosaire Group; Caldwell Group; Bennett Schists; Becancour Anticline; Carineault Anticline; Acadian Orogeny; Coleraine breccias; Thetford Mine massif; Adstock-Ham massif; Reed-Bélanger Mine; Nadeau Mine; Normandie Mine; Beaver Mine; American Chrome Mine; Jeffrey Mine; Lac Brompton Massif; Mont-Chauve Massif; Mont-Orford-Mont-Chagnon Massif; Sutton Schists; Mont-Adstock-Mont-Ham massif; Laurentian Margin; Phanerozoic; Paleozoic; Carboniferous; Devonian; Silurian; Ordovician; Cambrian
Illustrationsgeological sketch maps; location maps; schematic diagrams; sketches; photographs; cross-sections; models
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
ProgramValorisation-Recherche Québec, Diversification de l'exploration minérale au Québec
Released2005 01 11
AbstractThe Thetford Mines Ophiolite Complex (TMOC) preserves a complete ophiolitic sequence, and occupies the hanging wall of a major SE dipping normal fault, the Saint-Joseph fault. Preobduction, synobduction, and postobduction structures can be recognized in the TMOC. NS trending, preobduction, paleonormal faults are parallel to ultramafic minor intrusions, and to sheeted dykes, recording extension related to seafloor-spreading in a pericontinental suprasubduction zone basin. WNW trending synobduction, synmetamorphic fabrics are found toward the base of the TMOC and in the underlying continental margin rocks, but are absent in the upper part of the TMOC and overlying sedimentary rocks. These Ordovician (Taconian) structures record the development of a dynamothermal aureole immediately below the mantle/margin contact, and emplacement of the young ophiolite onto the continental margin. Postobduction structures include Late Silurian/Early Devonian, SE verging backthrusts and back folds that inverted the TMOC; and Middle Devonian (Acadian) NW verging folds and reverse faults. The tectonic history established for the TMOC is consistent with that of the adjacent Laurentian margin, and can be applied to the southern Québec ophiolitic belt as a whole. The structural synthesis of the ophiolitic belt, complemented with new observations and our compilation of stratigraphical, geochemical, geochronological, and petrological data, suggests that the southern Québec ophiolites may represent the remnants of the obduction of a single large slab of suprasubduction oceanic lithosphere extending for over a 100 km of strike length.

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