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TitleReactivation of the Eastern Highlands Shear Zone, Cape Breton Island, Appalachian Orogen
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AuthorPiette-Lauzière, N; Graziani, R; Larson, K P; Kellett, D A
SourceTargeted Geoscience Initiative: 2018 report of activities; by Rogers, N (ed.); Geological Survey of Canada, Open File 8549, 2019 p. 295-305, https://doi.org/10.4095/313663 (Open Access)
Year2019
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Rogers, N; (2019). Targeted Geoscience Initiative: 2018 report of activities, Geological Survey of Canada, Open File 8549
File formatpdf
ProvinceNova Scotia
NTS11K/09; 11K/10
AreaCape Breton Island
Lat/Long WENS -60.6833 -60.4167 46.7500 46.5500
Subjectseconomic geology; tectonics; structural geology; geochronology; mineral deposits; mineral exploration; mineral potential; porphyry deposits; polymetallic ores; ore mineral genesis; ore controls; structural controls; bedrock geology; structural features; shear zones; faults; lithology; igneous rocks; intrusive rocks; granodiorites; granites; tonalites; diorites; metamorphic rocks; metasedimentary rocks; marbles; gneisses; sedimentary rocks; greywackes; psammites; volcanic rocks; rhyolites; tectonic history; deformation; metamorphism; orogenies; alteration; chloritization; kinematic analysis; radiometric dating; uranium lead dating; zircon dates; fabric analysis; garnet; Eastern Highlands Shear Zone; Bras-d'Or Terrane; Aspy Terrane; Ganderia; Avalonia; Acadian Orogeny; Neoacadian Orogeny; Roper Brook Diorite; Appalachian Orogeny; Chéticamp Gneiss; Salinic Orogeny; Wilkie Brook Shear Zone; Cameron Brook Granodiorite; Clyburn Brook Formation; Gisborne Flowage Diorite; ore systems approach; reactivation; meta-conglomerates; Phanerozoic; Paleozoic; Devonian; Silurian
Illustrationsgeoscientific sketch maps; geochronological charts; cross-sections; photographs; photomicrographs; Concordia diagrams; bar graphs; plots
ProgramKnowledge Management Coordination, Targeted Geoscience Initiative (TGI-5)
ProgramIntrusion/Porphyry ore systems - arc-related porphyry systems - time and space, Targeted Geoscience Initiative (TGI-5)
Released2019 03 01
AbstractThe Eastern Highlands shear zone (EHSZ), in the Cape Breton Island portion of Appalachian Orogen, records two ductile deformation events (D1 and D2) from Early Silurian to Late Devonian. The Devonian is a key period for the economic endowment of the orogen during which intrusion-related mineralization may be associated with active and/or reactivated regional shear zones. The EHSZ is, therefore, a key structure to characterize shear zone reactivation and assess how this may have localized ore-bearing intrusive rocks. To accomplish this, we have first focused on linking local deformation events to the regional kinematic framework. New U-Pb geochronology of zircon from de-formed specimens provide timing constraints on the two deformation events of the EHSZ. A rhyolite specimen with D1 fabrics and a granite dyke specimen affected by D2 deformation, both within the EHSZ, yielded weighted mean 206Pb/238U crystallization ages of 424 ± 4 Ma and 372 ± 4 Ma, respectively (2-sigma error). In addition, two foliated quartz-diorite specimens and a post-tectonic pegmatite specimen from the Chéticamp gneiss, west of the EHSZ, yielded weighted mean crystallization ages of 428 ± 9 Ma, 390 ± 8 Ma, and 391 ± 8 Ma, respectively. These new data constrain the EHSZ D1 to between ca. 424 and 390 Ma, likely during the Acadian Orogeny. The EHSZ was then reactivated (D2) after 372 Ma, which we attribute to the Neoacadian Orogeny. Considering the orientations and kinematics of the Neoacadian suture and the EHSZ, we interpret that the EHSZ was reactivated in a transpression-dominated environment.
GEOSCAN ID313663