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TitlePetrology, chronology and sequence of vein systems: Systematic magmatic and hydrothermal history of a major intracontinental shear zone, Canadian Appalachians
AuthorPe-Piper, G; Piper, D J W; McFarlane, C R M; Sangster, C; Zhang, Y; Boucher, B
SourceLithos vol. 304-307, 2018 p. 298-310, https://doi.org/10.1016/j.lithos.2018.02.016
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20180087
PublisherElsevier BV
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNewfoundland and Labrador; New Brunswick; Nova Scotia; Prince Edward Island; Quebec
NTS1; 2; 3; 10; 11; 12; 13; 20; 21; 22; 30; 31
AreaCanadian Appalachians; Cobequid Highlands
Lat/Long WENS -84.0000 -51.0000 55.0000 33.0000
Subjectstectonics; igneous and metamorphic petrology; geochronology; economic geology; bedrock geology; structural features; shear zones; faults; fractures; lithology; igneous rocks; volcanic rocks; intrusive rocks; granites; gabbros; tectonic history; plate margins; magmatism; orogenies; intrusions; veins; plutons; volcanism; hydrothermal systems; mineralization; emplacement; paragenesis; faulting; fracturing; subduction; metasomatism; mantle; scanning electron microscope analyses; radiometric dating; uranium lead dating; mass spectrometer analysis; mineral deposits; mineral potential; basins; Appalachian Province; Cobequid Shear Zone; Alleghanian Orogeny; Laurentia; Minas Fault Zone; Rheic Ocean; Magdalen Basin; Avalon Terrane; Carolina Terrane; Meguma Terrane; Central Piedmont Shear Zone; Fountain Lake Group; Mabou group; Windsor Group; Horton Gropu; Cumberland Basin; New Annan Thrust; Wyvern Pluton; Wentworth Pluton; Folly Lake Gabbro; Rockland Brook Fault; Cobequid Fault; Portapique Fault; St. Mary's Graben; Kennetcook Basin; Pleasant Hills Pluton; West Moose River Pluton; Kirkhill Fault; Spicers Cove Fault; Cape Chignecto Pluton; iron-oxide-copper-gold (IOCG) deposits; extension; upwelling; Phanerozoic; Mesozoic; Paleozoic; Permian; Carboniferous; Devonian; Silurian; Ordovician; Cambrian; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; block diagrams; geochronological charts; photographs; photomicrographs; cartoons; Concordia diagrams; plots; schematic cross-sections
ProgramTargeted Geoscience Initiative (TGI-4)
Released2018 02 20
AbstractIntra-continental shear zones developed during continental collision may experience prolonged magmatism and mineralization. The Cobequid Shear Zone formed part of a NE-SW-trending, orogen-parallel shear system in the late Devonian-early Carboniferous, where syn-tectonic granite-gabbro plutons and volcanic rocks 4 km thick were progressively deformed. In late Carboniferous to Permian, Alleghanian collision of Africa with Laurentia formed the E-W trending Minas Fault Zone, reactivating parts of the Cobequid Shear Zone. The 50 Ma history of hydrothermal mineralization following pluton emplacement is difficult to resolve from field relationships of veins, but SEM study of thin sections provides clear detail on the sequence of mineralization. The general paragenesis is: albite±quartz±chlorite±monazite->biotite->calcite, allanite, pyrite-> Fe-carbonates, Fe-oxides, minor sulfides, calcite and synchysite. Chronology was determined from literature reports and new U-Pb LA-ICPMS dating of monazite and allanite in veins.
Vein mineralization was closely linked to magmatic events. Vein emplacement occurred preferentially during fault movement recognised from basin-margin inversion, as a result of fractures opening in the damage zone of master faults. The sequence of mineralization, from ca. 355 Ma riebeckite and albite veins to ca. 327 (-305?) Ma siderite-magnetite and sulfide mineralization, resembles Precambrian iron-oxide-copper-gold (IOCG) systems in the literature. The abundant magmatic Na, halogens and CO2 in veins and some magmatic bodies, characteristic of IOCG systems, were derived from the deeply subducted Rheic Ocean slab with little terrigenous sediment. Regional extension of the Magdalen Basin caused asthenospheric upwelling and melting of the previously metasomatized sub-continental lithospheric mantle. Crustal scale strike-slip faulting facilitated the rise of magmas, resulting in high heat flow driving an active hydrothermal system.
Summary(Plain Language Summary, not published)
This study dates and provides a genetic interpretation of mineralized veins along a major fault zone in Nova Scotia
GEOSCAN ID308313