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TitleHydrothermal alteration of fractured Carboniferous sedimentary rocks along the Cobequid Fault Zone, western Nova Scotia
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AuthorPe-Piper, G; Piper, D J W; Zhang, Y; Sangster, C
SourceGeological Survey of Canada, Open File 8102, 2017, 724 pages, https://doi.org/10.4095/299610
Year2017
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
File formatpdf
ProvinceNova Scotia
NTS11E/05; 11E/06; 11E/11; 11E/12; 21H/07; 21H/08; 21H/09; 21H/10
AreaCobequid Highlands; Parrsboro; West Advocate; West Moose River; Port Grenville; Fox River; Wharton; Cape Chignecto
Lat/Long WENS -65.0000 -63.0000 45.6667 45.2500
Subjectstectonics; igneous and metamorphic petrology; mineralogy; geochemistry; mineral deposits; ore mineral genesis; metals; iron; copper; zinc; bedrock geology; lithology; host rocks; sedimentary rocks; sandstones; shales; igneous rocks; intrusive rocks; granites; plutons; hydrothermal systems; mineralization; mineralization, primary; alteration; albitization; biotitization; carbonatization; supergene deposits; paragenesis; thermal analyses; thermal history; tectonic history; magmatism; intrusions; veins; emplacement; lamprophyres; mineral enrichment; allanite; calcite; sulphides; carbonates; magnetite; fluorine; chlorite; electron microscope analyses; thin section microscopy; electron probe analyses; spectrometric analyses; geochemical analyses; geothermometry; mineralogical analyses; analytical methods; Avalon Terrane; Meguma Terrane; Cobequid Fault Zone; Horton Group; Fountain Lake Group; Minas Fault Zone; South Mountain Batholith; Cape Chigneto Pluton; West Moose River Pluton; North River Pluton; rare earth elements (REEs); REE mobility; scattered electron microscopic analyses; electron microprobe (SEM) analyses; Phanerozoic; Paleozoic; Carboniferous
Illustrationstables; geological sketch maps; photographs; photomicrographs; profiles; charts; histograms; binary plots
Released2017 02 15
AbstractThe Cobequid Fault Zone in northwestern Nova Scotia hosts the famous Londonderry iron deposit and smaller magnetite, base metal sulfide and barite deposits. The paragenetic sequence of hydrothermal veins cutting Tournaisian Horton Group sandstones and shales in the western part of the Cobequid Fault Zone was investigated from cross-cutting relationships in the field and from SEM backscattered electron images of polished thin sections. In hydrothermal veins in the Lynn Road area east of Parrsboro, the general paragenesis is: albite ± quartz ± chlorite ? biotite ? calcite ? pyrite and other sulfides ? supergene enrichment. Farther west, between Parrsboro and West Advocate, the general paragenesis is: quartz ± chlorite ? Fecarbonates, minor sulfides, calcite and synchysite ? supergene enrichment. Chlorite formation temperatures were higher at West Advocate (~215°C) than elsewhere (~165°C). In the area between Parrsboro and Lynn Road, 334 Ma lamprophyric subvolcanic intrusions include magmatic allanite, calcite and sulfides and these minerals are also found in veins in the Lynn Road area. Widespread veins of Fe-carbonates, magnetite and sulfides (Fe, Cu, Zn) were emplaced at ~323 Ma and were subsequently enriched by supergene alteration. Hydrothermal REE minerals in sedimentary host rocks are quite different from those in adjacent granite plutons, suggesting the importance of local derivation of REE and the role of fluorine in REE mobility in igneous rocks.
Summary(Plain Language Summary, not published)
The study investigates the sequence of hydrothermal veins developed in Lower Carboniferous sedimentary rocks along the Cobequid Fault Zone and relates them to regional igneous, tectonic and mineralizing processes. It compares the development of Rare Earth minerals in veins in sandstones with those in nearby granites.
GEOSCAN ID299610