Geochemical and isotopic investigation of magmatism in the Fox River belt: tectonic and economic implications

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dc.contributor.authorDesharnais, Guy
dc.contributor.examiningcommitteePeck, Dave (Anglo-American Exploration Ltd.)en_US
dc.contributor.supervisorHalden, Norman (Geological Sciences)en_US
dc.date.accessioned2012-09-05T15:35:04Z
dc.date.available2012-09-05T15:35:04Z
dc.date.issued2012-09-05
dc.degree.disciplineGeological Sciencesen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractThe Fox River Belt forms a segment of the Circum-Superior Belt that comprises a series of ca. 1900 Ma volcanosedimentary belts located around the margins of the Superior Province. The Fox River Belt is a north-facing homoclinal sequence, composed of a rift-related sedimentary sequence, intercalated with thick sequences of komatiites and tholeiites, and intruded by mafic-ultramafic intrusions. Geological mapping, whole rock geochemistry and S, Nd- and Hf-isotope geochemistry of the magmatic and sedimentary units within the belt were used to obtain a better understanding of the magmatic and tectonic history of the belt and its relation with other segments of the Circum-Superior Belt. The compositional variation observed in the volcanic rocks (19% to 5% MgO) can be accounted for as the product of fractional crystallization. Trace element patterns as well as εNd and εHf values (-4 to +8 and +4 to +18 respectively) indicate that the magmatism within the belt was the product of partial melting of depleted mantle that was locally contaminated with sediments or gneiss. A plume origin for this melting event is proposed based on the high degree of partial melting, the large volume of magma, and the presence of a radiating dyke swarm. The 250 km long Fox River Sill appears to have behaved as a magma conduit during part of its history. Several intervals within the sill show enrichment and depletion of PGE. The KO Zone PGE-Cu-Ni mineralization (up to 5ppm PGE) formed from magmatic sulphides whose tenor was upgraded by the upward percolation of evolved intercumulus magma. Contaminated Lower Intrusions and the lower margin of the Fox River Sill are considered particularly prospective for hosting Ni- Cu-PGE mineralization.en_US
dc.description.noteOctober 2005en_US
dc.identifier.urihttp://hdl.handle.net/1993/8597
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectMagmatismen_US
dc.subjectGeochemistryen_US
dc.subjectCircum-Superioren_US
dc.subjectBelten_US
dc.subjectIsotopicen_US
dc.titleGeochemical and isotopic investigation of magmatism in the Fox River belt: tectonic and economic implicationsen_US
dc.typedoctoral thesisen_US
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