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Petrography and geochemistry of the McArthur Township area, Ontario /

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dc.contributor.author Tabatabai, Mehran. en_US
dc.date.accessioned 2009-06-15T17:00:39Z
dc.date.available 2009-06-15T17:00:39Z
dc.date.issued 1978-06-15T17:00:39Z
dc.identifier.uri http://hdl.handle.net/10464/1611
dc.description.abstract The McArthur Township area in the Archean Abitibi Belt of northeast Ontario contains northwesterly trending volcanic rocks which are located on a limb of a large syncline. The axial trace of the syncline passes through the adjacent Douglas Township. The Archean volcanic rocks and associated sedimentary rocks are intruded and deformed by two large plutons and a few smaller hypabyssal intrusions. A petrographic and geochemical study of the Precambrian rocks exposed 1n the study area was undertaken in order to investigate the metamorphic grade and geochemical characteristics of the rocks. All the samples were studied with the microscope and analysis of 20 major and trace elements were determined on a selection of the less altered specimens by x-ray fluorescence. Three different periods of igneous activity have occurred in the study area. The first two periods were dominated by volcanic extrusive rocks accompanied by gabbroic sills. The third cycle is the diapiric intrusion of the granitic plutons and subsequent metamorphism of the older rocks to the low to medium grade. Two periods of sedimentation are also recognized in the study area which occurred after the first and second cycle of volcanism. Chemically, the lavas are subdivided into three main associations: (1) The komatiitic association is characterized by high MgO, high Ni, low Ti02 and a low FeO*/(FeO* + MgO) ratio. They occupy the base of each volcanic cycle and some of the flows exhibit spinifex textures. (2) The tholeiitic association displays distinct iron and titanium enrichment trends in the intermediate membersor -i r (3) The calc-alkaline association contains low FeO* and TI02 and high Ni contents relative to modern calc-alkaline types. They are formed at the end of each cycle of volcanism and overlie the tholeiitic flows. All three associations of the first volcanic cycle are exposed in the study area, while the second cycle is represented by a komatiltic sequence. The volcanic rocks were possibly formed by multiple partial melting of the Archean mantle to produce parental magmas under various P - T conditions. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Petrology en_US
dc.subject Geochemistry en_US
dc.title Petrography and geochemistry of the McArthur Township area, Ontario / en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Earth Sciences en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Earth Sciences en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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