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Protolith, Mineralogy, and Gold Distribution of Carbonate Rich Rocks of the Larder Lake Break at Misema River, Ontario

<p> The Larder Lake Break (LLB) is one of the structures controlling
the location of gold deposits in the Kirland Lake camp. This
intensly carbonated and often strongly foliated zone is part of the
Larder Lake Group as defined by Downs (1980). Protoliths at the LLB
are problematical.
Misema River is a well exposed occurrence of the LLB, showing
chlorite schist, pervasively fuchsite quartz carbonate and syenite dyke
material. It is divided into three sections. Section I samples
indicate an ultramafic protolith as suggested by Jensen Cation plots,
and the section is interpreted as komatiitic flow(s). Section II is
well foliated and shows both ultramafic and calc-alkalic components
which decrease and increase in intensity respectively away from the
section I-section II contact. Section II is interpreted as a polymodal
sediment. Section III is similar chemically and texturally to section
I, and is therefore a komatiitic flow(s).
The intrusion of syenite dykes into section I occurred after
initial carbonatization and defonnation of the flows and associated
sediments.
Radiochemical neutron activation analysis shows all but one
of the syenite dyke samples to contain greater than 10 ppb gold
whereas the other rock types averages approximately 2 ppb. A peak content of 64 ppb occurred at a dyke contact. The high gold contents
clearly originate from the syenite dykes, which also provide a heat
source for a second period of carbonatization. </p> / Thesis / Bachelor of Science (BSc)

Identiferoai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18350
Date05 1900
CreatorsHaskett, William
ContributorsCrocket, J.H., Geology
Source SetsMcMaster University
LanguageEnglish
Detected LanguageEnglish

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