Structure, timing, and model of emplacement of the Rose Blanche Granites, southwestern Newfoundland.
The Rose Blanche Granites are a suite of two-mica granites emplaced within amphibolite-grade metasediments of the Harbour Le Cou Group (Exploits subzone of the Dunnage Zone, Central Mobile Belt), in the Appalachians of SW Newfoundland. Regional D$\sb2$ is a result of oblique collision of the St. Law...
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| Format: | Thesis |
| Language: | unknown |
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Université d'Ottawa / University of Ottawa
1997
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| Online Access: | https://dx.doi.org/10.20381/ruor-16683 http://www.ruor.uottawa.ca/handle/10393/10153 |
| Summary: | The Rose Blanche Granites are a suite of two-mica granites emplaced within amphibolite-grade metasediments of the Harbour Le Cou Group (Exploits subzone of the Dunnage Zone, Central Mobile Belt), in the Appalachians of SW Newfoundland. Regional D$\sb2$ is a result of oblique collision of the St. Lawrence and Cabot promontories, while D$\sb3$ is a result of orogen-parallel transpression. Bedding and bedding sub-parallel S$\sb1$ in the Harbour Le Cou wall rocks has been transposed and overprinted by S$\sb2$--the dominant regional fabric which contains a well-developed stretching lineation L$\sb2.$ The Rose Blanche Granite suite consists of a multitude of cm- to km-scale sheets and dykes, which are both concordant with, and cut across S$\sb2,$ and include xenoliths with S$\sb2$ fabrics. Some of the larger plutons are demonstrably laccoliths, and often occur in association with anatectic migmatites. Anisotropy of Magnetic Susceptibility analysis was carried out for 34 sites collected from three large-scale intrusions. Dominantly low values of magnetic susceptibility $\rm(K\sb{m}\le200$ SI) indicate that in the majority of samples it is dominated by biotite, although in some, accessory amounts of ilmenite and late magnetite make a contribution. In the majority of samples the Anisotropy of Magnetic Susceptibility fabric represents an indirect estimation of biotite shape preferred orientation. Microstructures observed in the Rose Blanche Granites are indicative of solid-state, amphibolite-grade deformation. The data support the interpretation that the suite was intruded syn-D$\sb2,$ during peak metamorphic conditions. (Abstract shortened by UMI.) |
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