<p> intrusive Ultramafic sill of the Cape Smith-Wakeham Bay Fold
Belt, located in the Ungava Peninsula P.Q., was studied. Measurements
of olivine crystals were made on enlarged images of thin sections to
determine the average olivine grain size and volume across the intrusion. </p> <p> The Bravo ultramafic sills exhibit a peculiar petrographic and
chemical zoning, the rocks becoming increasingly rich in olivine as one
moves toward the centre of the intrusion. Rock Compositions range from
gabbro at the margin to olivine rich peridotite near the centre. The
olivine grain size distribution exhibits n similar zoning, the grain
size increasing toward the centre. However, the maximum value is skewed somewhat to the south along the edge of the central olivine rich zone,
coinciding with the maximum value of Ns (Nickel in sulfides). </p> <p> The zoning is a consequence of flowage differentiation. Along
the margins of the intrusion grain dispersive pressure (the pressure due
to mechanical interaction between phenocrysts is dominant and grains
are forced toward the centre. Within the centre of the intrusion, where
the increased crystal concentration results in plug flow, the force of
gravity is dominant and the largest grains make their way to the base
of the plug. </p> <p> The Bravo Ultramafic Sills are pre-tectonic in origin being intruded into a group of eugeosynclinal strata in a sub-horizontal
attitude. </p> / Thesis / Bachelor of Science (BSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20920 |
| Date | 04 1900 |
| Creators | Thompson, Danny |
| Contributors | Clifford, P. M., Geology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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