Jill‑Annette Marcotte

B. Sc. Honours Thesis

Regional Mapping and Petrographic Study of a Silurian Gneissic Complex, Belle Cote Road, Cape Breton, Nova Scotia

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The Leblanc Lake area is located in the central Cape Breton
Highlands south of the Cheticamp River. The main study area is
situated along Belle Cote Road, one of the numerous logging roads
in the region. Mapping at 1:10,000 scale revealed three
distincts units. From west to east these are the George Brook
amphibolite, a variably deformed amphibolite-garnet amphibolite
with local calc-silicate bands, most likely representing synvolcanic
intrusions, the Corney Brook schist, which is a medium
to high grade porphyroblastic schist (the high grade equivalent
of the Faribault Brook metasedimentary rocks), and the Belle Cote
Road gneiss, an Ordovician to Silurian tonalitic to granodioritic
orthogneiss.

Based on field relations, petrography, and structure, the
Belle Cote Road gneiss appears to be intrusive into the
metasedimentary and metavolcanic rocks of the Jumping Brook
metamorphic suite. This is contrary to the belief of some that
the Belle Cote Road gneiss was unconformably overlain by
the Jumping Brook metamorphic suite. It can be concluded that the
orthogneiss may well represent simply deformed plutonic rocks, in
which intrusion and deformation were syn-tectonic with respect to
each other.

Metamorphic grade increases toward the orthogneiss from all
directions in the area, including the Jumping Brook metamorphic
suite which has been interpreted as having formed in an island
arc setting (Connors, 1986). This strongly suggests that the
thermal anomaly causing metamorphism was associated with the
intrusion.
 

Keywords:
Pages: 101
Supervisor: Becky Jamieson