Karen Connors

B. Sc. Honours Thesis

Relations Between the Sulphide Minerals, Metamorphism, and Deformation in the Faribault Brook Area of the Cape Breton Highlands, Nova Scotia

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The study area is located within the Jumping Brook Complex which is part of the western Highlands volcanic sedimentary complex. In the Faribault Brook area, the Jumping Brook Complex consists of a unit of pillow basalts which is overlain by a sedimentary sequence with interbedded felsic volcanic layers near the base. The units have undergone upper greenschist to lower amphibolite facies metamorphism and polyphase deformation. The main fabric consists of a pervasive foliation and a later crenulation which locally dominates in the finer grained metasedimentary layers. Prograde metamorphism peaked late in the deformation, during or after the development of the crenulation.

Sulphide minerals are found throughout both the metavolcanic and metasedimentary units, but the main concentrations of base metal sulphides are associated with the felsic volcanic layers. The presence of the sulphide minerals prior to metamorphism and deformation is indicated by alignment parallel to the foliation and crenulation, metamorphic recrystallization, and brittle deformation of these minerals. Significant concentrations of sulphides are also associated with ductile shear zones, thus indicating that remobilization of the sulphide minerals has occurred. The presence of the sulphides prior to deformation and the association with the felsic volcanic layers suggests that the base metal deposits are syngenetic.

Discriminant diagrams of the geochemical data indicate that the pillow basalts may have formed in an island arc environment. The sequence of lithologies and field evidence support this type of environment. The presence of a syngenetic base metal deposit in an island arc sequence suggests that the sulphides may have formed as a volcanogenic exhalative deposit.

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Pages: 117
Supervisor: Rebecca Jamieson