Basement-cover relationships in southwest Newfoundland

• Main Author: Brown, Peter A.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1974
• Subjects: Newfoundland
• Online Access: https://research.library.mun.ca/9517/; https://research.library.mun.ca/9517/1/Brown_PeterA.pdf

In the Port aux Basques area five geological divisions are recognised. These are Cape Ray Complex, The Port aux Basques Complex, The Windsor Point Group, The Harbour Le Cou Group. The first two are separated by, and the third overlies a 1 km wide mylonite zone the Cape Ray Fault. The Harbour Le Cou and Bay du Nord Groups occur in the eastern part of the area and are deformed during the reworking of the Port aux Basques Complex. -- The Cape Ray Complex occurs to the west of the Cape Ray Fault Zone and comprises a chaotic, intensely retrogressed leucocratic gneiss intruded by granitic phases. The Windsor Point Group consists of a series of metasedimentary and metavolcanic rocks which unconformably overlie the Cape Ray Complex and the Cape Ray Fault Zone, and have been mildly deformed by late movements along the fault. -- The Port aux Basques Complex crops out to the east of the Cape Ray Fault Zone and comprises a well banded gneiss complex intruded by granitic phases. Between the fault and Isle aux Morts at least three periods of penetrative deformation are recognized. The earlier two phases are, at least in part, responsible for the development of the gneissic banding. The later phase subisoclinally folds this banding. The highest grade of metamorphism is associated with the second event and resulted in the development of garnet, staurolite, kyanite, sillimanite, and potassium feldspar. The Port aux Basques granite intruded the gneiss in post D1 - pre D2 times. -- East of Isle aux Morts the gneisses are reworked i.e., further deformed and metamorphosed. These deformations, three are recognized, overprint the gneissic fabrics and result in the development, from west to east, of shear zones, recumbent folds, and tectonic slides. During the earliest event, which is the most penetrative, the gneisses were reconstituted to a finely schistose rock such that no lithological boundary was apparent between the gneisses and a sequence of pelitic to semi-pelitic rocks, the Harbour Le Cou Group, infolded, by this event, into ...