Abstract Along the western part of the Burlington Peninsula and in the Grand Lake region east of Corner Brook, high-grade metamorphic rocks, collectively referred to in the Burlington Peninsula as the "Fleur de Lys Supergroup," separate the Cambrian-Ordovician platform sedimentary rocks of western Newfoundland from the volcanic rocks and clastic sedimentary rocks of the Central mobile belt. The metamorphic rocks have a complex structural history, and are characterized by the presence of garnet and, in the Burlington Peninsula, staurolite and eclogite. In the Burlington Peninsula the metamorphic rocks are present as two units referred to as the western and eastern divisions of the Fleur de Lys Supergroup. In the Corner Brook region the metamorphic rocks include rocks of th Mount Musgrave Formation and associated gneiss and schist units.

On the east, the western division of the Fleur de Lys Supergroup and the gneissic rocks east of Corner Brook are in fault contact with low-grade metamorphosed volcanic and sedimentary rocks of the Baie Verte Group and Glover Formation, respectively. In the Burlington Peninsula, differences in the structural and metamorphic histories of the Fleur de Lys Supergroup and the Baie Verte Group suggest that the latter unit, if it is to be considered autochthonous, was deposited unconformably on the former. Correlation of the Baie Verte Group with the early Ordovician Snooks Arm Group of the Notre Dame Bay region therefore would suggest that the rocks of the Fleur de Lys Supergroup were metamorphosed before or during early Ordovician time. The presence in the Fleur de Lys of a paraconglomerat with characteristics of a water-laid tillite possibly indicates that this unit is at least partly of "infra-Cambrian" age. Within the eastern division of the Fleur de Lys, the Mings Bight Group of psammites apparently is overlain conformably toward the south by a succession of mafic and silicic volcanic and sedimentary rocks divided into two units--the Pacquet Harbour and Grand Cove Groups. The Pacquet Harbour Group is composed predominantly of mafic metavolcanic rocks. Associated clastic metasedimentary rocks include metagraywacke containing lithic fragments of andesite, and quartz-plagioclase-microcline intergrowths. The latter minerals are also common in metasedimentary units of the Grand Cove Group, which is composed predominantly of silicic metavolcanic rocks. The Pacquet Harbour G oup is considered by most workers to be intruded by the Burlington Granodiorite and thus to be older than the Baie Verte Group, with which it formerly was included, because the latter unit contains a black slate conglomerate with clasts of hornblende-granodiorite similar to the Burlington Granodiorite.

On the west, the western division of the Fleur de Lys Supergroup is bounded by the White Bay fault zone. However, in the Corner Brook region, equivalents of the Mount Musgrave Formation, which conformably underlies the Cambrian-Ordovician platform sedimentary rocks of western Newfoundland, were considered by H. Lilly to be represented among the high-grade metamorphic rocks east of Corner Brook. If the high-grade metamorphic rocks of the Burlington Peninsula are assumed to be equivalent to those of the Corner Brook region, such an interpretation would support the suggestion of Neale and Nash that the Fleur de Lys Supergroup was metamorphosed during the Taconian orogeny, which in Newfoundland is considered to have taken place in Wilderness time. Such an age for the Fleur de Lys metamorp ism would be noteworthy because the apparently profound nature of the metamorphism contrasts with the mild effect of the Taconian orogeny in the Notre Dame Bay region as well as in the rest of the Appalachians. A Late Cambrian-pre-Llanvirnian age would suggest a correlation of the Fleur de Lys metamorphism and tectonism with those of the Moine-Dalradian of the British Isles, and thus would support the concept of continental drift. An early Ordovician age (post-Llanvirnian-pre-Caradocian) might imply that the orogenic event that caused the metamorphism of the Fleur de Lys and the Moine-Dalradian migrated laterally from east to west through time.