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Rocks assigned to the Labrador Group record deposition during initial phases of the lower Paleozoic transgression onto the eastern continental margin of North America during late Early Cambrian time. In Labrador the group comprises two formations; the lower one, the Bradore Formation, is a series of conglomerates, sandstones, and minor siltstones; the upper one, the Forteau Formation, is a series of siltstones, shales, fossiliferous limestones, and reefs.
The Bradore Formation, interpreted on the basis of physical sedimentary structures to be a series of tidal-dominated, nearshore, sand shoals, is almost devoid of body fossils. The presence of an abundant soft-bodied infauna is, however, demonstrated by prolific Skolithos as well as numerous Monocraterion and Dolopichnus and minor forms such as Lingulichnus, Stipsellus, and Cruziana.
The Forteau Formation comprises a series of patch reefs rich in archaeocyathids surrounded and buried by interreef skeletal limestones, siltstones, and shales. In contrast to the underlying Bradore, these rocks are extremely rich in body fossils. Correspondingly, the interreef beds are replete with ichnofossils including Chondrites, Cylindrichnus, Monocraterion, Monomorphichnus, Paleophycus, Planolites, Rusophycus, Skolithos, and Teichichnus. These forms suggest that the environment of deposition was relatively shallow and that sedimentation was slow and continuous.
We have also discovered numerous traces in the fine-grained sediments which floor growth cavities within the reefs, suggesting that mobile organisms either inhabited the cavities or at least were transient through them.
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