Abstract

Detailed studies of scattered outcrops and small quarries in the interior of northern New Brunswick have revealed the presence of small stromatoporoidal–stromatolitic reefs in a unit informally named the Laplante unit, of Pridolian age. The reefs consist mainly of laminar stromatoporoids and stromatolitic algae in a boundstone framework, but these are associated with tabulate coral bafflestones and also with stromatolitic algae, mudstones, and extensive biogenic and polymict breccias. The characteristics of the faunas and sediments suggest deposition as small reef mounds in relatively low-energy environments, and the associated internal breccias and mass flows suggest that these reef mounds were deposited on the upper slope at the margin of a narrow shelf, probably in a compressional tectonic regime with associated uplift. Several facies in the Laplante unit are similar to the Colline Daniel Facies of the West Point reef complex in southern Gaspé and suggest the possibility of a reef belt with sporadically developed reef mounds extending beneath Chaleur Bay. The reefal sediments are presently located in the basin between the Elmtree Inlier to the north and the Mirimichi Massif to the south, but there is some evidence that they are allochthonous. If so, they have not been transported very far. Evidence also suggests that emergence occurred and caused the development of solution features not long after deposition. This emergence was probably related to the phase of Pridolian tectonic compression and uplift.

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