Abstract

More than 100 m of nearly flat-lying, fluvially derived, thick-bedded and lensoid, clast-supported conglomerate and sandstone are found on Red Island, off the coast of the Port au Port Peninsula, western Newfoundland. Formally described herein and named Red Island Road Formation, the strata represent a unique lithologic formation not exposed or known anywhere else in the region. Characteristic features include abundant, rounded, highly weathered and varnished cobbles and boulders derived from an unknown mixed volcanic and very low to low-grade metamorphic terrane. Although the unit is largely unfossiliferous, a thin sandstone bed near the top of the type section contains primitive dichotomously branched plant remains and biostratigraphically significant palynomorphs. Among more than 25 species of spores, it is the diversity of Emphanisporites, Dictyotriletes, and Dibolisporites, and in particular Dibolisporites echinaceus, Dictyotriletes canadensis, Emphanisporites annulatus, E. erraticus, and E. schultzii that indicate the Red Island Road Formation was deposited during the early and early late Emsian Emphanisporites annulatusCamarozonotriletes sextantii Assemblage Zone. Biostratigraphy places age constraints on Acadian tectonism, local thrusting, and foreland basin development in this part of the Anticosti Basin. The suite of clasts indicates a radical shift in provenance as compared with siliciclastic units lower in the foreland basin sequence. Clearly, the source for these clasts is not local. Terranes farther afield, such as the La Poile Group in southwestern Newfoundland, should be examined as possibilities for the provenance of these rocks.

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