Abstract

Sedimentological and geophysical studies of the surficial geology of the Labrador Shelf reveal evidence of sediment provenance and modern seabed dynamics. Analyses of lithic fragments of grab samples from southern Saglek Bank and Makkovik Bank indicate that a high proportion of the surficial cover is of ice-rafted origin. Fossilferous carbonate fragments of Paleozoic age suggest a northern Greenland or Arctic island provenance. Heavy-mineral analyses reveal minerals common to igneous and high-grade metamorphic rocks. The Precambrian terrains of Labrador are a possible early sediment source, although similar more northerly terrains could be more recent sources.The geologic environments of Saglek and Makkovik banks differ, as shown by sediment textures and the distribution and form of ice scours that are abundant over the Labrador Shelf. The contrasting environments result largely from differing degrees of postglacial sediment reworking, evidenced by mineral hydraulic equivalence of the sand fractions from both banks. Sediments on the Makkovik Bank undergo present-day transport as a result of a strong hydrodynamic regime. The deeper, broader Saglek Bank is a hydrodynamically quiet zone except near the seaward bank margin, where strong sediment reworking by currents has and is presently taking place.

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