Tectonostratigraphic evolution of the Labrador margin, Atlantic Canada

The Labrador continental margin provides a rich source of data with which to study the relationships between stratigraphy, tectonics and paleoenvironment. We have completed a regional seismic interpretation and integrated this with new biostratigraphic data, based on analyses of palynomorphs from wells in the Hopedale and Saglek Basins which occur on this margin. Our results are summarized in a tectonostratigraphic chart, which displays new and consistent age control for the major lithostratigraphic units and provides more precise evaluation of their depositional and paleoenvironmental history. We have identified and dated six regional unconformities in the wells and we can recognize several others on the seismic data. The older unconformities (Cretaceous) are related to the tectonics of rifting and seafloor spreading, and may delineate the onset of different stages of the rift process. In the Paleocene-Early Eocene, unconformity development was influenced by episodic volcanism due to the passage of the proto-Iceland hotspot to the north and to a major change in spreading direction in the Labrador Sea. Many of these unconformities are also identified in offshore southwest Greenland and the Grand Banks, suggesting widespread controlling mechanisms. During the post-seafloor spreading stage the effects of mass wasting and slumping, and of paleoenvironmental controls on the stratigraphy, were more pronounced. We discuss the petroleum potential of the Hopedale Basin in terms of the structures we see on the seismic data, and highlight the Bjarni Formation, which likely contains the most prospective source and reservoir rocks in this Basin.

► A new stratigraphic column is presented for the Labrador shelf geologic section.
► We link older unconformities to the tectonic evolution of the non-volcanic margin.
► Younger unconformities reflect major global sea-level and oceanographic changes.
► We find similar patterns on the west Greenland margin and the Jeanne d’Arc basin.
► Large margin offsets may be associated with gas-bearing inversion structures.